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Sample records for control coating performance

  1. Review of End-of-Life Thermal Control Coating Performance

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Kline, Sara E.

    2008-01-01

    White thermal control coatings capable of long term performance are needed for Fission Surface Power (FSP) where heat from a nuclear reactor placed on the surface of the Moon must be rejected to the environment. The threats to thermal control coating durability on the lunar surface are electrons, protons, and ultraviolet radiation. The anticipated damage to the coating is a gradual darkening over time. The increase in solar absorptance would, in essence, add a cyclic heat load to the radiator. The greater the darkening, the greater the added heat load. The cyclic heat load could ultimately impart a cyclic influence on FSP system performance. No significant change in emittance is anticipated. Optical properties degradation data were found in the open literature for the Z-93 series of thermal control paints. Additional optical properties degradation data were found from the Lunar Orbiter V mission, the Optical Properties Monitor, and the Materials International Space Station Experiment. Anticipated end-of-life thermal control coating performance for a FSP installation is postulated. With the FSP installation located away from landing and launching areas, and out of line-of-sight, lunar dust from human activity may not be a threat. The benefits of investing in next generation thermal control paint chemistry are explored.

  2. NEW HIGHER PERFORMANCE LOW COST SELECTIVE SOLAR RADIATION CONTROL COATINGS

    SciTech Connect

    Timothy Ellison; Buddie Dotter; David Tsu

    2003-10-28

    Energy Conversion Devices, Inc., ECD, has developed a new high-speed low-cost process for depositing high quality dielectric optical coatings--Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD). This process can deposit SiO{sub x} about 10 times faster than the state-of-the-art conventional technology, magnetron sputtering, at about 1/10th the cost. This process is also being optimized for depositing higher refractive index materials such as Si{sub 3}N{sub 4} and TiO{sub 2}. In this program ECD, in collaboration with Southwall Technologies, Inc. (STI), demonstrated that this process can be used to fabricate high performance low cost Selective Solar Radiation Control (SSRC) films for use in the automotive industry. These coatings were produced on thin (2 mil thick) PET substrates in ECD's pilot roll-to-roll pilot MPECVD deposition machine. Such film can be laminated with PVB in a vehicle's windows. This process can also be used to deposit the films directly onto the glass. Such highly selective films, with a visible transmission (T{sub vis}) of > 70% and a shading coefficient of < 60% can significantly reduce the heat entering a car from solar radiation. Consequently, passenger comfort is increased and the energy needed to operate air conditioning (a/c) systems is reduced; consequently smaller a/c systems can be employed resulting in improved vehicle fuel efficiency.

  3. Fabrication of color-controllable superhydrophobic copper compound coating with decoration performance

    NASA Astrophysics Data System (ADS)

    Tan, Cui; Li, Qing; Cai, Peng; Yang, Na; Xi, Zhongxian

    2015-02-01

    A facile and low-cost method for fabricating the color-controllable superhydrophobic coatings on copper was reported in this paper. By simply changing the electrolytic conditions, tunable color surfaces can be obtained. The fundamental cause of color variation should be attributed to the composition of resulting coatings. After modification with stearic acid, the contact angles (CA) of samples with three different colors are 156.8°, 160.0°, 162.8°, respectively, and slide angles (SA) are all nearly 1°. In addition, potentiodynamic polarization test, pH stability, atmospheric exposure test, antibacterial test, abrasion test and tape adhesion test were also performed from the viewpoint of the physical stability and chemical stability of superhydrophobic surfaces. Results indicate that the obtained surfaces be of excellent environmental adaptability, high anti-corrosion ability, and good mechanical property. Results reported here would be helpful for enlarging the application of superhydrophobic surface. Moreover, this method, chemical in situ growth of colored coating, is a new strategy for preparing color-tuned superhydrophobic surface and could be applied on other metal substrates.

  4. Optical Coating Performance and Thermal Structure Design for Heat Reflectors of JWST Electronic Control Unit

    NASA Technical Reports Server (NTRS)

    Quijada, Manuel A.; Threat, Felix; Garrison, Matt; Perrygo, Chuck; Bousquet, Robert; Rashford, Robert

    2008-01-01

    The James Webb Space Telescope (JWST) consists of an infrared-optimized Optical Telescope Element (OTE) that is cooled down to 40 degrees Kelvin. A second adjacent component to the OTE is the Integrated Science Instrument Module, or ISIM. This module includes the electronic compartment, which provides the mounting surfaces and ambient thermally controlled environment for the instrument control electronics. Dissipating the 200 watts generated from the ISIM structure away from the OTE is of paramount importance so that the spacecraft's own heat does not interfere with the infrared light detected from distant cosmic sources. This technical challenge is overcome by a thermal subsystem unit that provides passive cooling to the ISIM control electronics. The proposed design of this thermal radiator consists of a lightweight structure made out of composite materials and low-emittance metal coatings. In this paper, we will present characterizations of the coating emittance, bidirectional reflectance, and mechanical structure design that will affect the performance of this passive cooling system.

  5. The performance of thermal control coatings on LDEF and implications to future spacecraft

    NASA Technical Reports Server (NTRS)

    Wilkes, Donald R.; Miller, Edgar R.; Mell, Richard J.; Lemaster, Paul S.; Zwiener, James M.

    1993-01-01

    The stability of thermal control coatings over the lifetime of a satellite or space platform is crucial to the success of the mission. With the increasing size, complexity, and duration of future missions, the stability of these materials becomes even more important. The Long Duration Exposure Facility (LDEF) offered an excellent testbed to study the stability and interaction of thermal control coatings in the low-Earth orbit (LEO) space environment. Several experiments on LDEF exposed thermal control coatings to the space environment. This paper provides an overview of the different materials flown and their stability during the extended LDEF mission. The exposure conditions, exposure environment, and measurements of materials properties (both in-space and postflight) are described. The relevance of the results and the implications to the design and operation of future space vehicles are also discussed.

  6. Correlation between Hierarchical Structure and Processing Control of Large-area Spray-coated Polymer Solar Cells toward High Performance

    NASA Astrophysics Data System (ADS)

    Huang, Yu-Ching; Tsao, Cheng-Si; Cha, Hou-Chin; Chuang, Chih-Min; Su, Chun-Jen; Jeng, U.-Ser; Chen, Charn-Ying

    2016-01-01

    The formation mechanism of a spray-coated film is different from that of a spin-coated film. This study employs grazing incidence small- and wide-angle X-ray Scattering (GISAXS and GIWAXS, respectively) quantitatively and systematically to investigate the hierarchical structure and phase-separated behavior of a spray-deposited blend film. The formation of PCBM clusters involves mutual interactions with both the P3HT crystal domains and droplet boundary. The processing control and the formed hierarchical structure of the active layer in the spray-coated polymer/fullerene blend film are compared to those in the spin-coated film. How the different post-treatments, such as thermal and solvent vapor annealing, tailor the hierarchical structure of the spray-coated films is quantitatively studied. Finally, the relationship between the processing control and tailored BHJ structures and the performance of polymer solar cell devices is established here, taking into account the evolution of the device area from 1 × 0.3 and 1 × 1 cm2. The formation and control of the special networks formed by the PCBM cluster and P3HT crystallites, respectively, are related to the droplet boundary. These structures are favorable for the transverse transport of electrons and holes.

  7. Correlation between Hierarchical Structure and Processing Control of Large-area Spray-coated Polymer Solar Cells toward High Performance

    PubMed Central

    Huang, Yu-Ching; Tsao, Cheng-Si; Cha, Hou-Chin; Chuang, Chih-Min; Su, Chun-Jen; Jeng, U-Ser; Chen, Charn-Ying

    2016-01-01

    The formation mechanism of a spray-coated film is different from that of a spin-coated film. This study employs grazing incidence small- and wide-angle X-ray Scattering (GISAXS and GIWAXS, respectively) quantitatively and systematically to investigate the hierarchical structure and phase-separated behavior of a spray-deposited blend film. The formation of PCBM clusters involves mutual interactions with both the P3HT crystal domains and droplet boundary. The processing control and the formed hierarchical structure of the active layer in the spray-coated polymer/fullerene blend film are compared to those in the spin-coated film. How the different post-treatments, such as thermal and solvent vapor annealing, tailor the hierarchical structure of the spray-coated films is quantitatively studied. Finally, the relationship between the processing control and tailored BHJ structures and the performance of polymer solar cell devices is established here, taking into account the evolution of the device area from 1 × 0.3 and 1 × 1 cm2. The formation and control of the special networks formed by the PCBM cluster and P3HT crystallites, respectively, are related to the droplet boundary. These structures are favorable for the transverse transport of electrons and holes. PMID:26817585

  8. Effects of high energy simulated space radiation on polymeric second-surface mirrors. [thermal control coatings - performance tests

    NASA Technical Reports Server (NTRS)

    Eogdall, L. B.; Cannaday, S. S.

    1975-01-01

    A radiation effects experimental program was performed, in which second surface mirror type thermal control coatings were exposed to ultraviolet radiation, electrons, and protons simultaneously. Stability was assessed by making periodic spectral reflectance measurements in situ (and in air after testing for comparison). Solar absorption coefficients were derived by computer. Many of the exposed materials showed large amounts of degradation in reflectance absorptance, principally due to the electron exposure. A series of tests was conducted, leading to the identification of a modified second surface mirror that shows considerable improvement and promise for stability during thermal control applications in a charged particle space radiation environment.

  9. Enhanced performance and functionality of titanium dioxide papermaking pigments with controlled morphology and surface coating

    NASA Astrophysics Data System (ADS)

    Nelson, Kimberly L.

    Novel, tailored titanium dioxide pigments with controllable nanoscale morphological features were shown to significantly enhance the optical and strength properties of paper. The opacifying power of synthesized polycrystalline TiO2 particles in a cellulose matrix was found experimentally to be superior to that of a commercial rutile pigment, depending on the crystal structure of the synthesized particles. High aspect ratio polycrystalline rutile pigments composed of a linear linkage of several individual rutile crystals gave 6% more opacity than the commercial rutile pigment. Theoretical light scattering calculations using the T-Matrix Method showed the light scattering efficiency of linearly arranged polycrystalline rutile particles to depend on number and size of crystals composing the particle and confirmed the higher efficiency of the synthesized polycrystalline rutile pigments over commercial rutile. The opacifying power of hollow polycrystalline rutile particles was found experimentally to be superior to that of a commercial rutile pigment in a highly pressed bleached fiber matrix, depending on cavity size, while the opacifying power of silica-rutile titania core-shell particles was found comparable to commercial rutile at constant titania loading. The light scattering efficiency of titania core-shell particles was also shown to be dependant on the light scattering efficiency of the core material. The overall particle shape and aspect ratio of titania core-shell and hollow nanoparticles were shown to be tunable by choosing an appropriate template and coating thickness in layer-by-layer or sol-gel templating synthesis. Inorganic-cellulose core-shell and hollow cellulose nanoparticles were prepared by self-encapsulation with regenerated cellulose via precipitation of cellulose in a polyacrylic acid hydrogel layer surrounding inorganic particle templates in 4-Methylmorpholine N-oxide (NMMO) monohydrate solution. This discrete encapsulation of inorganic pigments

  10. UNDERWATER COATINGS FOR CONTAMINATION CONTROL

    SciTech Connect

    Julia L. Tripp; Kip Archibald; Ann Marie Phillips; Joseph Campbell

    2004-02-01

    The Idaho National Laboratory (INL) deactivated several aging nuclear fuel storage basins. Planners for this effort were greatly concerned that radioactive contamination present on the basin walls could become airborne as the sides of the basins became exposed during deactivation and allowed to dry after water removal. One way to control this airborne contamination was to fix the contamination in place while the pool walls were still submerged. There are many underwater coatings available on the market for marine, naval and other applications. A series of tests were run to determine whether the candidate underwater fixatives were easily applied and adhered well to the substrates (pool wall materials) found in INL fuel pools. Lab-scale experiments were conducted by applying fourteen different commercial underwater coatings to four substrate materials representative of the storage basin construction materials, and evaluating their performance. The coupons included bare concrete, epoxy painted concrete, epoxy painted carbon steel, and stainless steel. The evaluation criteria included ease of application, adherence to the four surfaces of interest, no change on water clarity or chemistry, non-hazardous in final applied form and be proven in underwater applications. A proprietary two-part, underwater epoxy owned by S. G. Pinney and Associates was selected from the underwater coatings tested for application to all four pools. Divers scrubbed loose contamination off the basin walls and floors using a ship hull scrubber and vacuumed up the sludge. The divers then applied the coating using a special powered roller with two separate heated hoses that allowed the epoxy to mix at the roller surface was used to eliminate pot time concerns. The walls were successfully coated and water was removed from the pools with no detectable airborne contamination releases.

  11. High Temperature Oxidation Performance of Aluminide Coatings

    SciTech Connect

    Pint, Bruce A; Zhang, Ying; Haynes, James A; Wright, Ian G

    2004-01-01

    Aluminide coatings are of interest for many high temperature applications because of the possibility of improving the oxidation resistance of structural alloys by forming a protective external alumina scale. Steam and exhaust gas environments are of particular interest because alumina is less susceptible to the accelerated attack due to hydroxide formation observed for chromia- and silica-forming alloys and ceramics. For water vapor testing, one ferritic (Fe-9Cr-1Mo) and one austenitic alloy (304L) have been selected as substrate materials and CVD coatings have been used in order to have a well-controlled, high purity coating. It is anticipated that similar aluminide coatings could be made by a higher-volume, commercial process such as pack cementation. Previous work on this program has examined as-deposited coatings made by high and low Al activity CVD processes and the short-term performance of these coatings. The current work is focusing on the long term behavior in both diffusion tests16 and oxidation tests of the thicker, high Al activity coatings. For long-term coating durability, one area of concern has been the coefficient of thermal expansion (CTE) mismatch between coating and substrate. This difference could cause cracking or deformation that could reduce coating life. Corrosion testing using thermal cycling is of particular interest because of this potential problem and results are presented where a short exposure cycle (1h) severely degraded aluminide coatings on both types of substrates. To further study the potential role of aluminide coatings in fossil energy applications, several high creep strength Ni-base alloys were coated by CVD for testing in a high pressure (20atm) steam-CO{sub 2} environment for the ZEST (zero-emission steam turbine) program. Such alloys would be needed as structural and turbine materials in this concept. For Ni-base alloys, CVD produces a {approx}50{mu}m {beta}-NiAl outer layer with an underlying interdiffusion zone

  12. Multilayer coatings for solar energy control applications

    SciTech Connect

    Kivaisi, R.T.; Mbise, G.

    1993-12-31

    This work presents some results for window coatings that are suitable for solar control applications. Selected research results are given for metal/dielectric based coatings optimized for normal incidence. These coatings can be used to improve the performance of windows both for architectural and automobile sectors. Surface coatings which are transparent at 0.3 < {lambda} < 0.7 {micro}m can be used to solar control windows. A thin homogeneous noble metal film (eg Ag) can combine short wavelength transmittance with high long wavelength reflectance. By embedding the metal film between high refractive index dielectric layers one can optimize the transmittance in the desired spectral region. Transmittance data for multilayer stacks designed for normal and non normal incidence to the coating are presented.

  13. Spacecraft Thermal Control Coatings References

    NASA Technical Reports Server (NTRS)

    Kauder, Lonny

    2005-01-01

    The successful thermal design of spacecraft depends in part on a knowledge of the solar absorption and hemispherical emittance of the thermal control coatings used in and on the spacecraft. Goddard Space Flight Center has had since its beginning a group whose mission has been to provide thermal/optical properties data of thermal control coatings to thermal engineers. This handbook represents a summary of the data and knowledge accumulated over many years at GSFC.

  14. Coating Microstructure-Property-Performance Issues

    SciTech Connect

    Terry C. Totemeier; Richard N. Wright

    2005-05-01

    Results of studies on the relationships between spray parameters and performance of thermally-sprayed intermetallic coatings for high-temperature oxidation and corrosion resistance are presented. Coating performance is being assessed by corrosion testing of free-standing coatings, thermal cycling of coating substrates, and coating ductility measurement. Coating corrosion resistance was measured in a simulated coal combustion gas environment (N2-CO-CO2-H2O-H2S) at temperatures from 500 to 800°C using thermo-gravimetric analysis (TGA). TGA testing was also performed on a typical ferritic-martensitic steel, austenitic stainless steel, and a wrought Fe3Al-based alloy for direct comparison to coating behavior. FeAl and Fe3Al coatings showed corrosion rates slightly greater than that of wrought Fe3Al, but markedly lower than the steels at all temperatures. The corrosion rates of the coatings were relatively independent of temperature. Thermal cycling was performed on coated 316SS and nickel alloy 600 substrates from room temperature to 800°C to assess the relative effects of coating microstructure, residual stress, and thermal expansion mismatch on coating cracking by thermal fatigue. Measurement of coating ductility was made by acoustic emission monitoring of coated 316SS tensile specimens during loading.

  15. Weathering of Thermal Control Coatings

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Tuan, George C.; Westheimer, David T.; Peters, Wanda C.; Kauder, Lonny R.; Triolo, Jack J.

    2007-01-01

    Spacecraft radiators reject heat to their surroundings. Radiators can be deployable or mounted on the body of the spacecraft. NASA's Crew Exploration Vehicle is to use body mounted radiators. Coatings play an important role in heat rejection. The coatings provide the radiator surface with the desired optical properties of low solar absorptance and high infrared emittance. These specialized surfaces are applied to the radiator panel in a number of ways, including conventional spraying, plasma spraying, or as an applique. Not specifically designed for a weathering environment, little is known about the durability of conventional paints, coatings, and appliques upon exposure to weathering and subsequent exposure to solar wind and ultraviolet radiation exposure. In addition to maintaining their desired optical properties, the coatings must also continue to adhere to the underlying radiator panel. This is a challenge, as new composite radiator panels are being considered as replacements for the aluminum panels used previously. Various thermal control paints, coatings, and appliques were applied to aluminum and isocyanate ester composite coupons and were exposed for 30 days at the Atmospheric Exposure Site of the Kennedy Space Center s Beach Corrosion Facility for the purpose of identifying their durability to weathering. Selected coupons were subsequently exposed to simulated solar wind and vacuum ultraviolet radiation to identify the effect of a simulated space environment on the as-weathered surfaces. Optical properties and adhesion testing were used to document the durability of the paints and coatings. The purpose of this paper is to present the results of the weathering testing and to summarize the durability of several thermal control paints, coatings, and appliques to weathering and postweathering environments.

  16. High performance Cu adhesion coating

    SciTech Connect

    Lee, K.W.; Viehbeck, A.; Chen, W.R.; Ree, M.

    1996-12-31

    Poly(arylene ether benzimidazole) (PAEBI) is a high performance thermoplastic polymer with imidazole functional groups forming the polymer backbone structure. It is proposed that upon coating PAEBI onto a copper surface the imidazole groups of PAEBI form a bond with or chelate to the copper surface resulting in strong adhesion between the copper and polymer. Adhesion of PAEBI to other polymers such as poly(biphenyl dianhydride-p-phenylene diamine) (BPDA-PDA) polyimide is also quite good and stable. The resulting locus of failure as studied by XPS and IR indicates that PAEBI gives strong cohesive adhesion to copper. Due to its good adhesion and mechanical properties, PAEBI can be used in fabricating thin film semiconductor packages such as multichip module dielectric (MCM-D) structures. In these applications, a thin PAEBI coating is applied directly to a wiring layer for enhancing adhesion to both the copper wiring and the polymer dielectric surface. In addition, a thin layer of PAEBI can also function as a protection layer for the copper wiring, eliminating the need for Cr or Ni barrier metallurgies and thus significantly reducing the number of process steps.

  17. Effect of W coating on microengine performance

    SciTech Connect

    MANI,SEETHAMBAL S.; FLEMING,JAMES G.; WALRAVEN,JEREMY A.; SNIEGOWSKI,JEFFRY J.; DE BOER,MAARTEN P.; IRWIN,LLOYD W.; TANNER,DANELLE M.; LAVAN,DAVID A.; DUGGER,MICHAEL T.; JAKUBCZAK II,JEROME F.; MILLER,WILLIAM M.

    2000-03-01

    Two major problems associated with Si-based MEMS (MicroElectroMechanical Systems) devices are stiction and wear. Surface modifications are needed to reduce both adhesion and friction in micromechanical structures to solve these problems. In this paper, the authors present a CVD (Chemical Vapor Deposition) process that selectively coats MEMS devices with tungsten and significantly enhances device durability. Tungsten CVD is used in the integrated-circuit industry, which makes this approach manufacturable. This selective deposition process results in a very conformal coating and can potentially address both stiction and wear problems confronting MEMS processing. The selective deposition of tungsten is accomplished through the silicon reduction of WF{sub 6}. The self-limiting nature of the process ensures consistent process control. The tungsten is deposited after the removal of the sacrificial oxides to minimize stress and process integration problems. The tungsten coating adheres well and is hard and conducting, which enhances performance for numerous devices. Furthermore, since the deposited tungsten infiltrates under adhered silicon parts and the volume of W deposited is less than the amount of Si consumed, it appears to be possible to release adhered parts that are contacted over small areas such as dimples. The wear resistance of tungsten coated parts has been shown to be significantly improved by microengine test structures.

  18. Lithium coatings on NSTX plasma facing components and its effects on boundary control, core plasma performance, and operation

    SciTech Connect

    Kugel, H. W.; Bell, M. G.; Maingi, R.

    2010-01-01

    NSTX high power divertor plasma experiments have used in succession lithium pellet injection (LPI), evaporated lithium, and injected lithium powder to apply lithium coatings to graphite plasma facing components. In 2005, following the wall conditioning and LPI, discharges exhibited edge density reduction and performance improvements. Since 2006, first one, and now two lithium evaporators have been used routinely to evaporate lithium onto the lower divertor region at total rates of 10-70 mg/min for periods 5-10 min between discharges. Prior to each discharge, the evaporators are withdrawn behind shutters. Significant improvements in the performance of NBI heated divertor discharges resulting from these lithium depositions were observed. These evaporators are now used for more than 80% of NSTX discharges. Initial work with injecting fine lithium powder into the edge of NBI heated deuterium discharges yielded comparable changes in performance. Several operational issues encountered with lithium wall conditions, and the special procedures needed for vessel entry are discussed. The next step in this work is installation of a liquid lithium divertor surface on the outer part of the lower divertor.

  19. Lithium Coatings on NSTX Plasma Facing Components and Its Effects On Boundary Control, Core Plasma Performance, and Operation

    SciTech Connect

    H.W.Kugel, M.G.Bell, H.Schneider, J.P.Allain, R.E.Bell, R Kaita, J.Kallman, S. Kaye, B.P. LeBlanc, D. Mansfield, R.E. Nygen, R. Maingi, J. Menard, D. Mueller, M. Ono, S. Paul, S.Gerhardt, R.Raman, S.Sabbagh, C.H.Skinner, V.Soukhanovskii, J.Timberlake, L.E.Zakharov, and the NSTX Research Team

    2010-01-25

    NSTX high-power divertor plasma experiments have used in succession lithium pellet injection (LPI), evaporated lithium, and injected lithium powder to apply lithium coatings to graphite plasma facing components. In 2005, following wall conditioning and LPI, discharges exhibited edge density reduction and performance improvements. Since 2006, first one, and now two lithium evaporators have been used routinely to evaporate lithium onto the lower divertor region at total rates of 10-70 mg/min for periods 5-10 min between discharges. Prior to each discharge, the evaporators are withdrawn behind shutters. Significant improvements in the performance of NBI heated divertor discharges resulting from these lithium depositions were observed. These evaporators are now used for more than 80% of NSTX discharges. Initial work with injecting fine lithium powder into the edge of NBI heated deuterium discharges yielded comparable changes in performance. Several operational issues encountered with lithium wall conditions, and the special procedures needed for vessel entry are discussed. The next step in this work is installation of a Liquid Lithium Divertor surface on the outer part of the lower divertor.

  20. Gear Performance Improved by Coating

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.

    2004-01-01

    Gears, bearings, and other mechanical elements transmit loads through contacting surfaces. Even if properly designed, manufactured, installed, and maintained, gears and bearings will eventually fail because of the fatigue of the working surfaces. Economical means for extending the fatigue lives of gears and bearings are highly desired, and coatings offer the opportunity to engineer surfaces to extend the fatigue lives of mechanical components. A tungsten-containing diamondlike-carbon coating exhibiting high hardness, low friction, and good toughness was evaluated for application to spur gears. Fatigue testing was done at the NASA Glenn Research Center on both uncoated and coated spur gears. The results showed that the coating extended the surface fatigue lives of the gears by a factor of about 5 relative to the uncoated gears. For the experiments, a lot of spur test gears made from AISI 9310 gear steel were case-carburized and ground to aerospace specifications. The geometries of the 28-tooth, 8-pitch gears were verified as meeting American Gear Manufacturing Association (AGMA) quality class 12. One-half of the gears were randomly selected for coating. The method of coating was selected to achieve desired adherence, toughness, hardness, and low-friction characteristics. First the gears to be coated were prepared by blasting (vapor honing) with Al2O3 particles and cleaning. Then, the gears were provided with a thin adhesion layer of elemental chromium followed by magnetron sputtering of the outer coating consisting of carbon (70 at.%), hydrogen (15 at.%), tungsten (12 at.%), and nickel (3 at.%) (atomic percent at the surface). In total, the coating thickness was about 2.5 to 3 microns. As compared with the steel substrate, the coated surface was harder by a factor of about 2 and had a smaller elastic modulus. All gears were tested using a 5-centistoke synthetic oil, a 10,000-rpm rotation speed, and a hertzian contact stress of at least 1.7 GPa (250 ksi). Tests were

  1. Instrumental color control for metallic coatings

    NASA Astrophysics Data System (ADS)

    Chou, W.; Han, Bing; Cui, Guihua; Rigg, Bryan; Luo, Ming R.

    2002-06-01

    This paper describes work investigating a suitable color quality control method for metallic coatings. A set of psychological experiments was carried out based upon 50 pairs of samples. The results were used to test the performance of various color difference formulae. Different techniques were developed by optimising the weights and/or the lightness parametric factors of colour differences calculated from the four measuring angles. The results show that the new techniques give a significant improvement compared to conventional techniques.

  2. High-Performance Polyimide Powder Coatings

    NASA Technical Reports Server (NTRS)

    Leahy, Jonathan J.

    2014-01-01

    Researchers at NASA's Kennedy Space Center have developed advanced powder coatings for longer-lasting, improved corrosion control. The results of preliminary tests of the coatings and their resistance to salt spray corrosion are very encouraging, and commercial partners are sought for further development.

  3. Wear Performance of Laser Processed Tantalum Coatings

    PubMed Central

    Dittrick, Stanley; Balla, Vamsi Krishna; Bose, Susmita; Bandyopadhyay, Amit

    2011-01-01

    This first generation investigation evaluates the in vitro tribological performance of laser-processed Ta coatings on Ti for load-bearing implant applications. Linear reciprocating wear tests in simulated body fluid showed one order of magnitude less wear rate, of the order of 10−4mm3(N.m)−1, for Ta coatings compared to Ti. Our results demonstrate that Ta coatings can potentially minimize the early-stage bone-implant interface micro-motion induced wear debris generation due to their excellent bioactivity comparable to that of hydroxyapatite (HA), high wear resistance and toughness compared to popular HA coatings. PMID:22058608

  4. Incorporation of capsaicin in silicone coatings for enhanced antifouling performance

    NASA Astrophysics Data System (ADS)

    Reddy Jaggari, Karunakar; Zhang Newby, Bi-Min

    2002-03-01

    Successful use of capsaicin as insect and animal repellant propelled us to use it as a possible antifouling agent. Its non-toxic, non-biocidal, non-leaching properties make it a viable alternative to organotin compounds. In order to optimize the anti-fouling performance of the coating, silicone, the most effective foul-release marine coating, was chosen as the carrier. We have incorporated capsaicin into silicone coating, by both bulk entrapment and surface immobilization. Contact angle measurements on capsaicin-incorporated silicone exhibited an increase in wettability, owing to the presence of capsaicin. FTIR study further confirmed the incorporation of capsaicin in silicone. Bacterial attachment studies were conducted using lake Erie water. While bacteria liberally inhabited the control coating, their presence on the capsaicin-incorporated coating was found to be minimal. These preliminary studies indicate that capsaicin incorporated silicone could be a viable environment friendly alternative to currently used antifouling coatings.

  5. Controlled release drug coatings on flexible neural probes.

    PubMed

    Mercanzini, Andre; Reddy, Sai; Velluto, Diana; Colin, Philippe; Maillard, Anne; Bensadoun, Jean-Charles; Bertsch, Arnaud; Hubbell, Jeffrey A; Renaud, Philippe

    2007-01-01

    We present the development, characterization and in vivo validation of a novel drug eluting coating that has been applied to flexible neural probes. The coating consists of drug eluting nanoparticles loaded with an anti-inflammatory drug embedded in a biodegradable polymer. The drug eluting coating is applied to flexible polymer neural probes with platinum electrodes. The drug eluting device is implanted in one hemisphere of a rat, while a control device is implanted in the opposite hemisphere. Impedance measurements are performed to determine the effect of the drug eluting coating on the tissue reaction surrounding the probe and the electrical characteristics of the devices. Probes that are coated with drug eluting coatings show better long term impedance characteristics over control probes. These coatings can be used to increase the reliability and long term success of neural prostheses. PMID:18003541

  6. Simulation to coating weight control for galvanizing

    NASA Astrophysics Data System (ADS)

    Wang, Junsheng; Yan, Zhang; Wu, Kunkui; Song, Lei

    2013-05-01

    Zinc coating weight control is one of the most critical issues for continuous galvanizing line. The process has the characteristic of variable-time large time delay, nonlinear, multivariable. It can result in seriously coating weight error and non-uniform coating. We develop a control system, which can automatically control the air knives pressure and its position to give a constant and uniform zinc coating, in accordance with customer-order specification through an auto-adaptive empirical model-based feed forward adaptive controller, and two model-free adaptive feedback controllers . The proposed models with controller were applied to continuous galvanizing line (CGL) at Angang Steel Works. By the production results, the precise and stability of the control model reduces over-coating weight and improves coating uniform. The product for this hot dip galvanizing line does not only satisfy the customers' quality requirement but also save the zinc consumption.

  7. A Multifunctional Coating for Autonomous Corrosion Control

    NASA Technical Reports Server (NTRS)

    Calle, Luz M.; Li, Wenyan; Buhrow, Jerry W.; Jolley, Scott t.

    2011-01-01

    Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it. The multi-functionality of the coating is based on microencapsulation technology specifically designed for corrosion control applications. This design has, in addition to all the advantages of existing microcapsulation designs, the corrosion controlled release function that triggers the delivery of corrosion indicators and inhibitors on demand, only when and where needed. Microencapsulation of self-healing agents for autonomous repair of mechanical damage to the coating is also being pursued. Corrosion indicators, corrosion inhibitors, as well as self-healing agents, have been encapsulated and dispersed into several paint systems to test the corrosion detection, inhibition, and self-healing properties of the coating. Key words: Corrosion, coating, autonomous corrosion control, corrosion indication, corrosion inhibition, self-healing coating, smart coating, multifunctional coating, microencapsulation.

  8. Analysis of Thermal Control Coatings on MISSE for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Finckenor, Miria; Kenny, Mike

    2007-01-01

    Many different passive thermal control materials were flown as part of the Materials on International Space Station Experiment. Engineers and scientists at the Marshall Space Flight Center have analyzed a number of these materials, including: Zinc oxide/potassium silicate coating, Zinc oxide/potassium silicate/silicone coating, Zinc orthotitanate/potassium silicate coating, Electrically conductive thermal control coatings and Various coatings for part marking, automated rendezvous and capture, and astronaut visual aids These and other material samples were exposed to the low Earth orbital environment of atormc oxygen, ultraviolet radiation, thermal cycling, and hard vacuum, though atomic oxygen exposure was very limited for some samples. Solar absorptance, infrared emittance, and mass measurements indicate the durability of these materials to withstand the space environment. The effect of contamination from an active space station on the performance of white thermal control coatings is discussed.

  9. Underwater Coatings for Contamination Control

    SciTech Connect

    Julia L. Tripp; Kip Archibald; Ann-Marie Phillips; Joseph Campbell

    2004-02-01

    The Idaho National Engineering and Environmental Laboratory (INEEL) is deactivating several fuel storage basins. Airborne contamination is a concern when the sides of the basins are exposed and allowed to dry during water removal. One way of controlling this airborne contamination is to fix the contamination in place while the pool walls are still submerged. There are many underwater coatings available on the market that are used in marine, naval and other applications. A series of tests were run to determine whether the candidate underwater fixatives are easily applied and adhere well to the substrates (pool wall materials) found in INEEL fuel pools. The four pools considered included 1) Test Area North (TAN-607) with epoxy painted concrete walls; 2) Idaho Nuclear Technology and Engineering Center (INTEC) (CPP-603) with bare concrete walls; 3) Materials Test Reactor (MTR) Canal with stainless steel lined concrete walls; and 4) Power Burst Facility (PBF-620) with stainless steel lined concrete walls on the bottom and epoxy painted carbon steel lined walls on the upper portions. Therefore, the four materials chosen for testing included bare concrete, epoxy painted concrete, epoxy painted carbon steel, and stainless steel. The typical water temperature of the pools varies from 55oF to 80oF dependent on the pool and the season. These tests were done at room temperature. The following criteria were used during this evaluation. The underwater coating must: · Be easy to apply · Adhere well to the four surfaces of interest · Not change or have a negative impact on water chemistry or clarity · Not be hazardous in final applied form · Be proven in other underwater applications. In addition, it is desirable for the coating to have a high pigment or high cross-link density to prevent radiation from penetrating. This paper will detail the testing completed and the test results. A proprietary two-part, underwater epoxy owned by S. G. Pinney and Associates was selected to

  10. Variable anodic thermal control coating

    NASA Technical Reports Server (NTRS)

    Gilliland, C. S.; Duckett, J. (Inventor)

    1983-01-01

    A process for providing a thermal control solar stable surface coating for aluminum surfaces adapted to be exposed to solar radiation wherein selected values within the range of 0.10 to 0.72 thermal emittance (epsilon sub tau) and 0.2 to 0.4 solar absorptance (alpha subs) are reproducibly obtained by anodizing the surface area in a chromic acid solution for a selected period of time. The rate voltage and time, along with the parameters of initial epsilon sub tau and alpha subs, temperature of the chromic acid solution, acid concentration of the solution and the material anodized determines the final values of epsilon/tau sub and alpha sub S. 9 Claims, 5 Drawing Figures.

  11. Robotic weld overlay coatings for erosion control

    NASA Astrophysics Data System (ADS)

    Levin, B. F.; Dupont, J. N.; Marder, A. R.

    1994-01-01

    Research is being conducted to develop criteria for selecting weld overlay coatings for erosion mitigation in circulated fluidized beds. Twelve weld overlay alloys were deposited on 1018 steel substrates using plasma arc welding. Ten samples from each coating were prepared for erosion testing. All selected coatings were erosion tested at 400C and their erosion resistance and microstructure evaluated. Steady state erosion rates were similar for several weld overlay coatings (Ultimet, Inconel-625, Iron-Aluminide, 316L SS, and High Chromium Cast Iron) and were considerably lower than the remaining coating evaluated. These coatings had different base (Co, Fe, Ni-base). No correlations were found between room temperature microhardness of the weld overlay coatings and their erosion resistance at elevated temperature, although this criteria is often thought to be an indicator of erosion resistance. It was suggested that the coatings that showed similar erosion rates may have similar mechanical properties such as fracture strength, toughness and work hardening rates at this temperature. During the past quarter, Iron-Aluminide, Inconel-625, and 316L SS coatings were selected for more detailed investigations based upon the preliminary erosion test results. Microhardness tests were performed on eroded samples to determine the size of the work hardened zone and change in coatings hardness due to erosion. The work hardened zone was correlated with erosion resistance of the coatings. Additional Iron-Aluminide, Inconel-625, and 316L SS coatings were deposited on 1018 steel substrates.

  12. Space stable thermal control coatings

    NASA Technical Reports Server (NTRS)

    Harada, Y.

    1982-01-01

    A specification quality zinc orthotitanate coating was developed. This silicate-bonded Zn2TiO4 coating is discussed. The effects of precursor chemistry, precursor mixing procedures, stoichiometry variations, and of different heat treatments on the physical and optical properties of Zn2TiO4 are investigated. Inorganic silicates are compared to organic silicone binder systems. The effects of pigment to binder ratio, water content, and of different curing procedures on the optical and physical properties of Zn2TiO4 potassium silicate coatings are also studied. Environmental tests were conducted to determine the UV vacuum stability of coatings for durations up to 5000 equivalent Sun hours.

  13. HIGH-PERFORMANCE COATING MATERIALS

    SciTech Connect

    SUGAMA,T.

    2007-01-01

    Corrosion, erosion, oxidation, and fouling by scale deposits impose critical issues in selecting the metal components used at geothermal power plants operating at brine temperatures up to 300 C. Replacing these components is very costly and time consuming. Currently, components made of titanium alloy and stainless steel commonly are employed for dealing with these problems. However, another major consideration in using these metals is not only that they are considerably more expensive than carbon steel, but also the susceptibility of corrosion-preventing passive oxide layers that develop on their outermost surface sites to reactions with brine-induced scales, such as silicate, silica, and calcite. Such reactions lead to the formation of strong interfacial bonds between the scales and oxide layers, causing the accumulation of multiple layers of scales, and the impairment of the plant component's function and efficacy; furthermore, a substantial amount of time is entailed in removing them. This cleaning operation essential for reusing the components is one of the factors causing the increase in the plant's maintenance costs. If inexpensive carbon steel components could be coated and lined with cost-effective high-hydrothermal temperature stable, anti-corrosion, -oxidation, and -fouling materials, this would improve the power plant's economic factors by engendering a considerable reduction in capital investment, and a decrease in the costs of operations and maintenance through optimized maintenance schedules.

  14. Critical factors of coating performance in Kraft pulping digesters

    SciTech Connect

    Verstak, A.A.; Baranovski, V.E.; Calkins, M.

    1999-07-01

    Not only the coating material corrosion resistance, but also the coating-substrate interface crack resistance and coating permeation to liquor and its vapor are found to be critical factors affecting the coating performance in Kraft pulping digesters. The behavior of electric-arc and HVOF sprayed coatings is discussed.

  15. Laboratory electron exposure of TSS-1 thermal control coating

    NASA Technical Reports Server (NTRS)

    Vaughn, J. A.; Mccollum, M.; Carruth, M. R., Jr.

    1995-01-01

    RM400, a conductive thermal control coating, was developed for use on the exterior shell of the tethered satellite. Testing was performed by the Engineering Physics Division to quantify effects of the space environment on this coating and its conductive and optical properties. Included in this testing was exposure of RM400 to electrons with energies ranging from 0.1 to 1 keV, to simulate electrons accelerated from the ambient space plasma when the tethered satellite is fully deployed. During this testing, the coating was found to luminesce, and a prolonged exposure of the coating to high-energy electrons caused the coating to darken. This report describes the tests done to quantify the degradation of the thermal control properties caused by electron exposure and to measure the luminescence as a function of electron energy and current density to the satellite.

  16. Neutron absorbing coating for nuclear criticality control

    DOEpatents

    Mizia, Ronald E.; Wright, Richard N.; Swank, William D.; Lister, Tedd E.; Pinhero, Patrick J.

    2007-10-23

    A neutron absorbing coating for use on a substrate, and which provides nuclear criticality control is described and which includes a nickel, chromium, molybdenum, and gadolinium alloy having less than about 5% boron, by weight.

  17. Space stable thermal control coatings

    NASA Technical Reports Server (NTRS)

    Harada, Y.

    1977-01-01

    Efforts to develop an engineering paint were concentrated on inorganic silicate-bonded systems as opposed to the silicone coatings. The UV-vacuum stability of potassium silicate-Zn2TiO4 paints were shown to be quite good. Reflectance optimization of these systems is being studied by maximizing thickness and pigment to binder ratio.

  18. Assessment of Thermal Control and Protective Coatings

    NASA Technical Reports Server (NTRS)

    Mell, Richard J.

    2000-01-01

    This final report is concerned with the tasks performed during the contract period which included spacecraft coating development, testing, and applications. Five marker coatings consisting of a bright yellow handrail coating, protective overcoat for ceramic coatings, and specialized primers for composites (or polymer) surfaces were developed and commercialized by AZ Technology during this program. Most of the coatings have passed space environmental stability requirements via ground tests and/or flight verification. Marker coatings and protective overcoats were successfully flown on the Passive Optical Sample Assembly (POSA) and the Optical Properties Monitor (OPM) experiments flown on the Russian space station MIR. To date, most of the coatings developed and/or modified during this program have been utilized on the International Space Station and other spacecraft. For ISS, AZ Technology manufactured the 'UNITY' emblem now being flown on the NASA UNITY node (Node 1) that is docked to the Russian Zarya (FGB) utilizing the colored marker coatings (white, blue, red) developed by AZ Technology. The UNITY emblem included the US American flag, the Unity logo, and NASA logo on a white background, applied to a Beta cloth substrate.

  19. Porcelain enamel passive thermal control coatings

    NASA Technical Reports Server (NTRS)

    Leggett, H.; King, H. M.

    1978-01-01

    This paper discusses the development and evaluation of a highly adherent, low solar absorptance, porcelain enamel thermal control coating applied to 6061 and 1100 aluminum for space vehicle use. The coating consists of a low index of refraction, transparent host frit and a high volume fraction of titania as rutile, crystallized in-situ, as the scattering medium. Solar absorptance is 0.21 at a coating thickness of 0.013 cm. Hemispherical emittance is 0.88. The change in solar absorptance is 0.03, as measured in-situ, after an exposure of 1000 equivalent sun hours in vacuum.

  20. Control of electroosmosis in coated quartz capillaries

    NASA Technical Reports Server (NTRS)

    Herren, Blair J.; Van Alstine, James; Snyder, Robert S.; Shafer, Steven G.; Harris, J. Milton

    1987-01-01

    The effectiveness of various coatings for controlling the electroosmotic fluid flow that hinders electrophoretic processes is studied using analytical particle microelectrophoresis. The mobilities of 2-micron diameter glass and polystyrene latex spheres (exhibiting both negative and zero effective surface charge) were measured in 2-mm diameter quartz capillaries filled with NaCl solutions within the 3.5-7.8 pH range. It is found that capillary inner surface coatings using 5000 molecular weight (or higher) poly(ethylene glycol): significantly reduced electroosmosis within the selected pH range, were stable for long time periods, and appeared to be more effective than dextran, methylcellulose, or silane coatings.

  1. Space stable thermal control coatings

    NASA Technical Reports Server (NTRS)

    Harada, Y.

    1977-01-01

    Both pigment and paint studies were conducted to determine the effect of calcination conditions on optical properties of Zn2TiO4. Paint studies were concerned with the effects of spraying technique, of pigment to binder ratio, and of thickness on the properties of finished coatings. The results are reviewed in detail. Pigments prepared by calcination at 600 deg. to 800 deg. were evaluated. Low temperature syntheses were conducted to determine; (1) extent of ZnO + TiO2 reaction; and (2) the potential of higher peak reflectance with finer particle size powder obtained at lower temperatures.

  2. A Multifunctional Coating for Autonomous Corrosion Control

    NASA Technical Reports Server (NTRS)

    Calle, Luz M.; Hintze, Paul E.; Li, Wenyan; Buhrow, Jerry W.; Jolley, Scott T.

    2010-01-01

    Corrosion is a destructive process that often causes failure in metallic components and structures. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional, smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to control it. The multi-functionality of the coating is based on microencapsulation technology specifically designed for corrosion control applications. This design has, in addition to all the advantages of other existing microcapsules designs, the corrosion controlled release function that allows the delivery of corrosion indicators and inhibitors on demand only when and where they are needed. Corrosion indicators as well as corrosion inhibitors have been incorporated into the microcapsules, blended into several paint systems, and tested for corrosion detection and protection efficacy.

  3. High-Performance Polyimide Powder Coatings

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Much of the infrastructure at Kennedy Space Center and other NASA sites has been subjected to outside weathering effects for more than 40 years. Because much of this infrastructure has metallic surfaces, considerable effort is continually devoted to developing methods to minimize the effects of corrosion on these surfaces. These efforts are especially intense at KSC, where offshore salt spray and exhaust from Solid Rocket Boosters accelerate corrosion. Coatings of various types have traditionally been the choice for minimizing corrosion, and improved corrosion control methods are constantly being researched. Recent work at KSC on developing an improved method for repairing Kapton (polyimide)-based electrical wire insulation has identified polyimides with much lower melting points than traditional polyimides used for insulation. These lower melting points and the many other outstanding physical properties of polyimides (thermal stability, chemical resistance, and electrical properties) led us to investigate whether they could be used in powder coatings.

  4. Coatings with controlled porosity and chemical properties

    DOEpatents

    Frye, Gregory C.; Brinker, C. Jeffrey; Doughty, Daniel H.; Bein, Thomas; Moller, Karin

    1993-01-01

    Coatings and sensors having both steric and chemical selectivity. Controlled porosity provides the steric selectivity, whereas chemically tailored film properties, using controlled composition or modification by coupling agents, chemical species replacement, or chemical species within pores, provide the chemical selectivity. Single or multiple layers may be provided.

  5. Coatings with controlled porosity and chemical properties

    DOEpatents

    Frye, Gregory C.; Brinker, C. Jeffrey; Doughty, Daniel H.; Bein, Thomas; Moller, Karin

    1996-01-01

    Coatings and sensors having both steric and chemical selectivity. Controlled porosity provides the steric selectivity, whereas chemically tailored film properties, using controlled composition or modification by coupling agents, chemical species replacement, or chemical species within pores, provide the chemical selectivity. Single or multiple layers may be provided.

  6. Coatings with controlled porosity and chemical properties

    DOEpatents

    Frye, G.C.; Brinker, C.J.; Doughty, D.H.; Bein, T.; Moller, K.

    1996-12-31

    Coatings and sensors are disclosed having both steric and chemical selectivity. Controlled porosity provides the steric selectivity, whereas chemically tailored film properties, using controlled composition or modification by coupling agents, chemical species replacement, or chemical species within pores, provide the chemical selectivity. Single or multiple layers may be provided. 7 figs.

  7. Coatings with controlled porosity and chemical properties

    DOEpatents

    Frye, G.C.; Brinker, C.J.; Doughty, D.H.; Bein, T.; Moller, K.

    1993-07-06

    Coatings and sensors are described having both steric and chemical selectivity. Controlled porosity provides the steric selectivity, whereas chemically tailored film properties, using controlled composition or modification by coupling agents, chemical species replacement, or chemical species within pores, provide the chemical selectivity. Single or multiple layers may be provided.

  8. Robotic weld overlay coatings for erosion control

    SciTech Connect

    Not Available

    1994-11-01

    The erosion of materials by the impact of solid particles has received increasing attention during the past twenty years. Recently, research has been initiated with the event of advanced coal conversion processes in which erosion plays an important role. The resulting damage, termed Solid Particle Erosion (SPE), is of concern primarily because of the significantly increased operating costs which result in material failures. Reduced power plant efficiency due to solid particle erosion of boiler tubes and waterfalls has led to various methods to combat SPE. One method is to apply coatings to the components subjected to erosive environments. Protective weld overlay coatings are particularly advantageous in terms of coating quality. The weld overlay coatings are essentially immune to spallation due to a strong metallurgical bond with the substrate material. By using powder mixtures, multiple alloys can be mixed in order to achieve the best performance in an erosive environment. However, a review of the literature revealed a lack of information on weld overlay coating performance in erosive environments which makes the selection of weld overlay alloys a difficult task. The objective of this project is to determine the effects of weld overlay coating composition and microstructure on erosion resistance. These results will lead to a better understanding of erosion mitigation in CFB`s.

  9. Robotic weld overlay coatings for erosion control

    NASA Astrophysics Data System (ADS)

    The erosion of materials by the impact of solid particles has received increasing attention during the past twenty years. Recently, research has been initiated with the event of advanced coal conversion processes in which erosion plays an important role. The resulting damage, termed Solid Particle Erosion (SPE), is of concern primarily because of the significantly increased operating costs which result in material failures. Reduced power plant efficiency due to solid particle erosion of boiler tubes and waterfalls has led to various methods to combat SPE. One method is to apply coatings to the components subjected to erosive environments. Protective weld overlay coatings are particularly advantageous in terms of coating quality. The weld overlay coatings are essentially immune to spallation due to a strong metallurgical bond with the substrate material. By using powder mixtures, multiple alloys can be mixed in order to achieve the best performance in an erosive environment. However, a review of the literature revealed a lack of information on weld overlay coating performance in erosive environments which makes the selection of weld overlay alloys a difficult task. The objective of this project is to determine the effects of weld overlay coating composition and microstructure on erosion resistance. These results will lead to a better understanding of erosion mitigation in CFB's.

  10. Effect of Lithium PFC Coatings on NSTX Density Control

    SciTech Connect

    Kugel, H W; Bell, M G; Bush, C; Gates, D; Gray, T; Kaita, R; Leblanc, B; Maingi, R; Majeski, R; Mansfield, D; Mueller, D; Raman, R; Roquemore, A L; Sabbagh, S; Skinner, C H; Soukhanovskii, V; Stevenson, T; Zakharov, L

    2006-08-21

    Lithium coatings on the graphite plasma facing components (PFCs) in NSTX are being investigated as a tool for density profile control and reducing the recycling of hydrogen isotopes. Repeated lithium pellet injection into Center Stack Limited and Lower Single Null Ohmic Helium Discharges were used to coat graphite surfaces that had been pre-conditioned with Ohmic Helium Discharges of the same shape to reduce their contribution to hydrogen isotope recycling. The following deuterium NBI reference discharges exhibited a reduction in density by a factor of about 3 for limited and 2 for diverted plasmas respectively, and peaked density profiles. Recently, a lithium evaporator has been used to apply thin coatings on conditioned and unconditioned PFCs. Effects on the plasma density and the impurities were obtained by pre-conditioning the PFCs with ohmic helium discharges, and performing the first deuterium NBI discharge as soon as possible after applying the lithium coating.

  11. PAINT COATINGS: CONTROLLED FIELD AND CHAMBER EXPERIMENTS

    EPA Science Inventory

    To determine the impact of pollution levels on the weathering rates of coatings, laboratory chamber experiments and controlled field exposures at North Carolina and Ohio sites were conducted in such a manner to separate the contributions due to dry deposition, wet deposition, pre...

  12. Selected results for LDEF thermal control coatings

    NASA Technical Reports Server (NTRS)

    Golden, Johnny L.

    1993-01-01

    Several different thermal control coatings were analyzed as part of the Long Duration Exposure Facility (LDEF) Materials Special Investigation Group activity and as part of the Space Environment Effects on Spacecraft Materials Experiment M0003. A brief discussion of the results obtained for these materials is presented.

  13. Controlled Thermal Expansion Coat for Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Brindley, William J. (Inventor); Miller, Robert A. (Inventor); Aikin, Beverly J. M. (Inventor)

    1999-01-01

    A improved thermal barrier coating and method for producing and applying such is disclosed herein. The thermal barrier coating includes a high temperature substrate, a first bond coat layer applied to the substrate of MCrAlX, and a second bond coat layer of MCrAlX with particles of a particulate dispersed throughout the MCrAlX and the preferred particulate is Al2O3. The particles of the particulate dispersed throughout the second bond coat layer preferably have a diameter of less then the height of the peaks of the second bond coat layer, or a diameter of less than 5 microns. The method of producing the second bond coat layer may either include the steps of mechanical alloying of particles throughout the second bond coat layer, attrition milling the particles of the particulate throughout the second bond coat layer, or using electrophoresis to disperse the particles throughout the second bond coat layer. In the preferred embodiment of the invention, the first bond coat layer is applied to the substrate, and then the second bond coat layer is thermally sprayed onto the first bond coat layer. Further, in a preferred embodiment of die invention, a ceramic insulating layer covers the second bond coat layer.

  14. Launch Pad Coatings for Smart Corrosion Control

    NASA Technical Reports Server (NTRS)

    Calle, Luz M.; Hintze, Paul E.; Bucherl, Cori N.; Li, Wenyan; Buhrow, Jerry W.; Curran, Jerome P.; Whitten, Mary C.

    2010-01-01

    Corrosion is the degradation of a material as a result of its interaction with the environment. The environment at the KSC launch pads has been documented by ASM International (formerly American Society for Metals) as the most corrosive in the US. The 70 tons of highly corrosive hydrochloric acid that are generated by the solid rocket boosters during a launch exacerbate the corrosiveness of the environment at the pads. Numerous failures at the pads are caused by the pitting of stainless steels, rebar corrosion, and the degradation of concrete. Corrosion control of launch pad structures relies on the use of coatings selected from the qualified products list (QPL) of the NASA Standard 5008A for Protective Coating of Carbon Steel, Stainless Steel, and Aluminum on Launch Structures, Facilities, and Ground Support Equipment. This standard was developed to establish uniform engineering practices and methods and to ensure the inclusion of essential criteria in the coating of ground support equipment (GSE) and facilities used by or for NASA. This standard is applicable to GSE and facilities that support space vehicle or payload programs or projects and to critical facilities at all NASA locations worldwide. Environmental regulation changes have dramatically reduced the production, handling, use, and availability of conventional protective coatings for application to KSC launch structures and ground support equipment. Current attrition rate of qualified KSC coatings will drastically limit the number of commercial off the shelf (COTS) products available for the Constellation Program (CxP) ground operations (GO). CxP GO identified corrosion detection and control technologies as a critical, initial capability technology need for ground processing of Ares I and Ares V to meet Constellation Architecture Requirements Document (CARD) CxP 70000 operability requirements for reduced ground processing complexity, streamlined integrated testing, and operations phase affordability

  15. Microstructure, Processing, Performance Relationships for High Temperature Coatings

    SciTech Connect

    Thomas M. Lillo; Richard N. Wright; W. David Swank; D.C Haggard; Dennis C. Kunerth; Denis E. Clark

    2008-07-01

    HVOF coating have shown high resistance to corrosion in fossil energy applications and it is generally accepted that mechanical failure, e.g. cracking or spalling, ultimately will determine coating lifetime. The high velocity oxygen-fuel method (HVOF) of applying coatings is one of the most commercially viable and allows the control of various parameters including powder particle velocity and temperature which influence coating properties, such as residual stress, bond coat strength and microstructure. Methods of assessing the mechanical durability of coatings are being developed in order to explore the relationship between HVOF spraying parameters and the mechanical properties of the coating and coating bond strength. The room temperature mechanical strength, as well as the resistance of the coating to cracking/spalling during thermal transients, is of considerable importance. Eddy current, acoustic emission and thermal imaging methods are being developed to detect coating failure during thermal cycling tests and room temperature tensile tests. Preliminary results on coating failure of HVOF FeAl coatings on carbon steel, as detected by eddy current measurements during thermal cycling, are presented. The influence of HVOF coating parameters of iron aluminides - applied to more relevant structural steels, like 316 SS and Grade 91 steel, - on coating durability will be explored once reliable methods for identification of coating failure have been developed.

  16. A Multifunctional Coating for Autonomous Corrosion Control

    NASA Technical Reports Server (NTRS)

    Calle, L. M.; Hintze, P. E.; Li, W.; Buhrow, J. W.; Jolley, S. T.

    2011-01-01

    This slide presentation reviews the effects of corrosion on various structures at the Kennedy Space Center, and the work to discover a corrosion control coating that will be autonomous and will indicate corrosion at an early point in the process. Kennedy Space Center has many environmental conditions that are corrosive: ocean salt spray, heat, humidity, sunlight and acidic exhaust from the Solid Rocket Boosters (SRBs). Presented is a chart which shows the corrosion rates of carbon steel at various locations. KSC has the highest corrosion rates with 42.0 mils/yr, leading the next highest Galeta Point Beach, in the Panama Canal Zone with 27 mils/yr corrosion. A chart shows the changes in corrosion rate with the distance from the ocean. The three types of corrosion protective coatings are described: barrier (passive), Barrier plus active corrosion inhibiting components, and smart. A smart coating will detect and respond actively to changes in its environment in a functional and predictable manner and is capable of adapting its properties dynamically. The smart coating uses microcapsules, particles or liquid drops coated in polymers, that can detect and control the corrosion caused by the environment. The mechanism for a pH sensitive microcapsule and the hydrophobic core microcapsule are demonstrated and the chemistry is reviewed. When corrosion begins, the microcapsule will release the contents of the core (indicator, inhibitor, and self healing agent) in close proximity to the corrosion. The response to a pH increase is demonstrated by a series of pictures that show the breakdown of the microcapsule and the contents release. An example of bolt corrosion is used, as an example of corrosion in places that are difficult to ascertain. A comparison of various coating systems is shown.

  17. Space stable thermal control coatings

    NASA Technical Reports Server (NTRS)

    Harada, Y.

    1976-01-01

    The MOX method, i.e., the use of zinc and titanium oxalate precursors, has the distinct advantages of simple and rapid processing, and of controlled pigment particle size. The chemical identify of TiOX was determined. The Zn/Ti ratio effect on the reflectance spectra and ultraviolet irradiation stability in vacuum for Zn2TiO4 was examined. Optimized processing parameters are considered for reproducibly obtaining a pigment of the most desirable optical properties and behavior.

  18. Final Technical Report - Recovery Act: Organic Coatings as Encapsulants for Low Cost, High Performance PV Modules

    SciTech Connect

    Stuart Hellring; Jiping Shao; James Poole

    2011-12-05

    The objective of this project was to evaluate the feasibility of utilizing PPG's commercial organic coatings systems as efficient, modernized encapsulants for low cost, high performance, thin film photovoltaic modules. Our hypothesis was that the combination of an anticorrosive coating with a more traditional barrier topcoat would mitigate many electrochemical processes that are now responsible for the significant portion of photovoltaic (PV) failures, thereby nullifying the extremely high moisture barrier requirements of currently used encapsulation technology. Nine commercially available metal primer coatings and six commercially available top coatings were selected for screening. Twenty-one different primer/top coat combinations were evaluated. The primer coatings were shown to be the major contributor to corrosion inhibition, adhesion, and barrier properties. Two primer coatings and one top coating were downselected for testing on specially-fabricated test modules. The coated test modules passed initial current leakage and insulation testing. Damp Heat testing of control modules showed visible corrosion to the bus bar metal, whereas the coated modules showed none. One of the primer/top coat combinations retained solar power performance after Damp Heat testing despite showing some delamination at the EVA/solar cell interface. Thermal Cycling and Humidity Freeze testing resulted in only one test module retaining its power performance. Failure modes depended on the particular primer/top coating combination used. Overall, this study demonstrated that a relatively thin primer/top coating has the potential to replace the potting film and backsheet in crystalline silicon-based photovoltaic modules. Positive signals were received from commercially available coatings developed for applications having performance requirements different from those required for photovoltaic modules. It is likely that future work to redesign and customize these coatings would result in a

  19. Variable anodic thermal control coating on aluminum

    NASA Technical Reports Server (NTRS)

    Duckett, R. J.; Gilliland, C. S.

    1983-01-01

    A variable thermal control coating (modified chromic acid anodizing) has been developed to meet the needs for the thermal control of spacecraft. This coating, with controlled variable ranges of 0.10 to 0.72 thermal emittance and 0.2 to 0.4 solar absorptance, allows the user to select any value of thermal emittance and solar absorptance within the range specified and obtain both values within + or - 0.02. Preliminary solar stability has shown less than 15 percent degradation over 2000 hours of vacuum solar exposure. The technique has been determined to be sensitive to the parameters of voltage, rate of voltage application, time, temperature, acid concentration, and material pretreatment.

  20. 49 CFR 192.461 - External corrosion control: Protective coating.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false External corrosion control: Protective coating... for Corrosion Control § 192.461 External corrosion control: Protective coating. (a) Each external protective coating, whether conductive or insulating, applied for the purpose of external corrosion...

  1. 49 CFR 192.461 - External corrosion control: Protective coating.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false External corrosion control: Protective coating... for Corrosion Control § 192.461 External corrosion control: Protective coating. (a) Each external protective coating, whether conductive or insulating, applied for the purpose of external corrosion...

  2. 49 CFR 192.461 - External corrosion control: Protective coating.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false External corrosion control: Protective coating... for Corrosion Control § 192.461 External corrosion control: Protective coating. (a) Each external protective coating, whether conductive or insulating, applied for the purpose of external corrosion...

  3. 49 CFR 192.461 - External corrosion control: Protective coating.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false External corrosion control: Protective coating... for Corrosion Control § 192.461 External corrosion control: Protective coating. (a) Each external protective coating, whether conductive or insulating, applied for the purpose of external corrosion...

  4. Dissipation factor as a predictor of anodic coating performance

    DOEpatents

    Panitz, Janda K. G.

    1995-01-01

    A dissipation factor measurement is used to predict as-anodized fixture performance prior to actual use of the fixture in an etching environment. A dissipation factor measurement of the anodic coating determines its dielectric characteristics and correlates to the performance of the anodic coating in actual use. The ability to predict the performance of the fixture and its anodized coating permits the fixture to be repaired or replaced prior to complete failure.

  5. HIGH TEMPERATURE OXIDATION PERFORMANCE OF ALUMINIDE COATINGS

    SciTech Connect

    Pint, B.A.; Zhang, Y.; Haynes, J.A.; Wright, I.G.

    2003-04-22

    In order to determine the potential benefits and limitations of aluminide coatings, coatings made by chemical vapor deposition (CVD) on Fe- and Ni-base alloy substrates are being evaluated in various high-temperature environments. Testing of coatings on representative ferritic (Fe-9Cr-1Mo) and austenitic (type 304L stainless steel) alloys has found that high frequency thermal cycling (1h cycle time) can significantly degrade the coating. Based on comparison with similar specimens with no thermal cycling or a longer cycle time (100h), this degradation was not due to Al loss from the coating but most likely because of the thermal expansion mismatch between the coating and the substrate. Several coated Ni-base alloys were tested in a high pressure (20atm) steam-CO2 environment for the ZEST (zero-emission steam turbine) program. Coated specimens showed less mass loss than the uncoated specimens after 1000h at 900 C and preliminary characterization examined the post-test coating structure and extent of attack.

  6. Microstructure, Processing, Performance Relationships for High Temperature Coatings

    SciTech Connect

    Thomas M. Lillo

    2011-04-01

    This work evaluates the suitability of iron aluminide coatings for use in high temperature fossil fuel combustion environments, such as boiler applications. The coatings are applied using High Velocity Oxy-Fuel (HVOF) thermal spray techniques. Iron aluminide coatings, with the nominal composition of Fe3Al, were applied to various high temperature structural materials (316 Stainless Steel, 9Cr-1Mo steel and Inconel 600) that typically lack inherent resistance to environmental degradation found in fossil fuel combustion atmospheres. Coating/substrate combinations were subjected to thermal cycling to evaluate the effect of HVOF parameters, coating thickness, substrate material and substrate surface roughness on the resistance to coating delamination and cracking. It was found that substrate surface roughness had a profound influence on the performance of a given substrate/coating system and that surface preparation techniques will need to be tailored to the specific substrate material. Also, higher particle velocity during HVOF thermal spray deposition of the iron aluminide coatings tended to result in better-performing coating/substrate systems with less delamination at the coating/substrate interface. Some combinations of HVOF parameters, coating thickness and substrate materials were found to perform extremely well even at temperatures up to 900oC. However, in some cases, substantial reactions at the interface were observed.

  7. Performance of CVR coatings for PBR fuels

    SciTech Connect

    Adams, J.W.; Barletta, R.E.; Svandrlik, J.; Vanier, P.E.

    1993-12-31

    As part of the component development process for the particle bed reactor (PBR), it is necessary to develop coatings for fuel particles which will be time and temperature stable. These coatings must not only protect the particle from attack by the hydrogen coolant, but must also help to maintain the bed in a coolable geometry and mitigate against fission product release. In order to develop these advanced coatings, a process to produce chemical vapor reaction (CVR) coatings on fuel for PBRs has been developed. The initial screening tests for these coatings consisted of testing in flowing hot hydrogen at one atmosphere. Surrogate fuel particles consisting of pyrolytic graphite coated graphite particles have been heated in flowing hydrogen at constant temperature. The carbon loss from these particles was measured as a function of time. Exposure temperatures ranging from 2,500 to 3,000 K were used and samples were exposed for up to 14 minutes in a cyclical fashion, cooling to room temperature between exposures. The rate of weight loss measured as a function of time is compared to that from other tests of coated materials under similar conditions. Microscopic examination of the coatings before and after exposure was also conducted and these results are presented.

  8. Analyzing the performance of diamond-coated micro end mills.

    SciTech Connect

    Torres, C. D.; Heaney, P. J.; Sumant, A. V.; Hamilton, M. A.; Carpick, R. W.; Pfefferkorn, F. E.; Univ. of Wisconsin at Madison; Univ. of Pennsylvania

    2009-06-01

    A method is presented to improve the tool life and cutting performance of 300 {micro}m diameter tungsten carbide (WC) micro end mills by applying thin (<300 nm) fine-grained diamond (FGD) and nanocrystalline diamond (NCD) coatings using the hot-filament chemical vapor deposition (HF-CVD) process. The performance of the diamond-coated tools has been evaluated by comparing their performance in dry slot milling of 6061-T6 aluminum against uncoated WC micro end mills. Tool wear, coating integrity, and chip morphology were characterized using SEM and white light interferometry. The initial test results show a dramatic improvement in the tool integrity (i.e., corners not breaking off), a lower wear rate, no observable adhesion of aluminum to the diamond-coated tool, and a significant reduction in the cutting forces (>50%). Reduction of the cutting forces is attributed to the low friction and adhesion of the diamond coating. However, approximately 80% of the tools coated with the larger FGD coatings failed during testing due to delamination. Additional machining benefits were attained for the NCD films, which was obtained by using a higher nucleation density seeding process for diamond growth. This process allowed for thinner, smaller grained diamond coatings to be deposited on the micro end mills, and enabled continued operation of the tool even after the integrity of the diamond coating had been compromised. As opposed to the FGD-coated end mills, only 40% of the NCD-tools experienced delamination issues.

  9. Advanced Low Conductivity Thermal Barrier Coatings: Performance and Future Directions

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    2008-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and performance will be emphasized. Advanced thermal barrier coatings have been developed using a multi-component defect clustering approach, and shown to have improved thermal stability and lower conductivity. The coating systems have been demonstrated for high temperature combustor applications. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the toughened thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion, impact and high heat-flux damage mechanisms of the thermal barrier coatings will also be described.

  10. Skylab D024 thermal control coatings and polymeric films experiment

    NASA Technical Reports Server (NTRS)

    Lehn, William L.; Hurley, Charles J.

    1992-01-01

    The Skylab D024 Thermal Control Coatings and Polymeric Films Experiment was designed to determine the effects of the external Skylab space environment on the performance and properties of a wide variety of selected thermal control coatings and polymeric films. Three duplicate sets of thermal control coatings and polymeric films were exposed to the Skylab space environment for varying periods of time during the mission. The specimens were retrieved by the astronauts during extravehicular activities (EVA) and placed in hermetically sealed return containers, recovered, and returned to the Wright Laboratory/Materials Laboratory/WPAFB, Ohio for analysis and evaluation. Postflight analysis of the three sets of recovered thermal control coatings indicated that measured changes in specimen thermo-optical properties were due to a combination of excessive contamination and solar degradation of the contaminant layer. The degree of degradation experienced over-rode, obscured, and compromised the measurement of the degradation of the substrate coatings themselves. Results of the analysis of the effects of exposure on the polymeric films and the contamination observed are also presented. The D024 results were used in the design of the LDEF M0003-5 Thermal Control Materials Experiment. The results are presented here to call to the attention of the many other LDEF experimenters the wealth of directly related, low earth orbit, space environmental exposure data that is available from the ten or more separate experiments that were conducted during the Skylab mission. Results of these experiments offer data on the results of low altitude space exposure on materials recovered from space with exposure longer than typical STS experiments for comparison with the LDEF results.

  11. Tribological performance of DLC coatings on UHMWPE

    NASA Astrophysics Data System (ADS)

    Martínez-Nogués, V.; Medel, F. J.; Mariscal, M. D.; Endrino, J. L.; Krzanowski, J.; Yubero, F.; Puértolas, J. A.

    2010-11-01

    Diamond like carbon (DLC) coatings were deposited by several methods (ion beam assisted evaporation, magnetron sputtering, filter cathodic arc, and plasma enhanced chemical vapor deposition) onto medical grade ultra-high-molecular weight polyethylene (UHMWPE) discs. The chemical characteristics and mechanical properties of the deposited DLC coatings were studied by Raman spectroscopy and nanoindentation, respectively. In addition, a set of tribological tests was conducted at human body temperature and under bovine serum lubrication against alumina balls. After testing, wear tracks were both visually inspected and documented using confocal microscopy. Visual inspection of the wear tracks confirmed that the DLC coatings were completely removed in all cases, the only exception being the DLC coating prepared by magnetron sputtering with thickness about 0.5 microns. Although this type of DLC coating exhibited the highest friction coefficient, and therefore it suggested a somewhat lower resistance to abrasive/adhesive wear conditions, no evidence of cracking or delamination was observed after the high contact pressure wear testing. This fact points out a good substrate-coating adhesion, and confirms magnetron sputtered DLC as a potential coating for orthopaedic applications.

  12. Cellulose Nanocrystals--Bioactive Glass Hybrid Coating as Bone Substitutes by Electrophoretic Co-deposition: In Situ Control of Mineralization of Bioactive Glass and Enhancement of Osteoblastic Performance.

    PubMed

    Chen, Qiang; Garcia, Rosalina Pérez; Munoz, Josemari; Pérez de Larraya, Uxua; Garmendia, Nere; Yao, Qingqing; Boccaccini, Aldo R

    2015-11-11

    Surface functionalization of orthopedic implants is being intensively investigated to strengthen bone-to-implant contact and accelerate bone healing process. A hybrid coating, consisting of 45S5 bioactive glass (BG) individually wrapped and interconnected with fibrous cellulose nanocrystals (CNCs), is deposited on 316L stainless steel from aqueous suspension by a one-step electrophoretic deposition (EPD) process. Apart from the codeposition mechanism elucidated by means of zeta-potential and scanning electron microscopy measurements, in vitro characterization of the deposited CNCs-BG coating in simulated body fluid reveals an extremely rapid mineralization of BG particles on the coating (e.g., the formation of hydroxyapatite crystals layer after 0.5 day). A series of comparative trials and characterization methods were carried out to comprehensively understand the mineralization process of BG interacting with CNCs. Furthermore, key factors for satisfying the applicability of an implant coating such as coating composition, surface topography, and adhesion strength were quantitatively investigated as a function of mineralization time. Cell culture studies (using MC3T3-E1) indicate that the presence of CNCs-BG coating substantially accelerated cell attachment, spreading, proliferation, differentiation, and mineralization of extracellular matrix. This study has confirmed the capability of CNCs to enhance and regulate the bioactivity of BG particles, leading to mineralized CNCs-BG hybrids for improved bone implant coatings. PMID:26460819

  13. A performance and reliability model for thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Batakis, A. P.

    1985-01-01

    A modeling technique for predicting the performance and reliability of TBC's is being developed at Solar Turbines Incorporated. The concept combines experimental coating property data with finite element analyses to predict the thermal and mechanical behavior of coating systems in service. A key feature of Solar's approach is the use of a four point flexure test to estimate coating strength distributions and to predict coating failure probability. This model was used to evaluate the effect of physical variations on coating performance in high heat flux rocket engine applications for NASA. Current work, promoted by Caterpillar Tractor Company for diesel engine applications, is being conducted to measure coating strength as a function of temperature, and future work will document strength degradation with time at temperature. Solar's interest lies in the application of TBCs to gas turbine engine components.

  14. Optical interference coatings for improved luminaire performance. Final report

    SciTech Connect

    Rubins, H.L.

    1981-01-01

    An interior broadbeam HID uplight and an upstream roadway luminaire were developed to demonstrate that optical coated luminaire components can improve the visual effectiveness and energy efficiency of a lighting system. Optical coated reflectors and flat lens covers were very effective in the development of new improved lighting techniques. The coatings reduce reflection and transmission losses, opening the door to new design options for improving lighting performance and saving energy.

  15. Liquid phase coating to produce controlled-release alginate microspheres.

    PubMed

    Chan, Lai Wah; Liu, Xiaohua; Heng, Paul Wan Sia

    2005-12-01

    This study explored a liquid phase coating technique to produce polymethyl methacrylate (PMMA)-coated alginate microspheres. Alginate microspheres with a mean diameter of 85.6 microm were prepared using an emulsification method. The alginate microspheres, as cores, were then coated with different types of PMMA by a liquid phase coating technique. The release characteristics of these coated microspheres in simulated gastric (SGF) and intestinal (SIF) fluids and the influence of drug load on encapsulation efficiency were studied. The release of paracetamol, as a model hydrophilic drug, from the coated microspheres in SGF and SIF was greatly retarded. Release rates of Eudragit RS100-coated microspheres in SGF and SIF were similar as the rate-controlling polymer coat was insoluble in both media. Drug release from Eudragit S100-coated microspheres was more sustained in SGF than in SIF, due to the greater solubility of the coating polymer in media with pH greater than 7.0. The drug release rate was affected by the core:coat ratio. Drug release from the coated microspheres was best described by the Higuchi's square root model. The liquid phase coating technique developed offers an efficient method of coating small microspheres with markedly reduced drug loss and possible controlled drug release. PMID:16423760

  16. Correlation of Predicted and Observed Optical Properties of Multilayer Thermal Control Coatings

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.

    1998-01-01

    Thermal control coatings on spacecraft will be increasingly important, as spacecraft grow smaller and more compact. New thermal control coatings will be needed to meet the demanding requirements of next generation spacecraft. Computer programs are now available to design optical coatings and one such program was used to design several thermal control coatings consisting of alternating layers of WO3 and SiO2. The coatings were subsequently manufactured with electron beam evaporation and characterized with both optical and thermal techniques. Optical data were collected in both the visible region of the spectrum and the infrared. Predictions of solar absorptance and infrared emittance were successfully correlated to the observed thermal control properties. Functional performance of the coatings was verified in a bench top thermal vacuum chamber.

  17. Radiation Control Coatings Installed on Federal Buildings at Tyndall Air Force Base

    SciTech Connect

    Kaba, R.L.; Petrie, T.W.

    1999-03-16

    The technical objectives of this CRADA comprise technology deployment and energy conservation efforts with the radiation control coatings industry and the utility sector. The results of this collaboration include a high-level data reporting, analysis and management system to support the deployment efforts. The technical objectives include successfully install, commission, operate, maintain and document the performance of radiation control coatings on roofs at Tyndall AFB and the Buildings Technology Center at the Oak Ridge National Laboratory; determine the life cycle savings that can be achieved by using radiation control coatings on entire roofs at Tyndall AFB, based on documented installed cost and operating maintenance costs with and without the coatings; determine if any specific improvements are required in the coatings before they can be successfully deployed in the federal sector; determine the most effective way to facilitate the widespread and rapid deployment of radiation control coatings in the federal sector; and clearly define any barriers to deployment.

  18. Microencapsulation of Self Healing Agents for Corrosion Control Coatings

    NASA Technical Reports Server (NTRS)

    Jolley, S. T.; Li, W.; Buhrow, J. W.; Calle, L. M.

    2011-01-01

    Corrosion, the environmentally induced degradation of materials, is a very costly problem that has a major impact on the global economy. Results from a 2-year breakthrough study released in 2002 by the U.S. Federal Highway Administration (FHWA) showed that the total annual estimated direct cost associated with metallic corrosion in nearly every U.S. industry sector was a staggering $276 billion, approximately 3.1% of the nation's Gross Domestic Product (GOP). Corrosion protective coatings are widely used to protect metallic structures from the detrimental effects of corrosion but their effectiveness can be seriously compromised by mechanical damage, such as a scratch, that exposes the metallic substrate. The incorporation of a self healing mechanism into a corrosion control coating would have the potential to significantly increase its effectiveness and useful lifetime. This paper describes work performed to incorporate a number of microcapsule-based self healing systems into corrosion control coatings. The work includes the preparation and evaluation of self-healing systems based on curable epoxy, acrylate, and siloxane resins, as well as, microencapsulated systems based on passive, solvent born, healing agent delivery. The synthesis and optimization of microcapsule-based self healing systems for thin coating (less than 100 micron) will be presented.

  19. Development of Silane Hydrolysate Binder for Thermal-Control Coatings

    NASA Technical Reports Server (NTRS)

    Patterson, W. J.

    1983-01-01

    Technical report describes theoretical and experimental development of methyltriethoxysilane (MTES) hydrolysate binder for white, titanium dioxidepigmented thermal-control coatings often needed on satellites. New coating is tougher and more abrasion-resistant than conventional coating, S-13G, which comprises zinc oxide in hydroxyl-therminated dimethylsiloxane binder.

  20. Phosphoric chemical conversion coating with excellent wax-repellent performance

    NASA Astrophysics Data System (ADS)

    Guo, Yuzhen; Li, Weiping; Zhu, Liqun; Wang, Zhiwei; Liu, Huicong

    2012-10-01

    Wax deposition on pipelines is a serious problem for the production of crude oil. In this paper, phosphoric chemical conversion coatings were exploited to solve the problem. The chemical conversion coatings were fabricated on carbon substrate by surface modification technology at different temperature. A self-designed wax deposition apparatus based on cold-finger was used to study the wax-repellent properties of coatings, which indicated that all chemical conversion coatings showed superior wax-repellent performance to bare carbon substrate and the wax deposition reduction value of 80-95% was achieved by the chemical conversion coating obtained at room temperature. The microstructure and composition of coatings were evaluated by SEM and XRD, revealing that there existed much difference in the content of Zn3(PO4)2(H2O)4 phase and the microstructure among different coatings. The contact angle results measured on a contact angle meter showed that all coatings belonged to hydrophilic surface. And the study on the wetting behavior of Zn3(PO4)2(H2O)4 phase suggested that the water wetting property of coating was a key factor for suppressing wax deposition and the weak affinity between coating and wax also played an important role.

  1. Metallized coatings for corrosion control of Naval ship structures and components

    NASA Technical Reports Server (NTRS)

    1983-01-01

    In attempting to improve corrosion control, the U.S. Navy has undertaken a program of coating corrosion-susceptible shipboard components with thermally sprayed aluminum. In this report the program is reviewed in depth, including examination of processes, process controls, the nature and properties of the coatings, nondestructive examination, and possible hazards to personnel. The performance of alternative metallic coating materials is also discussed. It is concluded that thermally sprayed aluminum can provide effective long-term protection against corrosion, thereby obviating the need for chipping of rust and repainting by ship personnel. Such coatings are providing excellent protection to below-deck components such as steam valves, but improvements are needed to realize the full potential of coatings for above-deck service. Several recommendations are made regarding processes, materials, and research and development aimed at upgrading further the performance of these coatings.

  2. Advanced Coatings Enabling High Performance Instruments for Astrophysics Missions

    NASA Astrophysics Data System (ADS)

    Nikzad, Shouleh

    We propose a three-year effort to develop techniques for far-ultraviolet (FUV) and ultraviolet coatings both as reflective optics coatings and as out-of-band-rejection (solar-blind) filters that will have a dramatic effect on the throughput and efficiency of instruments. This is an ideal time to address this problem. On the one hand, exciting new science questions posed in UV and optical realm place exacting demands on instrument capabilities far beyond HST-COS, FUSE, and GALEX with large focal plane arrays and high efficiency requirements. And on the other hand, the development of techniques and process such as atomic layer deposition with its atomically precise capability and nano-engineered materials approach enables us to address the challenging materials issues in the UV where interaction of photons and matter happen in the first few nanometers of the material surface. Aluminum substrates with protective overlayers (typically XFy, where X = Li, Mg, or Ca) have been the workhorse of reflective coatings for ultraviolet and visible instruments; however, they have demonstrated severe limitations. The formation of oxide at the Al-XFy interface and thick protective layers both affect the overall optical performance, leading to diminished reflection at shorter wavelengths. To address these long-standing shortcomings of coatings, we will use our newly developed processes and equipment to produce high-quality single- and multi-layer films of a variety of dielectrics and metals deposited with nano-scale control. JPL s new ALD system affords high uniformity, low oxygen background, good plasma processes, and precise temperature control, which are vital to achieving the large scale, uniform, and ultrathin films that are free of oxygen at interfaces. For example, ALD-grown aluminum can be protected using our newly developed chemistry for ALD magnesium fluoride. Our work will verify that the ALD technique reliably prevents the oxidation of aluminum, and will subsequently be

  3. 49 CFR 192.461 - External corrosion control: Protective coating.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... protective coating, whether conductive or insulating, applied for the purpose of external corrosion control... is an electrically insulating type must also have low moisture absorption and high...

  4. Microstructure, Processing, Performance Relationships for High Temperature Coatings

    SciTech Connect

    Thomas Lillo; Richard Wright

    2009-05-01

    HVOF coatings have shown high resistance to corrosion in fossil energy applications and it is generally accepted that mechanical failure, e.g. cracking or spalling, ultimately will determine coating lifetime. The high velocity oxygen-fuel method (HVOF) for applying coatings is one of the most commercially viable and allows the control of various parameters including powder particle velocity and temperature which influence coating properties, such as residual stress, bond coat strength and microstructure. The mechanical durability of coatings is being assessed using a dual eddy current coil method to monitor crack formation in real time during thermal cycling. Absolute impedence signals from two coils, which interrogate two different areas on the sample, are collected. Crack detection can be determined from the differential signal generated from these absolute signals. The coils are operated at two different frequencies, resulting in two differential signals used for crack detection. Currently this crack detection method is being used to elucidate the influence of thermal cycling temperature and coating thickness on cracking. Recent results (cycles to failure) will be presented for FeAl coatings thermally sprayed (HVOF) onto carbon steel to two coating thicknesses (160 microns and 250 microns thick) and subsequently cycled at temperatures up to 700oC. Thinner coatings exhibit greater resistance to cracking. Ultimately the resistance to cracking will be used to explore the relationship between HVOF spraying parameters, the mechanical properties of the coating and coating bond strength to develop optimized thermal spray parameters. To this end thermal spray coatings (FeAl and Fe3Al) have been applied to additional alloy substrates (Grade 91 steel, 316 SS, etc.) relevant to the fossil industry. Future plans also include a direct comparison to conventional weld overlay coatings currently used in the industry as well as exploration of new coatings. The room temperature

  5. Experimental design and performance analysis of alumina coatings deposited by a detonation spray process

    NASA Astrophysics Data System (ADS)

    Saravanan, P.; Selvarajan, V.; Joshi, S. V.; Sundararajan, G.

    2001-01-01

    The increasing demands for high-quality coatings has made it inevitable that the surface coating industry would put more effort into precisely controlling the coating process. Statistical design of experiments is an effective method for finding the optimum spray parameters to enhance thermal spray coating properties. In the present investigation, an attempt is made to produce high-quality alumina (Al2O3) coatings by optimizing the detonation spray process parameters following a (L16-24) factorial design approach. The process parameters that were varied include the fuel ratio, carrier gas flow rate, frequency of detonations and spray distance. The coating characteristics were quantified with respect to roughness, hardness and porosity. The performance of the coatings was quantitively evaluated using erosion, abrasion and sliding wear testing. Through statistical analysis of the experimental results, performed by the ANOVA method, the significance of each process parameter together with an optimal variable combination was obtained for the desired coating attributes. Confirmation experiments were conducted to verify the optimal spray parameter combination, which clearly showed the possibility of producing high-quality Al2O3 coatings.

  6. Effects of calcium phosphate composition in sputter coatings on in vitro and in vivo performance.

    PubMed

    Urquia Edreira, Eva R; Wolke, Joop G C; Aldosari, Abdullah AlFarraj; Al-Johany, Sulieman S; Anil, Sukumaran; Jansen, John A; van den Beucken, Jeroen J J P

    2015-01-01

    Calcium phosphate (CaP) ceramic coatings have been used to enhance the biocompatibility and osteoconductive properties of metallic implants. The chemical composition of these ceramic coatings is an important parameter, which can influence the final bone performance of the implant. In this study, the effect of phase composition of CaP-sputtered coatings was investigated on in vitro dissolution behavior and in vivo bone response. Coatings were prepared by a radio frequency (RF) magnetron sputtering technique; three types of CaP target materials were used to obtain coatings with different stoichiometry and calcium to phosphate ratios (hydroxyapatite (HA), α-tricalciumphosphate (α-TCP), and tetracalciumphosphate (TTCP)) were compared with non-coated titanium controls. The applied ceramic coatings were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and inductively coupled plasma optical emission spectroscopy. The in vitro dissolution/precipitation of the CaP coatings was evaluated using immersion tests in simulated body fluid (SBF). To mimic the in vivo situation, identical CaP coatings were also evaluated in a femoral condyle rabbit model. TCPH and TTCPH showed morphological changes during 4-week immersion in SBF. The results of bone implant contact (BIC) and peri-implant bone volume (BV) showed a similar response for all experimental coatings. An apparent increase in tartrate resistant acid phosphatase (TRAP) positive staining was observed in the peri-implant region with decreasing coating stability. In conclusion, the experimental groups showed different coating properties when tested in vitro and an apparent increase in bone remodeling with increasing coating dissolution in vivo. PMID:24659523

  7. Microfluidic Controlled Conformal Coating of Particles

    NASA Astrophysics Data System (ADS)

    Tsai, Scott; Wexler, Jason; Wan, Jiandi; Stone, Howard

    2011-11-01

    Coating flows are an important class of fluid mechanics problems. Typically a substrate is coated with a moving continuous film, but it is also possible to consider coating of discrete objects. In particular, in applications involving coating of particles that are useful in drug delivery, the coatings act as drug-carrying vehicles, while in cell therapy a thin polymeric coating is required to protect the cells from the host's immune system. Although many functional capabilities have been developed for lab-on-a-chip devices, a technique for coating has not been demonstrated. We present a microfluidic platform developed to coat micron-size spheres with a thin aqueous layer by magnetically pulling the particles from the aqueous phase to the non-aqueous phase in a co-flow. Coating thickness can be adjusted by the average fluid speed and the number of beads encapsulated inside a single coat is tuned by the ratio of magnetic to interfacial forces acting on the beads.

  8. A minimal model for flow control on an aerofoil using a poro-elastic coating

    NASA Astrophysics Data System (ADS)

    Venkataraman, Divya; Bottaro, Alessandro; Govindarajan, Rama

    2014-05-01

    A minimal model is obtained for vortex-shedding from an aerofoil with a porous coating of flow-compliant feather-like actuators, in order to better understand this passive way to achieve flow control. This model is realized by linearly coupling a minimal-order model for vortex-shedding from the same aerofoil without any such coating with an equation for the poro-elastic coating, here modelled as a linear damped oscillator. The various coefficients in this model, derived using perturbation techniques, aid in our understanding of the physics of this fluid-structure interaction problem. The minimal model for a coated aerofoil indicates the presence of distinct regimes that are dependent on the flow and coating characteristics. The models and the parametric studies performed provide insight into the selection of optimal coating parameters, to enable flow control at low Reynolds numbers.

  9. Tandem cylinder aerodynamic sound control using porous coating

    NASA Astrophysics Data System (ADS)

    Liu, Hanru; Azarpeyvand, Mahdi; Wei, Jinjia; Qu, Zhiguo

    2015-01-01

    This study is concerned with the application of porous coatings as a passive flow control method for reducing the aerodynamic sound from tandem cylinders. The aim here is to perform a parametric proof-of-concept study to investigate the effectiveness of porous treatment on bare tandem cylinders to control and regularize the vortex shedding and flow within the gap region between the two bluff bodies, and thereby control the aerodynamic sound generation mechanism. The aerodynamic simulations are performed using 2D transient RANS approach with k - ω turbulence model, and the acoustic computations are carried out using the standard Ffowcs Williams-Hawkings (FW-H) acoustic analogy. Numerical flow and acoustic results are presented for bare tandem cylinders and porous-covered cylinders, with different porosities and thicknesses. Experimental flow and acoustic data are also provided for comparison. Results show that the proper use of porous coatings can lead to stabilization of the vortex shedding within the gap region, reduction of the vortex shedding interaction with the downstream body, and therefore the generation of tonal and broadband noise. It has also been observed that the magnitude and the frequency of the primary tone reduce significantly as a result of the flow regularization. The proposed passive flow-induced noise and vibration control method can potentially be used for other problems involving flow interaction with bluff bodies.

  10. Thin film thermoelectric devices as thermal control coatings: A study

    NASA Technical Reports Server (NTRS)

    Clemons, J. M.; Krupnick, A. C.

    1973-01-01

    Peltier effect, Thomson effect, and Seeback effect are utilized in design of thermal control coating that serves as versatile means for controlling heat absorbed and radiated by surface. Coatings may be useful in extreme temperature environment enclosures or as heat shields.

  11. Visual and energy performance of switchable windows with antireflection coatings

    SciTech Connect

    Jonsson, Andreas; Roos, Arne

    2010-08-15

    The aim of this project was to investigate how the visual appearance and energy performance of switchable or smart windows can be improved by using antireflective coatings. For this study clear float glass, low-e glass and electrochromic glass were treated with antireflection (AR) coatings. Such a coating considerably increases the transmittance of solar radiation in general and the visible transmittance in particular. For switchable glazing based on absorptive electrochromic layers in their dark state it is necessary to use a low-emissivity coating on the inner pane of a double glazed window in order to reject the absorbed heat. In principle all surfaces can be coated with AR coatings, and it was shown that a thin AR coating on the low-e surface neither influences the thermal emissivity nor the U-value of the glazing. The study showed that the use of AR coatings in switchable glazing significantly increases the light transmittance in the transparent state. It is believed that this is important for a high level of user acceptance of such windows. (author)

  12. High performance radiation curable hybrid coatings

    NASA Astrophysics Data System (ADS)

    Nik Salleh, Nik Ghazali; Sofian Alias, Mohd; Gläsel, H.-J.; Mehnert, R.

    2013-03-01

    Radiation curing is one of the most effective processes to produce rapidly composite materials at ambient temperature. Silica nanoparticles can be introduced into radiation curable resins to produce scratch and abrasion resistant materials, which can be used as sealants or clear coatings. In preparation of radiation cured polymeric composites for wood based products such as medium density fiberboard etc., we synthesized radiation curable silico-organic nanoparticles from silica/acrylates system. These nano-sized silica particles were used as fillers. Epoxy acrylates was used as prepolymer while pentaerythritol triacrylate and tetraacrylate (PETIA) was used as monomer. The acrylated epoxy resin synthesized from palm oil based product (EPOLA) i.e. bio-renewable raw materials was also used in the system. The surface of the silica was chemically modified to improve the embedding of the filler within the acrylate matrix. Modification of the silica surface using silane was done to overcome the problem of incompatibility with acrylates at high silica contents. The nature of the nanoparticles is now changed from hydrophilic to organophilic. In these investigations, we use low energy electron beam accelerator to initiate polymerization and interaction at the interface between the nanoparticles and the monomeric materials. These polymerization active nanoparticles were obtained by heterogeneous hydrolytic condensation of the silane to the silanol groups of the silica particles. Formulations useful for technical coating processes could be prepared and these composite materials showed highly improved mechanical properties. They also provided a high network density whilst the coatings remain transparent. These polymeric nanocomposites show excellent resistances toward abrasion properties including scratch property as compared to pure acrylates.

  13. Repair of high performance multilayer coatings

    SciTech Connect

    Gaines, D.P. . Dept. of Physics and Astronomy); Ceglio, N.M. ); Vernon, S.P. ); Krumrey, M.; Mueller, P. . VUV Radiometric Lab.)

    1991-07-01

    Fabrication and environmental damage issues may require that the multilayer x-ray reflection coatings used in soft x-ray projection lithography be replaced or repaired. Two repair strategies were investigated. The first was to overcoat defective multilayers with a new multilayer. The feasibility of this approach was demonstrated by depositing high reflectivity (61% at 130 {Angstrom}) molybdenum silicon (Mo/Si) multilayers onto fused silica figured optics that had already been coated with a Mo/Si multilayer. Because some types of damage mechanisms and fabrication errors are not repairable by this method, a second method of repair was investigated. The multilayer was stripped from the optical substrate by etching a release layer which was deposited onto the substrate beneath the multilayer. The release layer consisted of a 1000 {Angstrom} aluminum film deposited by ion beam sputtering or by electron beam evaporation, with a 300 {Angstrom} SiO{sub 2} protective overcoat. The substrates were superpolished zerodur optical flats. The normal incidence x-ray reflectivity of multilayers deposited on these aluminized substrates was degraded, presumably due to the roughness of the aluminum films. Multilayers, and the underlying release layers, have been removed without damaging the substrates.

  14. Repair of high-performance multilayer coatings

    NASA Astrophysics Data System (ADS)

    Gaines, David P.; Ceglio, Natale M.; Vernon, Stephen P.; Krumrey, Michael K.; Mueller, Peter

    1992-01-01

    Fabrication and environmental damage issues may require that the multilayer x-ray reflection coatings used in soft x-ray projection lithography be replaced or repaired. Two repair strategies were investigated. The first was to overcoat defective multilayers with a new multilayer. The feasibility of this approach was demonstrated by depositing high reflectivity (61% at 130 A) molybdenum silicon (Mo/Si) multilayers onto fused silica figured optics that had already been coated with a Mo/Si multilayer. Because some types of damage mechanisms and fabrication errors are not repairable by this method, a second method of repair was investigated. The multilayer was stripped from the optical substrate by etching a release layer which was deposited onto the substrate beneath the multilayer. The release layer consisted of a 1000 A aluminum film deposited by ion beam sputtering or by electron beam evaporation, with a 300 A SiO protective overcoat. The substrates were superpolished zerodur optical flats. The normal incidence x-ray reflectivity of multilayers deposited on these aluminized substrates was degraded, presumably due to roughness of the aluminum films. Multilayers, and the underlying release layers, have been removed without damaging the substrates.

  15. A Review of Tribological Coatings for Control Drive Mechanisms in Space Reactors

    SciTech Connect

    CJ Larkin; JD Edington; BJ Close

    2006-02-21

    Tribological coatings must provide lubrication for moving components of the control drive mechanism for a space reactor and prevent seizing due to friction or diffusion welding to provide highly reliable and precise control of reflector position over the mission lifetime. Several coatings were evaluated based on tribological performance at elevated temperatures and in ultrahigh vacuum environments. Candidates with proven performance in the anticipated environment are limited primarily to disulfide materials. Irradiation data for these coatings is nonexistent. Compatibility issues between coating materials and structural components may require the use of barrier layers between the solid lubricant and structural components to prevent deleterious interactions. It would be advisable to consider possible lubricant interactions prior to down-selection of structural materials. A battery of tests was proposed to provide the necessary data for eventual solid lubricant/coating selection.

  16. Performance of microprocessor controllers

    SciTech Connect

    Gates, R.S.; Turner, L.W.; Overhults, D.G. . Dept. of Agricultural Engineering)

    1992-01-01

    United States animal production systems are at the threshold of a major new method for daily management of environmental control -- the integrated microprocessor-based environmental control system. Widespread adoption of this technology has the potential for dramatic improvement in production efficiencies through lower management costs, improved energy savings, and better feed conversion efficiencies. However, the technical problems of transient surge protection and appropriate mechanical backup systems have not been adequately addressed by the industry. The goals of this research were to identify the degree to which transient surge protection was being provided by current manufacturers, and to illustrate the implementation of microprocessor environmental control systems with mechanical backup. Transient open circuit over-voltage tests (ANSI/IEEE C62.41-1980) were performed on 16 environmental control units: a maximum of 800 V spike was applied to the power supplies, and up to 100 V spike applied to temperature sensor lines. Under these relatively mild tests, no failures were noted due to power supply transients, but three units failed when subjected to transients on their temperature sensor lines. Mechanical backup systems were designed to provide essential life-support during critical conditions of extreme outside conditions and extreme animal densities. The design and installation of environmental control systems for (1) a gestation unit and (2) a broiler house was performed. An overview of the process, and difficulties noted, is presented. Both systems incorporated mechanical backups. 20 refs.

  17. Evaluation of thermal control coatings for use on solar dynamic radiators in low earth orbit

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.; Rodriguez, Elvin; Slemp, Wayne S.; Stoyack, Joseph E.

    1991-01-01

    Thermal control coatings with high thermal emittance and low solar absorptance are needed for Space Station Freedom (SSF) solar dynamic power module radiator (SDR) surfaces for efficient heat rejection. Additionally, these coatings must be durable to low earth orbital (LEO) environmental effects of atomic oxygen, ultraviolet radiation and deep thermal cycles which occur as a result of start-up and shut-down of the solar dynamic power system. Eleven candidate coatings were characterized for their solar absorptance and emittance before and after exposure to ultraviolet (UV) radiation (200 to 400 nm), vacuum UV (VUV) radiation (100 to 200 nm) and atomic oxygen. Results indicated that the most durable and best performing coatings were white paint thermal control coatings Z-93, zinc oxide pigment in potassium silicate binder, and YB-71, zinc orthotitanate pigment in potassium silicate binder. Optical micrographs of these materials exposed to the individual environmental effects of atomic oxygen and vacuum thermal cycling showed that no surface cracking occurred.

  18. Controlling the Lithiation-Induced Strain and Charging Rate in Nanowire Electrodes by Coating

    SciTech Connect

    Zhang, Li Q.; Liu, Xiao H.; Liu, Yang; Huang, Shan; Zhu, Ting; Gui, Liangjin; Mao, Scott X.; Ye, Zhi Zhen; Wang, Chong M.; Sullivan, J. P.; Huang, Jian Yu

    2011-05-04

    Lithiation-induced-strain (LIS) in electrode materials plagues the performance and lifetime of lithium ion batteries (LIBs). Controlling the LIS is one of the ultimate goals for making better LIBs. Here we report that by carbon or aluminum coating, the charging rate and LIS of individual SnO2 nanowire electrodes can be altered dramatically: namely the carbon or aluminum coated nanowires can be charged about 10 times faster than the non-coated nanowires, and the radial expansion of the coated nanowires was completely suppressed, resulting little or no mismatch strain at the reaction front, as evidenced by the lack of dislocations near the reaction front. The improved charging rate and the suppression of the radial expansion were attributed to the mechanical confinement of the coatings. These studies demonstrate an effective route to control the charging rate and LIS, enabling the design of better LIBs.

  19. Evaluation of thermal control coatings for use on solar dynamic radiators in low Earth orbit

    NASA Technical Reports Server (NTRS)

    Dever, Joyce A.; Rodriguez, Elvin; Slemp, Wayne S.; Stoyack, Joseph E.

    1991-01-01

    Thermal control coatings with high thermal emittance and low solar absorptance are needed for Space Station Freedom (SSF) solar dynamic power module radiator (SDR) surfaces for efficient heat rejection. Additionally, these coatings must be durable to low earth orbital (LEO) environmental effects of atomic oxygen, ultraviolet radiation and deep thermal cycles which occur as a result of start-up and shut-down of the solar dynamic power system. Eleven candidate coatings were characterized for their solar absorptance and emittance before and after exposure to ultraviolet (UV) radiation (200 to 400 nm), vacuum UV (VUV) radiation (100 to 200 nm) and atomic oxygen. Results indicated that the most durable and best performing coatings were white paint thermal control coatings Z-93, zinc oxide pigment in potassium silicate binder, and YB-71, zinc orthotitanate pigment in potassium silicate binder. Optical micrographs of these materials exposed to the individual environmental effects of atomic oxygen and vacuum thermal cycling showed that no surface cracking occurred.

  20. High-performance nanoscale composite coatings for boiler applications

    NASA Astrophysics Data System (ADS)

    Branagan, D. J.; Breitsameter, M.; Meacham, B. E.; Belashchenko, V.

    2005-06-01

    In this article, we will show how unconventional nanoscale composite coatings can be formed using conventional wire-arc thermal spray systems. The as-sprayed SHS7170 wire-arc coatings are found to develop an amorphous matrix structure containing starburst-shaped boride and carbide crystallites with sizes ranging from 60 to 140 nm. After heating to temperatures above the peak crystalline temperature (566 °C), a solid/state transformation occurs that results in the formation of an intimate three-phase matrix structure consisting of the same complex boride and carbide phases, along with α-iron interdispersed on a structural scale from 60 to 110 nm. The nanocomposite microstructure contains clean grain boundaries, which are found to be extremely stable and resist coarsening throughout the range of temperatures found in boilers. Additionally, the properties of the coating are presented including the bond strength, hardness, bend resistance, and impact resistance. The sprayability, forgiveness, and repairability of the SHS7170 wire-arc coatings are explained in detail, with an emphasis on field applicability in boiler environments. The performance of the SHS7170 coatings in boiler environments is measured via elevated temperature-erosion experiments conducted at 300, 450, and 600 °C using bed ash from an operating circulating fluidized-bed combustor boiler, and the results are compared with those for existing boiler coatings.

  1. Tests of the Performance of Coatings for Low Ice Adhesion

    NASA Technical Reports Server (NTRS)

    Anderson, David N.; Reich, Allen D.

    1997-01-01

    This paper reports studies of the performance of low-ice-adhesion coatings by NASA Lewis and BFGoodrich. Studies used impact ice accreted both in the NASA Lewis Icing Research Tunnel (IRT) and in the BFGoodrich Icing Wind Tunnel (IWT) and static ice in a BFGoodrich bench-top parallel-plate shear rig. Early tests at NASA Lewis involved simple qualitative evaluations of the ease of removing impact ice from a surface. Coated surfaces were compared with uncoated ones. Some of the coatings were tested again with static ice at BFGoodrich to obtain quantitative measurements. Later, methods to establish the adhesion force on surfaces subjected to impact ice were explored at Lewis. This paper describes the various test programs and the results of testing some of the coatings looked at over the past 5 years. None of the coatings were found to be truly ice-phobic; however, the most effective coatings were found to reduce the adhesion of ice to about 1/2 that of an uncoated aluminum sample.

  2. Polymer coating of carrier excipients modify aerosol performance of adhered drugs used in dry powder inhalation therapy.

    PubMed

    Traini, Daniela; Scalia, Santo; Adi, Handoko; Marangoni, Elisabetta; Young, Paul M

    2012-11-15

    The potential of excipient coating to enhance aerosol performance of micronized drugs in carrier excipient-drug blends, used in dry powder inhalers, was investigated. Both EC (ethyl cellulose) and PVP (polyvinylpyrrolidone) were used as coating agents. Carriers were prepared via sieve fractioning followed by spray drying, with and without polymer additive. Each uncoated and coated carrier salbutamol sulphate (SS) blended systems were evaluated for particle size, morphology, drug carrier adhesion and aerosolisation performance, after blending and storage for 24h. All carrier-based systems prepared had similar particle sizes and morphologies. The surface chemistries of the carriers were significantly different, as was drug-carrier adhesion and aerosolisation performance. Particle adhesion between SS and aerosol performance (fine particle fraction; FPF) followed the rank: PVP coated>un-coated>EC coated lactose. This rank order could be attributed to the surface energy measured by contact goniometry and related to the chemistry of lactose and each polymer. Storage did not significantly affect aerosol performance, however a rank increase in mean FPF value was observed for uncoated and EC coated lactose. Finally, the net electrostatic charge across the aerosol cloud indicated that the EC coated lactose transferred less charge to SS particles. The performance of each carrier system could be attributed to the carrier surface chemistry and, in general, by careful selection of the coating polymer, drug-carrier adhesion, electrostatic charge and aerosol performance could be controlled. PMID:22964399

  3. LDEF thermal control coatings post-flight analysis

    NASA Technical Reports Server (NTRS)

    Slemp, Wayne S.; Young, Philip R.

    1993-01-01

    The NASA Long Duration Exposure Facility (LDEF) provided a unique flight opportunity for conducting experiments in space and return of these experiments to Earth for laboratory evaluation. The results of one of these experiments, S0010, Exposure of Spacecraft Coatings, in which selected spacecraft thermal control coatings were exposed to the low-Earth orbital (LEO) environment on LDEF are reported. The objective of the experiment is to evaluate the response of thermal control coatings to LEO exposure, which includes atomic oxygen, ultraviolet and particulate radiation, meteoroid and debris, vacuum, and temperature cycling.

  4. Photocatalytic Degradation of Cell Membrane Coatings for Controlled Drug Release.

    PubMed

    Rao, Lang; Meng, Qian-Fang; Huang, Qinqin; Liu, Pei; Bu, Lin-Lin; Kondamareddy, Kiran Kumar; Guo, Shi-Shang; Liu, Wei; Zhao, Xing-Zhong

    2016-06-01

    Biomimetic cell-membrane-camouflaged particles with desirable features have been widely used for various biomedical applications. However, there are few reports on employing these particles for cancer drug delivery due to the failure of the membrane coatings to be efficiently degraded in the tumor microenvironment which hampers the drug release. In this work, core-shell SiO2 @TiO2 nanoparticles with enhanced photocatalytic activity are used for controlled degradation of surface erythrocyte membrane coatings. The antitumor drug docetaxel is encapsulated into nanocarriers to demonstrate the controlled drug release under ultraviolet irradiation, and the drug-loaded nanoparticles are further used for enhanced cancer cell therapy. Here, a simple but practical method for degradation of cell membrane coatings is presented, and a good feasibility of using cell membrane-coated nanocarriers for controlled drug delivery is demonstrated. PMID:27191802

  5. Coating Processes Boost Performance of Solar Cells

    NASA Technical Reports Server (NTRS)

    2012-01-01

    NASA currently has spacecraft orbiting Mercury (MESSENGER), imaging the asteroid Vesta (Dawn), roaming the red plains of Mars (the Opportunity rover), and providing a laboratory for humans to advance scientific research in space (the International Space Station, or ISS). The heart of the technology that powers those missions and many others can be held in the palm of your hand - the solar cell. Solar, or photovoltaic (PV), cells are what make up the panels and arrays that draw on the Sun s light to generate electricity for everything from the Hubble Space Telescope s imaging equipment to the life support systems for the ISS. To enable NASA spacecraft to utilize the Sun s energy for exploring destinations as distant as Jupiter, the Agency has invested significant research into improving solar cell design and efficiency. Glenn Research Center has been a national leader in advancing PV technology. The Center s Photovoltaic and Power Technologies Branch has conducted numerous experiments aimed at developing lighter, more efficient solar cells that are less expensive to manufacture. Initiatives like the Forward Technology Solar Cell Experiments I and II in which PV cells developed by NASA and private industry were mounted outside the ISS have tested how various solar technologies perform in the harsh conditions of space. While NASA seeks to improve solar cells for space applications, the results are returning to Earth to benefit the solar energy industry.

  6. Coating Soybean Seed with Oxamyl for Control of Heterodera glycines

    PubMed Central

    Townshend, J. L.

    1990-01-01

    Oxamyl coated on soybean (Glycine max (L.) Merr. cv. Elgin) seeds in solutions of 20, 40, 80, and 160 mg/ml had no serious deleterious effects on seedling emergence and growth when planted in sterile soil. Seedling emergence on day 3 was less than that of the uncoated control, but by day 7 emergence was equal to, or greater than, the control. Shoot and root growth from seed coated with oxamyl in 40 and 80 mg/ml solutions was greater than that of the control. In soil infested with soybean cyst nematode, Heterodera glycines, shoot weight of soybean plants from seeds coated with oxamyl in 80 mg/ml solution was 11 and 9% greater at weeks 3 and 7, respectively, than from uncoated seeds. Numbers of juveniles (J3 and J4) and adults of H. glycines observed on the roots of plants from oxamyl-coated seeds were 83, 42, and 49% less at weeks 3, 5, and 7, respectively, than numbers on the roots of the untreated control. Numbers of J2 extracted from the roots of plants from oxamyl-coated seeds were 75% less at weeks 5 and 7 than those extracted from roots of uncoated seeds. The numbers of J2 extracted from the soil planted to oxamyl-coated seeds were 51 and 33% less at weeks 5 and 7, respectively, than from soil planted to uncoated seed. PMID:19287713

  7. Performance of fuel failure detection system for coated particle fuels

    SciTech Connect

    Treada, H.; Ohkawa, H.; Ohlsu, H.; Wakayama, N.; Yoshida, H.

    1985-04-01

    An experimental system was developed for a study of fuel failure detection (FFD) method for coated particle fuels (CPF's) of a high-temperature gas-cooled reactor. Various performance of the FFD-system were examined using a CPF-irradiation rig in the Japan Material Testing Reactor. By experiments, it was made sure that the counting rates of fission products (FP's), released from the CPF's, change with the reactor-power and the fuel-temperature remarkably even during the normal reactor operation. Also, an ability of the selective detection of only short-life FP-nuclides was studied in relation to the travelling time of the sampling gas. The results showed that the contributions of the short-life FP-nuclides such as Kr-89 and Kr-90 are more than 80 percent to the total FP-counting rate at the shortest travelling time of 120 sec. It is concluded that the selective detection of only the short-life FP-nuclides can be realized by controlling the travelling time properly.

  8. Surface figure control for coated optics

    DOEpatents

    Ray-Chaudhuri, Avijit K.; Spence, Paul A.; Kanouff, Michael P.

    2001-01-01

    A pedestal optical substrate that simultaneously provides high substrate dynamic stiffness, provides low surface figure sensitivity to mechanical mounting hardware inputs, and constrains surface figure changes caused by optical coatings to be primarily spherical in nature. The pedestal optical substrate includes a disk-like optic or substrate section having a top surface that is coated, a disk-like base section that provides location at which the substrate can be mounted, and a connecting cylindrical section between the base and optics or substrate sections. The optic section has an optical section thickness.sup.2 /optical section diameter ratio of between about 5 to 10 mm, and a thickness variation between front and back surfaces of less than about 10%. The connecting cylindrical section may be attached via three spaced legs or members. However, the pedestal optical substrate can be manufactured from a solid piece of material to form a monolith, thus avoiding joints between the sections, or the disk-like base can be formed separately and connected to the connecting section. By way of example, the pedestal optical substrate may be utilized in the fabrication of optics for an extreme ultraviolet (EUV) lithography imaging system, or in any optical system requiring coated optics and substrates with reduced sensitivity to mechanical mounts.

  9. Control of Seed Coat Thickness and Permeability in Soybean 1

    PubMed Central

    Noodén, L. D.; Blakley, K. A.; Grzybowski, J. M.

    1985-01-01

    Although the seed coat, through its thickness and permeability, often regulates seed germination, very little is known about the control of its development. Using soybean (Glycine max [L.] Merrill) explants, podbearing cuttings in which defined solutions can be substituted for the roots, we have demonstrated that cytokinin and mineral nutrients moving through the xylem can control soybean seed coat development. Lack of cytokinin and minerals in the culture solution, causes a thicker, less permeable seed coat to develop. The seeds with thickened coats will imbibe water rapidly if scarified; furthermore, these scratched seeds also germinate and produce normal plants. Inasmuch as stress (e.g. drought) decreases mineral assimilation and cytokinin production by the roots, the resulting delay in germination could be an adaptive response to stress. PMID:16664447

  10. Fluoropolymer surface coatings to control droplets in microfluidic devices.

    PubMed

    Riche, Carson T; Zhang, Chuchu; Gupta, Malancha; Malmstadt, Noah

    2014-06-01

    We have demonstrated the application of low surface energy fluoropolymer coatings onto poly(dimethylsiloxane) (PDMS) microfluidic devices for droplet formation and extraction-induced merger of droplets. Initiated chemical vapor deposition (iCVD) was used to pattern fluoropolymer coatings within microchannels based on geometrical constraints. In a two-phase flow system, the range of accessible flow rates for droplet formation was greatly enhanced in the coated devices. The ability to controllably apply the coating only at the inlet facilitated a method for merging droplets. An organic spacer droplet was extracted from between a pair of aqueous droplets. The size of the organic droplet and the flow rate controlled the time to merge the aqueous droplets; the process of merging was independent of the droplet sizes. Extraction-induced droplet merging is a robust method for manipulating droplets that could be applied in translating multi-step reactions to microfluidic platforms. PMID:24722827

  11. A new class of high performance protective coatings for the rail industry based on siloxane technology

    SciTech Connect

    Hull, C.G.; Woods, J.J.

    1995-12-01

    A novel new class of protective coatings has been developed which is based on the hybridization of inorganic siloxane polymers with organic epoxy polymers. These coatings exhibit the corrosion resistance of an epoxy and weathering resistance superior to the best aliphatic polyurethane. As a result, traditional high performance 3-coat inorganic zinc/epoxy/polyurethane coatings can be replaced with 2-coat zinc/epoxy siloxane coatings with significant savings in applied cost.

  12. Environmentally Friendly Coating Technology for Autonomous Corrosion Control

    NASA Technical Reports Server (NTRS)

    Calle, Luz M.; Li, Wenyan; Buhrow, Jerry W.; Johnsey, Marissa N.; Jolley, Scott T.; Pearman, Benjamin P.; Zhang, Xuejun; Fitzpatrick, Lilliana; Gillis, Mathew; Blanton, Michael; Hanna, Joshua S.; Rawlins, James W.

    2016-01-01

    This work concerns the development of environmentally friendly encapsulation technology, specifically designed to incorporate corrosion indicators, inhibitors, and self-healing agents into a coating, in such a way that the delivery of the indicators and inhibitors is triggered by the corrosion process, and the delivery of self-healing agents is triggered by mechanical damage to the coating. Encapsulation of the active corrosion control ingredients allows the incorporation of desired autonomous corrosion control functions such as: early corrosion detection, hidden corrosion detection, corrosion inhibition, and self-healing of mechanical damage into a coating. The technology offers the versatility needed to include one or several corrosion control functions into the same coating.The development of the encapsulation technology has progressed from the initial proof-of-concept work, in which a corrosion indicator was encapsulated into an oil-core (hydrophobic) microcapsule and shown to be delivered autonomously, under simulated corrosion conditions, to a sophisticated portfolio of micro carriers (organic, inorganic, and hybrid) that can be used to deliver a wide range of active corrosion ingredients at a rate that can be adjusted to offer immediate as well as long-term corrosion control. The micro carriers have been incorporated into different coating formulas to test and optimize the autonomous corrosion detection, inhibition, and self-healing functions of the coatings. This paper provides an overview of progress made to date and highlights recent technical developments, such as improved corrosion detection sensitivity, inhibitor test results in various types of coatings, and highly effective self-healing coatings based on green chemistry.

  13. A Multifunctional Smart Coating for Autonomous Corrosion Control

    NASA Technical Reports Server (NTRS)

    Calle, Luz Marina; Buhrow, Jerry W.; Jolley, Scott T.

    2012-01-01

    Corrosion is a destructive process that often causes failure in metallic components and structures. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional, smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to control it. The multi-functionality of the coating is based on micro-encapsulation technology specifically designed for corrosion control applications. This design has, in addition to all the advantages of other existing microcapsules designs, the corrosion controlled release function that allows the delivery of corrosion indicators and inhibitors on demand only when and where needed. Corrosion indicators as well as corrosion inhibitors have been incorporated into microcapsules, blended into several paint systems, and tested for corrosion detection and protection efficacy. This

  14. Use of hydrophilic polymer coatings for control of electroosmosis and protein adsorption

    NASA Technical Reports Server (NTRS)

    Harris, J. Milton

    1987-01-01

    The purpose of this project was to examine the utility of polyethylene glycol (PEG) and dextran coatings for control of electroosmosis and protein adsorption; electroosmosis is an important, deleterious process affecting electrophoretic separations, and protein adsorption is a factor which needs to be controlled during protein crystal growth to avoid multiple nucleation sites. Performance of the project required use of X-ray photoelectron spectroscopy to refine previously developed synthetic methods. The results of this spectroscopic examination are reported. Measurements of electroosmotic mobility of charged particles in appropriately coated capillaries reveals that a new, one-step route to coating capillaries gives a surface in which electroosmosis is dramatically reduced. Similarly, both PEG and dextran coatings were shown by protein adsorption measurements to be highly effective at reducing protein adsorption on solid surfaces. These results should have impact on future low-g electrophoretic and protein crystal growth experiments.

  15. Post Irradiation Evaluation of Thermal Control Coatings and Solid Lubricants to Support Fission Surface Power Systems

    NASA Astrophysics Data System (ADS)

    Bowman, Cheryl L.; Jaworske, Donald A.; Stanford, Malcolm K.; Persinger, Justin A.; Khorsandi, Behrooz; Blue, Thomas E.

    2007-01-01

    The development of a nuclear power system for space missions, such as the Jupiter Icy Moons Orbiter or a lunar outpost, requires substantially more compact reactor design than conventional terrestrial systems. In order to minimize shielding requirements and hence system weight, the radiation tolerance of component materials within the power conversion and heat rejection systems must be defined. Two classes of coatings, thermal control paints and solid lubricants, were identified as material systems for which limited radiation hardness information was available. Screening studies were designed to explore candidate coatings under a predominately fast neutron spectrum. The Ohio State Research Reactor Facility staff performed irradiation in a well characterized, mixed energy spectrum and performed post irradiation analysis of representative coatings for thermal control and solid lubricant applications. Thermal control paints were evaluated for 1 MeV equivalent fluences from 1013 to 1015 n/cm2. No optical degradation was noted although some adhesive degradation was found at higher fluence levels. Solid lubricant coatings were evaluated for 1 MeV equivalent fluences from 1015 to 1016 n/cm2 with coating adhesion and flexibility used for post irradiation evaluation screening. The exposures studied did not lead to obvious property degradation indicating the coatings would have survived the radiation environment for the previously proposed Jupiter mission. The results are also applicable to space power development programs such as fission surface power for future lunar and Mars missions.

  16. Post Irradiation Evaluation of Thermal Control Coatings and Solid Lubricants to Support Fission Surface Power Systems

    NASA Technical Reports Server (NTRS)

    Bowman, Cheryl L.; Jaworske, Donald A.; Stanford, Malcolm K.; Persinger, Justin A.; Khorsandi, Behrooz; Blue, Thomas E.

    2007-01-01

    The development of a nuclear power system for space missions, such as the Jupiter Icy Moons Orbiter or a lunar outpost, requires substantially more compact reactor design than conventional terrestrial systems. In order to minimize shielding requirements and hence system weight, the radiation tolerance of component materials within the power conversion and heat rejection systems must be defined. Two classes of coatings, thermal control paints and solid lubricants, were identified as material systems for which limited radiation hardness information was available. Screening studies were designed to explore candidate coatings under a predominately fast neutron spectrum. The Ohio State Research Reactor Facility staff performed irradiation in a well characterized, mixed energy spectrum and performed post irradiation analysis of representative coatings for thermal control and solid lubricant applications. Thermal control paints were evaluated for 1 MeV equivalent fluences from 10(exp 13) to 10(exp 15) n per square centimeters. No optical degradation was noted although some adhesive degradation was found at higher fluence levels. Solid lubricant coatings were evaluated for 1 MeV equivalent fluences from 10(exp 15) to 10(exp 16) n per square centimeters with coating adhesion and flexibility used for post irradiation evaluation screening. The exposures studied did not lead to obvious property degradation indicating the coatings would have survived the radiation environment for the previously proposed Jupiter mission. The results are also applicable to space power development programs such as fission surface power for future lunar and Mars missions.

  17. Post Irradiation Evaluation of Thermal Control Coatings and Solid Lubricants to Support Fission Surface Power Systems

    SciTech Connect

    Bowman, Cheryl L.; Jaworske, Donald A.; Stanford, Malcolm K.; Persinger, Justin A.; Khorsandi, Behrooz; Blue, Thomas E.

    2007-01-30

    The development of a nuclear power system for space missions, such as the Jupiter Icy Moons Orbiter or a lunar outpost, requires substantially more compact reactor design than conventional terrestrial systems. In order to minimize shielding requirements and hence system weight, the radiation tolerance of component materials within the power conversion and heat rejection systems must be defined. Two classes of coatings, thermal control paints and solid lubricants, were identified as material systems for which limited radiation hardness information was available. Screening studies were designed to explore candidate coatings under a predominately fast neutron spectrum. The Ohio State Research Reactor Facility staff performed irradiation in a well characterized, mixed energy spectrum and performed post irradiation analysis of representative coatings for thermal control and solid lubricant applications. Thermal control paints were evaluated for 1 MeV equivalent fluences from 1013 to 1015 n/cm2. No optical degradation was noted although some adhesive degradation was found at higher fluence levels. Solid lubricant coatings were evaluated for 1 MeV equivalent fluences from 1015 to 1016 n/cm2 with coating adhesion and flexibility used for post irradiation evaluation screening. The exposures studied did not lead to obvious property degradation indicating the coatings would have survived the radiation environment for the previously proposed Jupiter mission. The results are also applicable to space power development programs such as fission surface power for future lunar and Mars missions.

  18. Development of silane-hydrolysate binder for UV-resistant thermal control coatings

    NASA Technical Reports Server (NTRS)

    Patterson, W. J.

    1981-01-01

    Detailed characterizaton and formulation studies were performed on a methyltriakoxysilane hydrolysate as a binder for thermal control coatings. The binder was optimized by varying hydrolysis temperature, time, catalyst type, and water concentration. The candidate coating formulations, based on this binder with TiO2 pigment, were optimized via a detailed series of sprayed test panels that included the parameters of binder/pigment ratio, ethanol content, pigment particle size, coating thickness and cure conditions. A typical optimized coating was prepared by acetic acid catalyzed hydrolysis of methyltriethoxysilane with 3.25 mol-equivalents of water over a 24 hour period at room temperature. The resulting hydrolysate was directly mixed with pre-milled TiO2 (12 grams pigment/26 grams binder) to yield a sprayable consistency. Panels were sprayed to result in a nominal cure coating thickness of 2 mils. Cure was affected by air drying for 24 hr at room temperature plus 72 hr at 150 F. These coatings are typically extremely tough and abrasion-resistant, with an absorptance (alpha) of 0.20 and emittance (e) of 0.89. No significant coating damage was observed in the mandrel bend test, even after exposure to thermal cycling from -160 to 160 F. Vacuum exposure of the coatings for 930 hours at 1 equivalent UV sun resulted in no visible degradation and no significant increase in absorptance.

  19. Antibacterial Performance of Alginic Acid Coating on Polyethylene Film

    PubMed Central

    Karbassi, Elika; Asadinezhad, Ahmad; Lehocký, Marian; Humpolíček, Petr; Vesel, Alenka; Novák, Igor; Sáha, Petr

    2014-01-01

    Alginic acid coated polyethylene films were examined in terms of surface properties and bacteriostatic performance against two most representative bacterial strains, that is, Escherichia coli and Staphylococcus aureus. Microwave plasma treatment followed by brush formation in vapor state from three distinguished precursors (allylalcohol, allylamine, hydroxyethyl methacrylate) was carried out to deposit alginic acid on the substrate. Surface analyses via various techniques established that alginic acid was immobilized onto the surface where grafting (brush) chemistry influenced the amount of alginic acid coated. Moreover, alginic acid was found to be capable of bacterial growth inhibition which itself was significantly affected by the brush type. The polyanionic character of alginic acid as a carbohydrate polymer was assumed to play the pivotal role in antibacterial activity. The cell wall composition of two bacterial strains along with the substrates physicochemical properties accounted for different levels of bacteriostatic performance. PMID:25196604

  20. Corrosion performance of zinc coated steel in seawater environment

    NASA Astrophysics Data System (ADS)

    Liu, Shuan; Zhao, Xia; Zhao, Haichao; Sun, Huyuan; Chen, Jianmin

    2016-05-01

    Considering the continuous exploitation of marine resources, it is very important to study the anticorrosion performance and durability of zinc coated streel (ZCS) because its increasing use as reinforcements in seawater. Tafel polarization curves and linear polarization curves combined with electrochemical impedance spectroscopy (EIS) were employed to evaluate the corrosion performance of ZCS at Qingdao test station during long-term immersion in seawater. The results indicated that the corrosion rate of the ZCS increased obviously with immersion time in seawater. The corrosion products that formed on the zinc coated steel were loose and porous, and were mainly composed of Zn5(OH)8Cl2, Zn5(OH)6(CO3)2, and ZnO. Pitting corrosion occurred on the steel surface in neutral seawater, and the rate of ZCS corrosion decreased with increasing pH.

  1. Improvement in Plasma Performance with Lithium Coatings in NSTX

    SciTech Connect

    Kaita, R; Ahn, J -W; Allain, J P; Bell, M G; Bell, R; Boedo, J; Bush, C; Mansfield, D; Menard, J; Mueller, D; Ono, M; Paul, S; Raman, R; Roquemore, A L; Ross, P W; Sabbagh, S; Schneider, H; Skinner, C H; Soukhanovskii, V; Stevenson, T; Stotler, D; Timberlake, J; Wampler, W R; Wilgen, J B

    2008-09-12

    Lithium as a plasma-facing material has attractive features, including a reduction in the recycling of hydrogenic species and the potential for withstanding high heat and neutron fluxes in fusion reactors. Dramatic effects on plasma performance with lithium-coated plasma-facing components (PFCOs) have been demonstrated on many fusion devices, including TFTR, [1] T-11M, [2] and FT-U. [3] Using a liquid-lithium-filled tray as a limiter, the CDX-U device achieved very significant enhancement in the confinement time of ohmically heated plasmas. [4] The recent NSTX experiments reported here have demonstrated, for the first time, significant and recurring benefits of lithium PFC coatings on divertor plasma performance in both L- and H- mode regimes heated by neutral beams.

  2. Improvement in Plasma Performance with Lithium Coatings in NSTX

    SciTech Connect

    Kaita, R

    2009-02-17

    Lithium as a plasma-facing material has attractive features, including a reduction in the recycling of hydrogenic species and the potential for withstanding high heat and neutron fluxes in fusion reactors. Dramatic effects on plasma performance with lithium-coated plasma-facing components (PFC's) have been demonstrated on many fusion devices, including TFTR, T-11M, and FT-U. Using a liquid-lithium-filled tray as a limiter, the CDX-U device achieved very significant enhancement in the confinement time of ohmically heated plasmas. The recent NSTX experiments reported here have demonstrated, for the first time, significant and recurring benefits of lithium PFC coatings on divertor plasma performance in both L- and H- mode regimes heated by neutral beams.

  3. Comparison study of different coatings on degradation performance and cell response of Mg-Sr alloy.

    PubMed

    Shangguan, Yongming; Sun, Lina; Wan, Peng; Tan, Lili; Wang, Chengyue; Fan, Xinmin; Qin, Ling; Yang, Ke

    2016-12-01

    To solve the problem of rapid degradation for magnesium-based implants, surface modification especially coating method is widely studied and showed the great potential for clinical application. However, as concerned to the further application and medical translation for biodegradable magnesium alloys, there are still lack of data and comparisons among different coatings on their degradation and biological properties. This work studied three commonly used coatings on Mg-Sr alloy, including micro-arc oxidation coating, electrodeposition coating and chemical conversion coating, and compared these coatings for requirements of favorable degradation and biological performances, how each of these coating systems has performed. Finally the mechanism for the discrepancy between these coatings is proposed. The results indicate that the micro-arc oxidation coating on Mg-Sr alloy exhibited the best corrosion resistance and cell response among these coatings, and is proved to be more suitable for the orthopedic application. PMID:27612693

  4. Space Environmental Effects on Thermal Control Coatings

    NASA Technical Reports Server (NTRS)

    OBrien, Susan K.; Workman, Gary L.

    1997-01-01

    The study of long term near ultra-violet (NUV) effects in a vacuum atmosphere, is a crucial element for space applications. NUV radiation causes significant changes in the reflectance of many coatings and types of materials. An ultra high vacuum NUV system was assembled in order to investigate various coatings and materials in this hostile environment. The vacuum is an ion pump that maintains a minimum vacuum in the mid 10(exp -9) range. The system has a base pressure of 10(exp -9) torr and this base pressure is maintained with the ion pump. The NUV exposure was maintained at 2-3 suns which allows accelerated NUV exposure without overheating the samples. The goal of this test was to maintain an intensity of 3.4 x 10(exp -2) Watts/cm(exp 2) which equals 2.9 NUV suns. An NUV sun is defined as 1.16 Watts/cm(exp 2) integrated over wavelength of 200-400 nanometers.

  5. Apparatus for and method of controlling sputter coating

    SciTech Connect

    Boys, R.

    1985-02-19

    The magnetic field of a magnetron sputter coating apparatus is controlled in response to measurements of plasma parameters to control deposition parameters, such as sputter deposition rate and material deposition thickness profile. From time to time the apparatus is standardized to change preset values for parameters of the plasma to manage the deposition parameters.

  6. Black coatings for stray light and thermal control applications

    NASA Astrophysics Data System (ADS)

    Moldosanov, Kamil A.; Kashirin, Victor A.; Skrynnikov, Alexander M.; Anisimova, Irina A.; Anisimov, Vladimir P.; Kobtsov, Gennady A.

    2001-11-01

    This report deals with comparison of the total hemispherical reflectances (THR), emissivities, and solar radiation absorption factors of coatings designed to reduce a stray light background and provide the thermal control both in space-based instruments and in land-based equipment. The THR measurement results are presented that have been carried out at 10 values of wavelengths within visible, near- ultraviolet, and near-infrared ranges (400 to 927 nm). The coatings being compared are as follows: chemically oxidized copper, coating on the basis of Al-N system, black-chromium coating, black bituminous paint, commercial black enamel used in solar converters, and plasmatron sputtered nichrome and constantan alloys. The chemically oxidized copper has been chosen as a material possessing high solar radiation absorption factor and low emissivity. Black-chromium coating is a widespread material for thermal control in space instruments. The black bituminous paint has been chosen as a possible cheap alternative solar absorber. Commercial black enamel served as a standard conventional coating used in some inexpensive solar converters. Nichrome and constantan have been also selected for investigations as the alloys having high specific resistivities, which promised that intensive electron scattering in skin layers of these alloys could take place, i.e., intensive transfer of energy and momentum received from the light wave to the lattice.

  7. Development of a thermal control coating for space suits

    NASA Technical Reports Server (NTRS)

    Squire, Bernadette; Webbon, Bruce

    1987-01-01

    Past space suits and the current Shuttle suit, which are constructed primarily from fabric, use the Integrated Thermal and Micrometeoroid Garment, which insulates the astronaut from his environment. The new generation of hard suits affords designers the opportunity to incorporate thermal control into the suit structure. Environmental influence on the suit temperature and heat flux can then be minimized with a high reflectance coating. Candidate coatings have been identified and ranked on the basis of thermophysical properties; wear, corrosion and atomic oxygen degradation resistance; and coating process and cost. Laboratory determination of properties, thermal cycling and wear resistance tests are underway to identify the optimum coating. A computer model is being developed to evaluate various environmental configurations. Preliminary results are presented here.

  8. Coating synthesis controlled by electron-beam heating

    NASA Astrophysics Data System (ADS)

    Gordienko, A. I.; Knyazeva, A. G.; Pobol, I. L.

    2016-07-01

    The methods of combined electron-beam treatment of parts made of steel with one- and two-layer coatings are studied experimentally. Ti-Ni, Ni-Al and Al-Ti systems were used as the examples in the experiments. The mathematical model is suggested for coating formation in the controlled regime of high temperature synthesis during high energy source motion along the preliminarily deposited layer of exothermic composition. The study takes into account the difference in thermophysical properties of the materials of coating and substrate, heat release from chemical reaction that leads to the coating properties formation and other factors. The realization of the synthesis depends on technological parameters. Various regimes of the treatment process are investigated numerically.

  9. Controlling film topography to form highly hydrophobic waterborne coatings.

    PubMed

    López, Ana B; de la Cal, José C; Asua, José M

    2016-08-17

    Coatings have a tremendous impact on economy as they reduce corrosion that has an estimated cost of 3% of the world's GDP. Hydrophobic coatings are particularly efficient for this purpose and the challenge is to produce cost effective and environmentally friendly, highly hydrophobic, cohesive and non-porous coatings applicable to large and irregular surfaces. This work shows that this goal can be achieved by forming wrinkles on the surface of waterborne coatings through fine-tuning of the film forming conditions. The proof of concept was demonstrated by using waterborne dispersions of copolymers of 1H,1H,2H,2H-perfluorodecyl acrylate and 2-ethylhexyl acrylate, and using the temperature and hardness of the copolymer as control variables during film formation. This allowed the formation of transparent films with a wrinkled surface that had a contact angle of 133°, which represents an increase of 20° with respect to the film cast under standard conditions. PMID:27476531

  10. Optical Property Evaluation of Next Generation Thermal Control Coatings

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Deshpande, Mukund S.; Pierson, Edward A.

    2010-01-01

    Next generation white thermal control coatings were developed via the Small Business Innovative Research program utilizing lithium silicate chemistry as a binder. Doping of the binder with additives yielded a powder that was plasma spray capable and that could be applied to light weight polymers and carbon-carbon composite surfaces. The plasma sprayed coating had acceptable beginning-of-life and end-of-live optical properties, as indicated by a successful 1.5 year exposure to the space environment in low Earth orbit. Recent studies also showed the coating to be durable to simulated space environments consisting of 1 keV and 10 keV electrons, 4.5 MeV electrons, and thermal cycling. Large scale deposition was demonstrated on a polymer matrix composite radiator panel, leading to the selection of the coating for use on the Gravity Recovery And Interior Laboratory (GRAIL) mission.

  11. Simulation of controllable permeation in PNIPAAm coated membranes

    NASA Astrophysics Data System (ADS)

    Ehrenhofer, Adrian; Wallmersperger, Thomas; Richter, Andreas

    2016-04-01

    Membranes separate fluid compartments and can comprise transport structures for selective permeation. In biology, channel proteins are specialized in their atomic structure to allow transport of specific compounds (selectivity). Conformational changes in protein structure allow the control of the permeation abilities by outer stimuli (gating). In polymeric membranes, the selectivity is due to electrostatic or size-exclusion. It can thus be controlled by size variation or electric charges. Controllable permeation can be useful to determine particle-size distributions in continuous flow, e.g. in microfluidics and biomedicine to gain cell diameter profiles in blood. The present approach uses patterned polyethylene terephthalate (PET) membranes with hydrogel surface coating for permeation control by size-exclusion. The thermosensitive hydrogel poly(N-isopropylacrylamide) (PNIPAAm) is structured with a cross-shaped pore geometry. A change in the temperature of the water flow through the membrane leads to a pore shape variation. The temperature dependent behavior of PNIPAAm can be numerically modeled with a temperature expansion model, where the swelling and deswelling is depicted by temperature dependent expansion coefficients. In the present study, the free swelling behavior was implemented to the Finite Element tool ABAQUS for the complex composite structure of the permeation control membrane. Experimental values of the geometry characteristics were derived from microscopy images with the tool Image J and compared to simulation results. Numerical simulations using the derived thermo-mechanical model for different pore geometries (circular, rectangle, cross and triangle) were performed. With this study, we show that the temperature expansion model with values from the free swelling behavior can be used to adequately predict the deformation behavior of the complex membrane system. The predictions can be used to optimize the behavior of the membrane pores and the overall

  12. Antimicrobial beeswax coated polylactide films with silver control release capacity.

    PubMed

    Martínez-Abad, Antonio; Lagarón, Jose Maria; Ocio, María Jose

    2014-03-17

    Although the application of silver based antimicrobial systems is a widespread technology, its implementation in areas such as food packaging is still challenging. The present paper describes the fabrication of poly(lactic acid) (PLA) coated with beeswax with controlled release properties for sustained antimicrobial performance. Release of silver ions from the polymers was monitored voltammetrically under various conditions (surface contact, immersion in various liquid media and at different pH values) throughout at least 7days. A higher release was noted with decreasing pH while surface release was much slower than the release when immersed in liquid medium. While uncoated films demonstrated a high burst release which in some instances implied surpassing some current migration restrictions (<0.05mg/kg food), the addition of a beeswax layer allowed a sustained release of the antimicrobial compound. Increasing the thickness of the beeswax layer resulted in an increase in the water barrier properties of the films while reducing the relatively constant values of sustained release. Antimicrobial performance was correlated with the release of silver ions, indicating threshold concentrations for biocide action of <6μg/L and 9-14μg/L for surface contact and in liquid media, respectively. Either by surface contact or by immersion in growth medium or vegetable soup, the coated films displayed a strong bactericidal effect against Salmonella enterica. The application of this functional barrier thus offers the possibility of tuning the release profiles of the films to suit a specific application and puts forth the possible suitability of these materials for food packaging or other migration sensitive applications. PMID:24448276

  13. Coronary Stent Materials and Coatings: A Technology and Performance Update.

    PubMed

    O'Brien, Barry; Zafar, Haroon; Ibrahim, Ahmad; Zafar, Junaid; Sharif, Faisal

    2016-02-01

    This paper reviews the current state of the art for coronary stent materials and surface coatings, with an emphasis on new technologies that followed on from first-generation bare metal and drug-eluting stents. These developments have been driven mainly by the need to improve long term outcomes, including late stent thrombosis. Biodegradable drug-eluting coatings aim to address the long term effects of residual durable polymer after drug elution; the SYNERGY, BioMatrix, and Nobori stents are all promising devices in this category, with minimal polymer through the use of abluminal coatings. Textured stent surfaces have been used to attached drug directly, without polymer; the Yukon Choice and BioFreedom stents have some promising data in this category, while a hydroxyapatite textured surface has had less success. The use of drug-filled reservoirs looked promising initially but the NEVO device has experienced both technical and commercial set-backs. However this approach may eventually make it to market if trials with the Drug-Filled Stent prove to be successful. Non-pharmacological coatings such as silicon carbide, carbon, and titanium-nitride-oxide are also proving to have potential to provide better performance than BMS, without some of the longer term issues associated with DES. In terms of biological coatings, the Genous stent which promotes attachment of endothelial progenitor cells has made good progress while gene-eluting stents still have some practical challenges to overcome. Perhaps the most advancement has been in the field of biodegradable stents. The BVS PLLA device is now seeing increasing clinical use in many complex indications while magnesium stents continue to make steady advancements. PMID:26139297

  14. Coated Porous Si for High Performance On-Chip Supercapacitors

    NASA Astrophysics Data System (ADS)

    Grigoras, K.; Keskinen, J.; Grönberg, L.; Ahopelto, J.; Prunnila, M.

    2014-11-01

    High performance porous Si based supercapacitor electrodes are demonstrated. High power density and stability is provided by ultra-thin TiN coating of the porous Si matrix. The TiN layer is deposited by atomic layer deposition (ALD), which provides sufficient conformality to reach the bottom of the high aspect ratio pores. Our porous Si supercapacitor devices exhibit almost ideal double layer capacitor characteristic with electrode volumetric capacitance of 7.3 F/cm3. Several orders of magnitude increase in power and energy density is obtained comparing to uncoated porous silicon electrodes. Good stability of devices is confirmed performing several thousands of charge/discharge cycles.

  15. High performance composites with active stiffness control.

    PubMed

    Tridech, Charnwit; Maples, Henry A; Robinson, Paul; Bismarck, Alexander

    2013-09-25

    High performance carbon fiber reinforced composites with controllable stiffness could revolutionize the use of composite materials in structural applications. Here we describe a structural material, which has a stiffness that can be actively controlled on demand. Such a material could have applications in morphing wings or deployable structures. A carbon fiber reinforced-epoxy composite is described that can undergo an 88% reduction in flexural stiffness at elevated temperatures and fully recover when cooled, with no discernible damage or loss in properties. Once the stiffness has been reduced, the required deformations can be achieved at much lower actuation forces. For this proof-of-concept study a thin polyacrylamide (PAAm) layer was electrocoated onto carbon fibers that were then embedded into an epoxy matrix via resin infusion. Heating the PAAm coating above its glass transition temperature caused it to soften and allowed the fibers to slide within the matrix. To produce the stiffness change the carbon fibers were used as resistance heating elements by passing a current through them. When the PAAm coating had softened, the ability of the interphase to transfer load to the fibers was significantly reduced, greatly lowering the flexural stiffness of the composite. By changing the moisture content in PAAm fiber coating, the temperature at which the PAAm softens and the composites undergo a reduction in stiffness can be tuned. PMID:23978266

  16. Controlled delivery of paclitaxel from stent coatings using novel styrene maleic anhydride copolymer formulations.

    PubMed

    Richard, Robert; Schwarz, Marlene; Chan, Ken; Teigen, Nikolai; Boden, Mark

    2009-08-01

    The controlled release of paclitaxel (PTx) from stent coatings comprising an elastomeric polymer blended with a styrene maleic anhydride (SMA) copolymer is described. The coated stents were characterized for morphology by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and for drug release using high-performance liquid chromatography (HPLC). Differential scanning calorimetry (DSC) was used to measure the extent of interaction between the PTx and polymers in the formulation. Coronary stents were coated with blends of poly(b-styrene-b-isobutylene-b-styrene) (SIBS) and SMA containing 7% or 14% maleic anhydride (MA) by weight. SEM examination of the stents showed that the coating did not crack or delaminate either before or after stent expansion. Examination of the coating surface via AFM after elution of the drug indicated that PTx resides primarily in the SMA phase and provided information about the mechanism of PTx release. The addition of SMA altered the release profile of PTx from the base elastomer coatings. In addition, the presence of the SMA enabled tunable release of PTx from the elastomeric stent coatings, while preserving mechanical properties. Thermal analysis reveled no shift in the glass transition temperatures for any of the polymers at all drug loadings studied, indicating that the PTx is not miscible with any component of the polymer blend. An in vivo evaluation indicated that biocompatibility and vascular response results for SMA/SIBS-coated stents (without PTx) are similar to results for SIBS-only-coated and bare stainless steel control stents when implanted in the non-injured coronary arteries of common swine for 30 and 90 days. PMID:18563805

  17. Radiation control coatings installed on rough-surfaced built-up roofs -- Initial results

    SciTech Connect

    Petrie, T.W.; Childs, P.W.; Christian, J.E.

    1998-01-01

    The authors have tracked the solar reflectance and thermal performance of small samples of various radiation control coatings on smooth surfaces for several years on a roof test facility in East Tennessee. The focus is on white coatings because of their potential to weather, causing the solar reflectance to decrease as the coatings age. Support of the federal New Technology Demonstration Program allowed them to extend the study to more samples on smooth surfaces and entire rough-surfaced roofs at a federal facility in the Panhandle of Florida. Two rough-surfaced, moderately well-insulated, low solar reflectance built-up roofs (BURs) were spray-coated with a latex-based product with ceramic beads added to improve solar reflectance. In the first three months after installation, the fresh BUR coatings showed a significant decrease in both the outside-surface temperature and the heat flux through the roof insulation. Average sunlit values were generated to exclude nighttime data, data on cloudy days, and data when the uncoated patch on one roof was more strongly shaded in mid-afternoon on sunny days. The average power demand during occupied periods for the first month with the coating for the building with the thermally massive roof deck was 13% less than during the previous month without the coating. For the other buildings with a lightweight roof deck but high internal loads, there were no clear average power savings due to the coating. The authors are continuing to monitor electricity use in these all-electric buildings to calibrate a model for the peak power and annual energy use of the buildings. Modeling results to be given at the end of the two year project will address the effect of roof R-value, geographic location, and solar reflectance, including the effect of weathering, on the performance of coated roofs. The calibrated models should allow one to segregate site-specific effects such as shading and large thermal mass.

  18. Smart microneedle coatings for controlled delivery and biomedical analysis.

    PubMed

    Khan, H; Mehta, P; Msallam, H; Armitage, D; Ahmad, Z

    2014-11-01

    The work presented demonstrates an unconventional approach in the preparation of smart microneedle (MN) coatings utilising electrohydrodynamic atomisation (EHDA) principles. Stainless steel (600-900 µm in height) MNs were coupled to a ground electrode (in the EHDA coating set-up) with the deposition distance and collecting methodology varied for an ethanol:methanol (50:50) vehicle system. The preparation of nano- and micrometre-scaled pharmaceutical coatings was achieved. Fluorescein dye (serving as potential drug, sensory materials or disease state markers) and polyvinylpyrrolidone (PVP, polymer matrix system) formed the remaining components of the coating formulation. Based on these excipients and by varying the coating process, particles (100 nm to 3 µm) and fibres (400 nm to 1 µm) were deposited directly on MNs in controlled and selectable fashion (flow rates variable ∼ 5-50 µL/min, applied voltage variable 6-19 kV). These demonstrated options for multiple targeting and analysis applications. The underlying EHDA process permits room temperature fabrication, controlled output and scale-up potential for emerging MN devices as drug systems or lab-chip testing devices. PMID:24892742

  19. Switchable surface coatings for control over protein adsorption

    NASA Astrophysics Data System (ADS)

    Cole, Martin A.; Jasieniak, Marek; Voelcker, Nicolas H.; Thissen, Helmut; Horn, Roger; Griesser, Hans J.

    2007-12-01

    Control over biomolecule interactions at interfaces is becoming an increasingly important goal for a range of scientific fields and is being intensively studied in areas of biotechnological, biomedical and materials science. Improvement in the control over materials and biomolecules is particularly important to applications such as arrays, biosensors, tissue engineering, drug delivery and 'lab on a chip' devices. Further development of these devices is expected to be achieved with thin coatings of stimuli responsive materials that can have their chemical properties 'switched' or tuned to stimulate a certain biological response such as adsorption/desorption of proteins. Switchable coatings show great potential for the realisation of spatial and temporal immobilisation of cells and biomolecules such as DNA and proteins. This study focuses on protein adsorption onto coatings of the thermosensitive polymer poly(N-isopropylacrylamide) (pNIPAM) which can exhibit low and high protein adsorption properties based on its temperature dependent conformation. At temperatures above its lower critical solution temperature (LCST) pNIPAM polymer chains are collapsed and protein adsorbing whilst below the LCST they are hydrated and protein repellent. Coatings of pNIPAM on silicon wafers were prepared by free radical polymerisation in the presence of surface bound polymerisable groups. Surface analysis and protein adsorption was carried out using X-ray photoelectron spectroscopy, time of flight secondary ion mass spectrometry and contact angle measurements. This study is expected to aid the development of stimuli-responsive coatings for biochips and biodevices.

  20. Anodisation with dynamic current control for tailored alumina coatings

    NASA Astrophysics Data System (ADS)

    Sieber, M.; Althöfer, I.; Höhlich, D.; Scharf, I.; Böttger, D.; Böttger, S.; Böttger, E.; Lampke, T.

    2016-03-01

    The anodic oxidation process is commonly used to refine the surface of aluminium and its alloys. Compared to the substrate, the alumina layers produced by anodising exhibit an increased hardness and chemical resistance. Thus, the corrosion and wear resistance are generally improved. The coatings are also electrically isolating and may serve decorative purposes. Applying a time-variant, dynamic electrical process control by pulse-current or current-steps is a promising approach to improve the coating properties, which is partially deployed in an industrial scale. In the present work, the influence of dynamic electrical process control on the coating properties is examined by means of a design of experiments (DOE). The effects of various electrolyte compositions and temperatures as well as processing time are considered with regard to coating thickness, hardness, wear resistance and the electrical energy consumption during the formation of the coatings. Information about the statistical significance of the effects of the parameters on the considered properties is obtained by an analysis of variance (ANOVA).

  1. Effect of back-side-coated electrodes on electrochemical performances of lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Lee, Yunju; Son, Bongki; Choi, Jaecheol; Kim, Jong Hun; Ryou, Myung-Hyun; Lee, Yong Min

    2015-02-01

    In order to investigate the effect of back-side coating of cathodes and anodes upon electrochemical performances of lithium-ion batteries (LIBs), four different pouch-type lithium cobalt oxide (LiCoO2, LCO)/graphite unit cells with different coating conditions are prepared and compared in a systematic manner. Their electrochemical performance, in terms of Coulombic efficiency, capacity realization, capacity retention ability, and rate capabilities, is investigated. From the results, we confirm an opposing relationship existing between back-side-coated cathodes and anodes, in that the coated cathodes provide improved cell performance, while the coated anodes impede it. This is attributed to the fact that, as is generally understood, cathodes act as noble lithium (Li) ion suppliers for LIBs, while anodes consume a large portion of Li ions to form surface layers during the first charging process. Furthermore, we also confirm that the magnitude of the back-side coating effect for LCO and graphite are somewhat different. The double-side-coated cathodes have a notable positive effect on cell performances in contrast to the negative effect seen with the double-side-coated anodes. As a result, unit cells employing double-side-coated cathodes with single-side-coated anodes show the best performance, followed by those based on double-side-coated cathodes with double-side-coated anodes rather than single-side-coated cathodes with single-side coated anodes.

  2. Results of the examination of LDEF polyurethane thermal control coatings

    NASA Technical Reports Server (NTRS)

    Golden, Johnny L.

    1994-01-01

    This report summarizes the condition of polyurethane thermal control coatings subjected to 69 months of low earth orbit (LEO) exposure on the Long Duration Exposure Facility (LDEF) mission. Specimens representing all environmental aspects obtainable by LDEF were analyzed. Widely varying changes in the thermo-optical and mechanical properties of these materials were observed, depending on atomic oxygen and ultraviolet radiation fluences. High atomic oxygen fluences, regardless of ultraviolet radiation exposure levels, resulted in near original optical properties for these coatings but with a degradation in their mechanical condition. A trend in solar absorptance increase with ultraviolet radiation fluence was observed. Contamination, though observed, exhibited minimal effects.

  3. Current technology for development of low solar absorptance/high emittance coatings. [spacecraft thermal control surface materials

    NASA Technical Reports Server (NTRS)

    Gilligan, J. E.; Harada, Y.; Gates, D. W.

    1974-01-01

    A comprehensive program to develop low solar absorptance/high emittance coatings, to be successful, must coordinate basic materials preparation, coatings technology, environmental simulation, production, and flight-test evaluation. The prime criteria for 'white' thermal-control coatings are low solar absorptance and, most importantly, solar-absorptance stability. Many variables affect the solar absorptance and its stability. These effects must be discerned and evaluated. The factors involved, however, are not entirely independent; accordingly, the present paper emphasizes the major variables, the relationships among them, and how important they are in improving the properties and performance of the coatings.

  4. Coatings in space environment. [for satellite thermal control

    NASA Technical Reports Server (NTRS)

    Triolo, J. J.; Heaney, J. B.; Hass, G.

    1978-01-01

    The behavior in space environment of evaporated Al uncoated and coated with reactively deposited silicon oxide (SiOx), electron beam evaporated SiO2 and Al2O3, and Al and Ag coated with double layers of Al2O3 + SiOx is compared with metallized Teflon and Kapton, anodized Al (Alzak), and white paints. Flight data from three calorimetric experiments and one reflectometer flown in different orbital environments are compared with laboratory test data. The results demonstrate that evaporated thin films are extremely versatile and stable coatings for space applications. Through the use of control samples studied in different laboratory tests and monitored for up to 12,000 hours of solar exposure in different orbits, a classification of orbital severity and an estimate of laboratory simulation accuracy is obtained.

  5. Formulation of electrically conductive thermal-control coatings

    NASA Technical Reports Server (NTRS)

    Shai, M. C.

    1978-01-01

    The development and formulation of electrically conductive thermal control coating was undertaken for use on the International Sun Earth Explorer spacecraft. The primary effort was to develop a coating with a bulk resistivity of less than 100,000 ohm/sqm, an optical absorptance of approximately 0.55, and a normal emittance of 0.90. The required stability in space called for a bulk resistivity of less than 100,000 ohm/sq m, an absorptance of less than 0.67, and a normal emittance of 0.90 after exposure to approximately 4 x 10 to the 16th proton/sq cm of solar-wind particles and 5300 equivalent sun-hours. These exposures represent 2 years of ISEE flight conditions. Both the unsuccessful formulation efforts and the successful use of oxide pigments fired at 1448 K are described. Problems relative to the reactivity of specific coating vehicles exposed to high humidity are discussed.

  6. Controlling Variable Emittance (MEMS) Coatings for Space Applications

    NASA Technical Reports Server (NTRS)

    Farrar, D.; Schneider, W.; Osiander, R.; Champion, J. L.; Darrin, A. G.; Douglas, Donya; Swanson, Ted D.

    2003-01-01

    Small spacecraft, including micro and nanosats, as they are envisioned for future missions, will require an alternative means to achieve thermal control due to their small power and mass budgets. One of the proposed alternatives is Variable Emittance (Vari-E) Coatings for spacecraft radiators. Space Technology-5 (ST-5) is a technology demonstration mission through NASA Goddard Space Flight Center (GSFC) that will utilize Vari-E Coatings. This mission involves a constellation of three (3) satellites in a highly elliptical orbit with a perigee altitude of approximately 200 kilometers and an apogee of approximately 38,000 kilometers. Such an environment will expose the spacecraft to a wide swing in the thermal and radiation environment of the earth's atmosphere. There are three (3) different technologies associated with this mission. The three technologies are electrophoretic, electrochromic, and Micro ElectroMechanical Systems (MEMS). The ultimate goal is to make use of Van-E coatings, in order to achieve various levels of thermal control. The focus of this paper is to highlight the Vari-E Coating MEMS instrument, with an emphasis on the Electronic Control Unit responsible for operating the MEMS device. The Test & Evaluation approach, along with the results, is specific for application on ST-5, yet the information provides a guideline for future experiments and/or thermal applications on the exterior structure of a spacecraft.

  7. Use of microcapsules as controlled release devices for coatings.

    PubMed

    Andersson Trojer, Markus; Nordstierna, Lars; Bergek, Jonatan; Blanck, Hans; Holmberg, Krister; Nydén, Magnus

    2015-08-01

    Biofouling of surfaces is a considerable problem in many industrial sectors and for the public community in general. The problem is usually approached by the use of functional coatings and most of such antifouling coatings rely on the effect of biocides. However, a substantial drawback is the poor control over the release of the biocide as well as its degradation in the paint. Encapsulation of the biocides in microcapsules is a promising approach that may overcome some of the problems associated with the more traditional ways of incorporating the antifouling agent into the formulation. In this review, we summarize more than a decade of microcapsule research from our lab as well as from other groups working on this topic. Focus will be on two coacervation-based encapsulation techniques; the internal phase separation method and the double emulsion method, which together enable the encapsulation of a broad spectrum of biocides with different physicochemical properties. The release of the biocide from core-shell particles and from encapsulated biocides in coatings is treated in detail. The release behaviour is interpreted in terms of the physicochemical properties of the core-shell particle and the coating matrix. In addition, special attention is given to the experimental release methodology and the implementation of proper diffusion models to describe the release. At the end of the review examples of antifouling properties of some coatings against common biofoulers are presented. PMID:25441449

  8. Boron nitride nanosheet coatings with controllable water repellency.

    PubMed

    Pakdel, Amir; Zhi, Chunyi; Bando, Yoshio; Nakayama, Tomonobu; Golberg, Dmitri

    2011-08-23

    The growth, structure, and properties of two-dimensional boron nitride (BN) nanostructures synthesized by a thermal chemical vapor deposition method have been systematically investigated. Most of the BN nanosheets (BNNSs) were less than 5 nm in thickness, and their purity was confirmed by X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, electron energy loss spectroscopy, and Raman spectroscopy. The effects of the process variables on the morphology and roughness of the coatings were studied using atomic force microscopy and scanning electron microscopy. A smooth BN coating was obtained at 900 °C, while compact BNNS coatings composed of partially vertically aligned nanosheets could be achieved at 1000 °C and higher temperatures. These nanosheets were mostly separated and exhibited high surface area especially at higher synthesis temperatures. The nonwetting properties of the BNNS coatings were independent of the water pH and were examined by contact angle goniometry. The present results enable a convenient growth of pure BNNS coatings with controllable levels of water repellency, ranging from partial hydrophilicity to superhydrophobicity with contact angles exceeding 150°. PMID:21766852

  9. Robotic weld overlay coatings for erosion control

    SciTech Connect

    Levin, B.F.; Dupont, J.N.; Marder, A.R.

    1993-04-18

    Twelve weld overlay hardfacing alloys have been selected for preliminary erosion testing based on a literature review These alloys have been separated into three major groups: (1) Cobalt containing alloys, (2) Nickel-base alloys, (3) Iron base alloys. These alloys are being applied to carbon steel substrates and will undergo preliminary erosion testing to identify candidates weld overlay alloys for erosion control in CFB boilers. The candidate alloys selected from the preliminary erosion tests will then undergo more detailed evaluations in future research.

  10. Electrically conductive, black thermal control coatings for spacecraft application. I - Silicate matrix formulation

    NASA Technical Reports Server (NTRS)

    Bauer, J. L.; Odonnell, T. P.; Hribar, V. F.

    1986-01-01

    The formulation of the graphite silicate paints MH-11 and MH-11Z, which will serve as electrically conductive, heat-resistant thermal control coatings for the Galileo spacecraft's 400 Newton engine plume shield, 10 Newton thruster plume shields, and external shunt radiators, is described, and performance results for these paints are reported. The MH-11 is produced by combining a certain grade of graphite powder with a silicate base to produce a black, inorganic, electrically conductive, room temperature cure thermal control paint having high temperature capability. Zinc oxide is added to the MH-11 formulation to produce the blister resistant painta MH-11Z. The mechanical, chemical, thermal, optical, and radiation characteristics of the coatings are reported. The formulation, mixing, application, and surface preparation of the substrates are described, and a method of determining the electrical resistance of the coatings is demonstrated.

  11. Further Analysis of Thermal Control Coatings on MISSE for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Kenny, Mike; McNulty, Robert; Finckenor, Miria

    2009-01-01

    Many different passive thermal control materials were flown as part of the Materials on International Space Station Experiment. Engineers and scientists at the Marshall Space Flight Center have analyzed a number of these materials, including Z93P zinc oxide/potassium silicate coating, YB-71P zinc orthotitanate/potassium silicate coating, NZOT, which is a low-cost alternative to YB-71P, several electrically conductive/static dissipative thermal control coatings, as well as black coatings for part marking and automated rendezvous and capture. These were exposed to the low Earth orbital environment of atomic oxygen, ultraviolet radiation, thermal cycling, and hard vacuum, though atomic oxygen exposure was very limited for some samples. Results from the one-year exposure of MISSE-3 and MISSE-4 are compared to the four-year exposure of MISSE-1 and MISSE-2. Solar absorptance, infrared emittance, and mass measurements indicate the durability of these materials to withstand the space environment. The effect of contamination from an active space station on the performance of white thermal control coatings is discussed.

  12. Weld overlay coatings for erosion control

    SciTech Connect

    Levin, B.; DuPont, J.N.; Marder, A.R.

    1993-03-03

    A literature review was made. In spite of similarities between abrasive wear and solid particle erosion, weld overlay hardfacing alloys that exhibit high abrasion resistance may not necessarily have good erosion resistance. The performance of weld overlay hardfacing alloys in erosive environments has not been studied in detail. It is believed that primary-solidified hard phases such as carbides and intermetallic compounds have a strong influence on erosion resistance of weld overlay hardfacing alloys. However, relationships between size, shape, and volume fraction of hard phases in a hardfacing alloys and erosion resistance were not established. Almost all hardfacing alloys can be separated into two major groups based upon chemical compositions of the primary solidified hard phases: (a) carbide hardening alloys (Co-base/carbide, WC-Co and some Fe base superalloys); and (b) intermetallic hardening alloys (Ni-base alloys, austenitic steels, iron-aluminides).

  13. In vitro performance of ceramic coatings obtained by high velocity oxy-fuel spray.

    PubMed

    Melero, H; Garcia-Giralt, N; Fernández, J; Díez-Pérez, A; Guilemany, J M

    2014-01-01

    Hydroxyapatite coatings obtained by plasma-spraying have been used for many years to improve biological performance of bone implants, but several studies have drawn attention to the problems arising from high temperatures and the lack of mechanical properties. In this study, plasma-spraying is substituted by high velocity oxy-fuel (HVOF) spray, with lower temperatures reached, and TiO2 is added in low amounts to hydroxyapatite in order to improve the mechanical properties. Four conditions have been tested to evaluate which are those with better biological properties. Viability and proliferation tests, as well as differentiation assays and morphology observation, are performed with human osteoblast cultures onto the studied coatings. The hydroxyapatite-TiO2 coatings maintain good cell viability and proliferation, especially the cases with higher amorphous phase amount and specific surface, and promote excellent differentiation, with a higher ALP amount for these cases than for polystyrene controls. Observation by SEM corroborates this excellent behaviour. In conclusion, these coatings are a good alternative to those used industrially, and an interesting issue would be improving biological behaviour of the worst cases, which in turn show the better mechanical properties. PMID:25201392

  14. Performance measures for multiprocessor controllers

    NASA Technical Reports Server (NTRS)

    Krishna, C. M.; Shin, K. G.

    1982-01-01

    Performance measures to characterize fault tolerant multiprocessors used in the control of critical processes are considered. Our performance indices are based on controller response time. By relating this to the needs of the application, we have been able to derive indices that faithfully reflect the performance of the multiprocessor in the context of the application, that permit the objective comparison of rival computer systems, and that can either be definitively estimated or objectively measured. An example of a controller in an idealized satellite application is provided.

  15. 49 CFR 195.561 - When must I inspect pipe coating used for external corrosion control?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false When must I inspect pipe coating used for external... inspect pipe coating used for external corrosion control? (a) You must inspect all external pipe coating... repair any coating damage discovered....

  16. 49 CFR 195.559 - What coating material may I use for external corrosion control?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false What coating material may I use for external...) PIPELINE SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Corrosion Control § 195.559 What coating material may I use for external corrosion control? Coating material for external corrosion control...

  17. Microtribological Performance of Metal-doped Molybdenum Disulfide Coatings

    NASA Astrophysics Data System (ADS)

    Stoyanov, Pantcho

    2011-07-01

    The mechanical and tribological properties of pure MoS2, pure Au, Au-MoS2 and Ti-MoS2 coatings were evaluated and examined at a microscopic scale. The metal doped MoS2 coatings had varying metal content, 5-10at% for Ti and 10-90% for Au. Reciprocating sliding wear tests were performed with a range of initial Hertzian contact pressures from 0.41 to 3.5 GPa and in air at two humidity levels (i.e. "low" being 3-5%RH and "high" being 30-40%RH). Titanium and gold were chosen for this study as metal additives due to their positive influence on the mechanical properties of the coating. The friction and wear behavior at the micro-scale were directly compared to tribological properties at the macro-scale, which were performed using an in situ tribometer. Reciprocating micro- and macro- wear tests were performed with spherical diamond tip (with 10 and 50 mum radii) and a sapphire tip (with a radius of 3.175 mm), respectively. The range of initial Hertzian contact pressures for macro-scale (i.e. between 0.41GPa and 1.2GPa) overlapped with that for micro-scale. However, the initial Hertzian contact diameters (2*a) were very different (i.e. 0.8-2.3 mum for micro-scale and 60-180 mum for macro-scale). It was observed that the small addition of Ti or Au to MoS2 improved the microtribological properties (i.e. lower friction and less wear) compared to pure MoS2 coatings. The improved microtribological properties with metal additions were attributed to an increase in the mechanical properties, decrease in adhesion, and a decrease in the interfacial shear strength. In terms of the different length scales, lower steady state friction was observed for macrotribology compared to microtribology. The higher friction at the micro- scale was explained by the greater adhesion effects and additional velocity accommodation modes (e.g. microplowing or plowing). The microplowing or plowing at the microscopic scale was attributed to the tip roughness and the inability to sustain a stable

  18. Contamination control in hybrid microelectronic modules. Part 3: Specifications for coating material and process controls

    NASA Technical Reports Server (NTRS)

    Himmel, R. P.

    1975-01-01

    Resin systems for coating hybrids prior to hermetic sealing are described. The resin systems are a flexible silicone junction resin system and a flexible cycloaliphatic epoxy resin system. The coatings are intended for application to the hybrid after all the chips have been assembled and wire bonded, but prior to hermetic sealing of the package. The purpose of the coating is to control particulate contamination by immobilizing particles and by passivating the hybrid. Recommended process controls for the purpose of minimizing contamination in hybrid microcircuit packages are given. Emphasis is placed on those critical hybrid processing steps in which contamination is most likely to occur.

  19. Ballistic performance of polyurea-coated armor grade ceramic tiles

    NASA Astrophysics Data System (ADS)

    Samiee, Ahsan; Isaacs, Jon; Nemat-Nasser, Sia

    2010-04-01

    The use of ceramics as energy absorbents has been studied by many researchers and some improvements in the ballistic performance of ceramic tiles have been made by coating them with different classes of materials (e.g. E-glass/epoxy, carbon-fiber/epoxy, etc.). Using ceramics for energy absorbing applications leads to a significant weight reduction of the system. Therefore, any modification to the ceramic configuration in the system which leads to more energy absorption with the same or less areal density is significant. On the other hand, polyurea has been proved to be an excellent energy dissipating agent in many applications. Inspired by this, we are studying the effect of coating ceramics with polyurea and other materials, on the energy absorption and ballistic performance of the resulting ceramic-based composites. In this study, we investigate the effect of polyurea on ballistic efficiency of ceramic tiles. To this end, we have performed a set of penetration tests on polyurea-ceramic composites. In our experiments, a high velocity projectile is propelled to impact and perforate the ceramic-polyurea composite. The velocity and mass of the projectile are measured before and after the penetration. The change in the kinetic energy of the projectile is evaluated and compared for different polyurea-ceramic configurations (e.g., polyurea on front face, polyurea on back face, polyurea between two ceramic tiles, etc.). The experimental results suggest that polyurea is not as effective as other restraining materials such as E-glass/epoxy and carbon-fiber/epoxy.

  20. Analytical performance characteristics of nanoelectrospray emitters as a function of conductive coating.

    PubMed

    Smith, Douglas R; Moy, Marie A; Dolan, Anthony R; Wood, Troy D

    2006-04-01

    As miniaturization of electrospray continues to become more prevalent in the mass spectrometry arsenal, numerous types of conductive coatings have been developed with miniaturized electrospray emitters. Different conductive coatings have different properties that may lead to differences in analytical performance. This paper investigates and compares the analytical properties of a series of applied conductive coatings for low-flow electrospray ionization developed in this laboratory vs. commercially-available types. Evaporated graphite is thoroughly compared with commercially available polyaniline (PANI) coated emitters and metal coated emitters. Each set of emitters was investigated to determine various performance characteristics, including susceptibility to electrical discharge in both positive and negative ionization modes, as well as emitter reproducibility and generation of a standard curve to determine each emitter coating's limit of detection and limit of quantitation. Furthermore, evaporated graphite and polyaniline coated fused silica capillaries were investigated to determine which coating is more stable over long-term analyses and during electrical discharge. PMID:16568172

  1. Development of coatings to control electroosmosis in zero gravity electrophoresis

    NASA Technical Reports Server (NTRS)

    Krupnick, A. C.

    1974-01-01

    A major problem confronting the operation of free fluid electrophoresis in zero gravity is the control of electrokinetic phenomena and, in particular, electroosmosis. Due to the severity of counter flow, as a result of electroosmosis, the electrical potential developed at the surface of shear must be maintained at near, or as close to, zero millivolts as possible. Based upon this investigation, it has been found that the amount of bound water or the degree of hydroxylation plays a major role in the control of this phenomena. Of necessity, factors, such as adhesion, biocompatibility, protein adsorption, and insolubility were considered in this investigation because of the long buffer-coating exposure times required by present space operations. Based upon tests employing microcapillary electrophoresis, it has been found that gamma amino propyl trihydroxysilane produced a coating which provides the lowest potential (minus 3.86 mv) at the surface of shear between the stationary and mobile layers. This coating has been soaked in both borate and saline buffers, up to three months, in a pH range of 6.5 to 10 without deleterious effects or a change in its ability to control electrokinetic effects.

  2. Generation and control of wide area, homogenous atmospheric pressure discharges for industrial coating applications.

    NASA Astrophysics Data System (ADS)

    Hynes, Alan; Walter, Castagna; Carr, Kieran; O'Shea, Sean; Herbert, Tony

    2004-09-01

    Dow Corning Plasma Solutions use diffuse atmospheric pressure plasma technology combined with a unique precursor delivery system for a new coatings approach: Atmospheric Pressure Plasma Liquid Deposition. Operating at atmospheric pressure and ambient temperature this process allows the use of a wide range of liquid precursors delivering high chemical functionality onto flexible substrates. Patented APPLD equipment enables plasma deposition onto wide area substrates up to 1.6m width in true reel-to-reel conditions at industrial line speeds up to 30m/min. Substrates can be either electrically insulating or conducting. Recent engineering developments addressing issues in electrode design, liquid delivery and gas retention and distribution, have significantly enhanced the stability and homogeneity of the plasma chemistry and coating performance. The process is controlled through monitoring and control of key plasma chemistry and process parameters. The process hardware and process control package will be described in detail with particular emphasis on plasma chemistry and process control tools.

  3. Optimum Me-DLC coatings and hard coatings for tribological performance[Diamond-Like Carbon

    SciTech Connect

    Su, Y.L.; Kao, W.H.

    2000-02-01

    In this study, hard coatings (TiN, TiCN, CrN, and CrCN) and Me-DLC coatings (Ti{sub x%}-C:H and Cr{sub x%}-C:H) were deposited on tungsten carbide (WC) substrate by multiarc physical vapor deposition (MAPVD) and unbalanced magnetron (UBM) sputtering, respectively. Counterbodies of the AISI 1045 steel cylinder and the AA7075T65l aluminum cylinder were used in the cylinder-on-disk, line-contact wear mode under dry condition; a counterbody of the AISI 51200 steel ball was used in the ball-on-disk, point-contact wear mode, under both dry and lubricated conditions. All wear tests were conducted with a reciprocating machine. After the tests, the most suitable coating for various counterbodies and test environments was selected. For the coating/1045 steel cylinder, the Ti{sub 10%}-C:H coating possesses excellent tribological characteristics. For the coating/7075T651 aluminum cylinder, hard coatings display excellent wear resistance. For the coating/steel ball, CrCN and CrN coatings display very little wear under both dry and lubricated conditions. On TiN and TiCN coatings, special wear mechanisms of material transfer, adhesion wear, and fatigue fracture occurred during initial tests under kerosene lubrication.

  4. Nanoparticle-coated separators for lithium-ion batteries with advanced electrochemical performance.

    PubMed

    Fang, Jason; Kelarakis, Antonios; Lin, Yueh-Wei; Kang, Chi-Yun; Yang, Ming-Huan; Cheng, Cheng-Liang; Wang, Yue; Giannelis, Emmanuel P; Tsai, Li-Duan

    2011-08-28

    We report a simple, scalable approach to improve the interfacial characteristics and, thereby, the performance of commonly used polyolefin based battery separators. The nanoparticle-coated separators are synthesized by first plasma treating the membrane in oxygen to create surface anchoring groups followed by immersion into a dispersion of positively charged SiO(2) nanoparticles. The process leads to nanoparticles electrostatically adsorbed not only onto the exterior of the surface but also inside the pores of the membrane. The thickness and depth of the coatings can be fine-tuned by controlling the ζ-potential of the nanoparticles. The membranes show improved wetting to common battery electrolytes such as propylene carbonate. Cells based on the nanoparticle-coated membranes are operable even in a simple mixture of EC/PC. In contrast, an identical cell based on the pristine, untreated membrane fails to be charged even after addition of a surfactant to improve electrolyte wetting. When evaluated in a Li-ion cell using an EC/PC/DEC/VC electrolyte mixture, the nanoparticle-coated separator retains 92% of its charge capacity after 100 cycles compared to 80 and 77% for the plasma only treated and pristine membrane, respectively. PMID:21731963

  5. Tribological performance of hybrid filtered arc-magnetron coatings - Part I: Coating deposition process and basic coating properties characterization

    SciTech Connect

    Gorokhovsky, Vladimir; Bowman, C.; Gannon, Paul E.; VanVorous, D.; Voevodin, A. A.; Rutkowski, A.; Muratore, C.; Smith, Richard J.; Kayani, Asghar N.; Gelles, David S.; Shutthanandan, V.; Trusov, B. G.

    2006-12-04

    Aircraft propulsion applications require low-friction and wear resistant surfaces that operate under high contact loads in severe environments. Recent research on supertough and low friction nanocomposite coatings produced with hybrid plasma deposition processes was demonstrated to have a high potential for such demanding applications. However, industrially scalable hybrid plasma technologies are needed for their commercial realization. The Large area Filtered Arc Deposition (LAFAD) process provides atomically smooth coatings at high deposition rates over large surface areas. The LAFAD technology allows functionally graded, multilayer, super-lattice and nanocomposite architectures of multi-elemental coatings via electro-magnetic mixing of two plasma flows composed of different metal ion vapors. Further advancement can be realized through a combinatorial process using a hybrid filtered arc-magnetron deposition system. In the present study, multilayer and nanostructured TiCrCN/TiCr +TiBC composite cermet coatings were deposited by the hybrid filtered arc-magnetron process. Filtered plasma streams from arc evaporated Ti and Cr targets, and two unbalanced magnetron sputtered B4C targets, were directed to the substrates in the presence of reactive gases. A multiphase nanocomposite coating architecture was designed to provide the optimal combination of corrosion and wear resistance of advanced steels (Pyrowear 675) used in aerospace bearing and gear applications. Coatings were characterized using SEM/EDS, XPS and RBS for morphology and chemistry, XRD and TEM for structural analyses, wafer curvature and nanoindentation for stress and mechanical properties, and Rockwell and scratch indentions for adhesion. Coating properties were evaluated for a variety of coating architectures. Thermodynamic modeling was used for estimation of phase composition of the top TiBC coating segment. Correlations between coating chemistry, structure and mechanical properties are discussed.

  6. Coatings.

    ERIC Educational Resources Information Center

    Anderson, Dennis G.

    1989-01-01

    This review covers analytical techniques applicable to the examination of coatings, raw materials, and substrates upon which coatings are placed. Techniques include chemical and electrochemical methods, chromatography, spectroscopy, thermal analysis, microscopy, and miscellaneous techniques. (MVL)

  7. Improving turbine engine compressor performance retention through airfoil coatings

    NASA Technical Reports Server (NTRS)

    Friedrich, L. A.

    1981-01-01

    In order to evaluate the potential effectiveness of coatings in limiting erosive damage to compressor airfoils, an effort was initiated to evaluate candidate coatings for substrate alloys typically used in commercial engine high compressor blades. Laboratory and rig erosion testing of plasma deposited and diffusion coatings described in this paper have shown the potential of a two to four fold improvement in erosion life. The selective application of these coatings to approximately the outer third of the airfoil avoids coating the fatigue critical region of the blade, thus providing erosion resistance potentially without compromising the fatigue strength of the blade. Both the plasma and the diffusion coatings also offer the advantage of low initial cost and a multi-source production base.

  8. 49 CFR 195.557 - Which pipelines must have coating for external corrosion control?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Which pipelines must have coating for external... must have coating for external corrosion control? Except bottoms of aboveground breakout tanks, each buried or submerged pipeline must have an external coating for external corrosion control if the...

  9. Surface control and cryogenic durability of transparent CNT coatings on dip-coated glass substrates.

    PubMed

    Wang, Zuo-Jia; Kwon, Dong-Jun; Gu, Ga-Young; Devries, K Lawrence; Park, Joung-Man

    2012-11-15

    Transparent carbon nanotube (CNT) coatings were deposited on boro-silicate glass substrates by dip-coating. Ultraviolet-visible (UV) spectra, surface resistance measurement, and the wettability tests were used to investigate the optical transmittance and electrical properties of these CNT coatings. The changes in electrical and optical properties of these coatings were observed to be functions of the number of dip-coating cycles. The surface resistance of the CNT coated substrates decreased dramatically as the number of dip-coatings was increased, whereas the increases in the CNT layer thickness beyond that for the first dipping cycle had little effect on the transparent-properties. Static contact angle measurements proved to be an effective means for evaluating the surface morphology of CNT coatings. The interfacial durability of the CNT coatings on a glass substrate was much better than that of ITO coatings over the temperature range from -150°C to +150°C. PMID:22918050

  10. Improved atomic force microscopy cantilever performance by partial reflective coating.

    PubMed

    Schumacher, Zeno; Miyahara, Yoichi; Aeschimann, Laure; Grütter, Peter

    2015-01-01

    Optical beam deflection systems are widely used in cantilever based atomic force microscopy (AFM). Most commercial cantilevers have a reflective metal coating on the detector side to increase the reflectivity in order to achieve a high signal on the photodiode. Although the reflective coating is usually much thinner than the cantilever, it can still significantly contribute to the damping of the cantilever, leading to a lower mechanical quality factor (Q-factor). In dynamic mode operation in high vacuum, a cantilever with a high Q-factor is desired in order to achieve a lower minimal detectable force. The reflective coating can also increase the low-frequency force noise. In contact mode and force spectroscopy, a cantilever with minimal low-frequency force noise is desirable. We present a study on cantilevers with a partial reflective coating on the detector side. For this study, soft (≈0.01 N/m) and stiff (≈28 N/m) rectangular cantilevers were used with a custom partial coating at the tip end of the cantilever. The Q-factor, the detection and the force noise of fully coated, partially coated and uncoated cantilevers are compared and force distance curves are shown. Our results show an improvement in low-frequency force noise and increased Q-factor for the partially coated cantilevers compared to fully coated ones while maintaining the same reflectivity, therefore making it possible to combine the best of both worlds. PMID:26199849

  11. Preparation, Characterization and Performance of CVR Coatings for PBR Fuels

    NASA Astrophysics Data System (ADS)

    Adams, J. W.; Barletta, R. E.; Vanier, P. E.; Dowell, M. B.; Lennartz, J. W.

    1994-07-01

    As a part of the US Space Nuclear Thermal Propulsion Program, a process to deposit refractory carbide coatings using a fluidized bed chemical vapor reaction (CVR) process has been developed. Several types of coating have been applied to the graphite substrate which served as a surrogate fuel kernel. The coatings include NbC in various thicknesses and a bilayer coating consisting of NbC and TaC with an intermediate layer of pyrolytic graphite(PG). They were applied to a surrogate fuel kernel consisting of a PG-coated, graphite particle. The particles were characterized prior to test for coating thickness, grain size, stoichiometry (NbC only), free carbon and surface area. The initial screening tests for these coatings consisted of heating in flowing hot hydrogen at one atmosphere. The carbon loss from these particles was measured as a function of time. Exposure temperatures ranging from 2500 to 3000 K were used and samples were exposed for up to 14 minutes in a cyclical fashion, cooling to room temperature between exposures. Microscopic examination of the coatings after exposure was conducted. The rate of weight loss from these particles can be characterized as a simple Arrhenius process. These rates are compared to that from other tests of coated materials under similar conditions.

  12. Process and performance optimization of bottom antireflective coatings: II

    NASA Astrophysics Data System (ADS)

    Ding, Shuji; Sagan, John P.; Shan, Jianhui; Gonzalez, Eleazar; Dixit, Sunit S.; Liu, Ying; Khanna, Dinesh N.

    1999-06-01

    The newly developed AZ BARLi II coating material is a photoresist solvent-based bottom antireflective coating (BARC) for i-line lithographic application. The coating material has good compatibility with common edge bead removal solvents such as ethyl lactate, PGME, or PGMEA mixed with ethyl lactate or PGME. To evaluate the BARC material, its chemical compatibility with common EBR solvents has been tested by several analytical techniques including liquid particle counts and surface defect studies. Both top and bottom EBR dispense processes have been investigated and optimized. Improvements on edge roughness, visual cleanliness, and the BARC coating buildup at the edge will be discussed in this paper.

  13. Development of space stable thermal control coatings for use on large space vehicles

    NASA Technical Reports Server (NTRS)

    Gilligan, J. E.

    1972-01-01

    A reserach project to develop space stable thermal control coatings for large surfaces is discussed. Four major tasks are considered: (1) pigment development, (2) binder development, (3) environmental effects evaluations, and (4) general coatings investigations.

  14. Control of flux pinning in MOD YBCO coated conductor.

    SciTech Connect

    Zhang, W.; Huang, Y.; Li, X.; Kodenkandath, T.; Rupich, M. W.; Schoop, U.; Verebelyi, D. T.; Thieme, C. L. H.; Siegal, E.; Holesinger, T. G.; Maiorov, B.; Civale, L.; Miller, D. J.; Maroni, V. A.; Li, J.; Martin, P. M.; Specht, E. D.; Goyal, A.; Paranthaman, M. P.; American Superconductor Corp.; LANL; ORNL

    2007-06-01

    NTwo different types of defect structures have been identified to be responsible for the enhanced pinning in metal organic deposited YBCO films. Rare earth additions result in the formation of nanodots in the YBCO matrix, which form uncorrelated pinning centers, increasing pinning in all magnetic field orientations. 124-type intergrowths, which form as laminar structures parallel to the ab-plane, are responsible for the large current enhancement when the magnetic field is oriented in the ab-plane. TEM studies showed that the intergrowths emanate from cuprous containing secondary phase particles, whose density is partially controlled by the rare earth doping level. Critical process parameters have been identified to control this phase formation, and therefore, control the f 24 intergrowth formation. This work has shown that through process control and proper conductor design, either by adjusting the composition or by multiple coatings of different functional layers, the desired angular dependence can be achieved.

  15. Controlling the lithiation-induced strain and charging rate in nanowire electrodes by coating.

    PubMed

    Zhang, Li Qiang; Liu, Xiao Hua; Liu, Yang; Huang, Shan; Zhu, Ting; Gui, Liangjin; Mao, Scott X; Ye, Zhi Zhen; Wang, Chong Min; Sullivan, John P; Huang, Jian Yu

    2011-06-28

    The advanced battery system is critically important for a wide range of applications, from portable electronics to electric vehicles. Lithium ion batteries (LIBs) are presently the best performing ones, but they cannot meet requirements for more demanding applications due to limitations in capacity, charging rate, and cyclability. One leading cause of those limitations is the lithiation-induced strain (LIS) in electrodes that can result in high stress, fracture, and capacity loss. Here we report that, by utilizing the coating strategy, both the charging rate and LIS of SnO(2) nanowire electrodes can be altered dramatically. The SnO(2) nanowires coated with carbon, aluminum, or copper can be charged about 10 times faster than the noncoated ones. Intriguingly, the radial expansion of the coated nanowires was completely suppressed, resulting in enormously reduced tensile stress at the reaction front, as evidenced by the lack of formation of dislocations. These improvements are attributed to the effective electronic conduction and mechanical confinement of the coatings. Our work demonstrates that nanoengineering the coating enables the simultaneous control of electrical and mechanical behaviors of electrodes, pointing to a promising route for building better LIBs. PMID:21542642

  16. Evaluation of commercially supplied silver coated Teflon for spacecraft temperature control usage

    NASA Technical Reports Server (NTRS)

    Heaney, J. B.

    1974-01-01

    A series of tests are described which were performed to evaluate the acceptability of a commercially supplied silver backed teflon thermal control coating relative to teflon previously coated at GSFC. Optical measurements made on numerous samples indicate that the commercial material possesses an average solar absorptance of 0.085, an emittance of 0.76 and an average alpha/epsilon equal to 0.112, all of which are equivalent to the GSFC coated teflon. The emittance of the protective inconel backing was found to be 0.037. The coating is shown to have good adhesion at the Ag-teflon interface and exposure to UV irradiation uncovered no coating irregularities. Temperature cycling over the range -135 C to +200 C produced crazing in the evaporated Ag layer as expected but no delamination was observed. The suitability of Mystik no. 7366 and 3M no. 467 adhesives as bonding agents for the metallized polymer is demonstrated. Various problems associated with production reproducibility and selection of a proper bonding process are discussed.

  17. Quality control of thermal sprayed coatings with an optoelectric sensor

    SciTech Connect

    Rothe, H.; Brandt, O.; Kasper, A.

    1995-12-31

    This paper reports on the development of a fully optoelectronic optical sensor that has been used for investigations concerning quality control of the high velocity oxygen fuel (HVOF) flame spraying process. The authors focused on the following parameters: WoC with Co, CoCr, Ni at T < 500 C, and Cr{sub 3}C{sub 2} with Ni-Cr, Ni at T < 900 C. Until recently, there was no non-destructive testing (NDT) approach for flame spraying available, which is a major drawback for many critical applications, like in the aerospace industry. For instance, while cooling down after spraying, cracks in the coatings may occur caused by strain. Furthermore, edges may cause similar damage to the coating. The idea was to provide the flame spraying industry with a measurement technology that is applicable in the workshop, has a contactless principle of operation and is fast compared to the commonly used metallography or scanning electron microscopy. The approach is designed for use close to the process, i.e. coating morphology was not the focus of the investigations. On the contrary, they tried to extract quality related information from surface microtopography which can be obtained in a non-destructive and affordable manner. Main points covered in this paper are theoretical considerations, the operational principles and construction of the sensor head, and quantitative metrology of surface damage such as variations in rms-roughness and cracks.

  18. Measurement of the nonmagnetic coating thickness of core-shell magnetic nanoparticles by controlled magnetization magnetic force microscopy

    NASA Astrophysics Data System (ADS)

    Angeloni, L.; Passeri, D.; Scaramuzzo, F. A.; Di Iorio, D.; Barteri, M.; Mantovani, D.; Rossi, M.

    2016-06-01

    Magnetic nanoparticles (MNPs) represent an interesting tool for several biomedical applications. In order to improve the dispersion stability, the biocompatibility and bio-functionality, MNPs need to be coated with non-magnetic films. The optimization of these systems requires the deep characterization not only of the magnetic core, but also of the coating features. Beside the chemical and physical properties of the coating, its thickness is another important property which can influence the size, the shape and the overall magnetic behavior of the NPs system. In this work we propose a possible method to measure the thickness of the non-magnetic coating of core-shell MNPs through the use of controlled magnetization-magnetic force microscopy (CM-MFM). A preliminary study on the applicability of the proposed method has been performed on Fe3O4 NPs coated with a Cu film.

  19. ACCESS: Detector Control and Performance

    NASA Astrophysics Data System (ADS)

    Morris, Matthew J.; Kaiser, M.; McCandliss, S. R.; Rauscher, B. J.; Kimble, R. A.; Kruk, J. W.; Wright, E. L.; Bohlin, R.; Kurucz, R. L.; Riess, A. G.; Pelton, R.; Deustua, S. E.; Dixon, W. V.; Sahnow, D. J.; Mott, D. B.; Wen, Y.; Benford, D. J.; Gardner, J. P.; Feldman, P. D.; Moos, H. W.; Lampton, M.; Perlmutter, S.; Woodgate, B. E.

    2014-01-01

    ACCESS, Absolute Color Calibration Experiment for Standard Stars, is a series of rocket-borne sub-orbital missions and ground-based experiments that will enable improvements in the precision of the astrophysical flux scale through the transfer of absolute laboratory detector standards from the National Institute of Standards and Technology (NIST) to a network of stellar standards with a calibration accuracy of 1% and a spectral resolving power of 500 across the 0.35 to 1.7 micron bandpass (companion poster, Kaiser et al.). The flight detector and detector spare have been selected and integrated with their electronics and flight mount. The controller electronics have been flight qualified. Vibration testing to launch loads and thermal vacuum testing of the detector, mount, and housing have been successfully performed. Further improvements to the flight controller housing have been made. A cryogenic ground test system has been built. Dark current and read noise tests have been performed, yielding results consistent with the initial characterization tests of the detector performed by Goddard Space Flight Center’s Detector Characterization Lab (DCL). Detector control software has been developed and implemented for ground testing. Performance and integration of the detector and controller with the flight software will be presented. NASA APRA sounding rocket grant NNX08AI65G supports this work.

  20. New Approach to Ceramic/Metal-Polymer Multilayered Coatings for High Performance Dry Sliding Applications

    NASA Astrophysics Data System (ADS)

    Rempp, A.; Killinger, A.; Gadow, R.

    2012-06-01

    The combination of thermally sprayed hard coatings with a polymer based top coat leads to multilayered coating systems with tailored functionalities concerning wear resistance, friction, adhesion, wettability or specific electrical properties. The basic concept is to combine the mechanical properties of the hard base coating with the tribological or chemical abilities of the polymer top coat suitable for the respective application. This paper gives an overview of different types of recently developed multilayer coatings and their application in power transmission under dry sliding conditions. State of the art coatings for dry sliding applications in power transmission are mostly based on thin film coatings like diamond-like carbon or solid lubricants, e.g. MoS2. A new approach is the combination of thin film coatings with combined multilayer coatings. To evaluate the capability of these tribological systems, a multi-stage investigation has been carried out. In the first stage the performance of the sliding lacquers and surface topography of the steel substrate has been evaluated. In the following stage thermally sprayed hard coatings were tested in combination with different sliding lacquers. Wear resistance and friction coefficients of combined coatings were determined using a twin disc test-bed.

  1. Method of Producing Controlled Thermal Expansion Coat for Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Brindley, William J. (Inventor); Miller, Robert A. (Inventor); Aikin, Beverly J. M. (Inventor)

    2000-01-01

    An improved thermal barrier coating and method for producing and applying such is disclosed herein. The thermal barrier coatings includes a high temperature substrate, a first bond coat layer applied to the substrate of MCrAlX and a second bond coat layer of MCrAlX with particles of a particulate dispersed throughout the MCrAlX and the preferred particulate is Al2O3. The particles of the particulate dispersed throughout the second bond coat layer preferably have a diameter of less then the height of the peaks of the second bond coat layer or a diameter of less than 5 micron. The method of producing the second bond coat layer may either include the steps of mechanical alloying of particles throughout the second bond coat layer, attrition milling the particles of the particulate throughout the second bond coat layer, or using electrophoresis to disperse the particles throughout the second bond coat layer. In the preferred embodiment of the invention the first bond coat layer is applied to the substrate. and then the second bond coat layer is thermally sprayed onto the first bond coat layer. Further, in a preferred embodiment of the invention a ceramic insulating layer covers the second bond coat layer.

  2. High performance bilateral telerobot control.

    PubMed

    Kline-Schoder, Robert; Finger, William; Hogan, Neville

    2002-01-01

    Telerobotic systems are used when the environment that requires manipulation is not easily accessible to humans, as in space, remote, hazardous, or microscopic applications or to extend the capabilities of an operator by scaling motions and forces. The Creare control algorithm and software is an enabling technology that makes possible guaranteed stability and high performance for force-feedback telerobots. We have developed the necessary theory, structure, and software design required to implement high performance telerobot systems with time delay. This includes controllers for the master and slave manipulators, the manipulator servo levels, the communication link, and impedance shaping modules. We verified the performance using both bench top hardware as well as a commercial microsurgery system. PMID:15458092

  3. Induction plasma calcining of pigment particles for thermal control coatings

    NASA Technical Reports Server (NTRS)

    Farley, E. P.

    1971-01-01

    Induction plasma heating techniques were studied for calcining zinc orthotitanate particles for use in thermal control coatings. Previous studies indicated that the optimum calcining temperature is between 1400 and 1750 C. An intermediate temperature (1670 C) was chosen as a reference point for running a temperature series at the reference point and 220 C on both sides. The effect of varying chamber temperature on the reflectance spectra, before and after vacuum UV irradiation, is presented. The correlation between Zn2Ti04 paramagnetic resonance activity and its susceptibility to vacuum UV damage is discussed.

  4. Advanced Low Conductivity Thermal Barrier Coatings: Performance and Future Directions (Invited paper)

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    2008-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and performance will be emphasized. Advanced thermal barrier coatings have been developed using a multi-component defect clustering approach, and shown to have improved thermal stability and lower conductivity. The coating systems have been demonstrated for high temperature combustor applications. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the toughened thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion, impact and high heat-flux damage mechanisms of the thermal barrier coatings will also be described.

  5. Performance Evaluation and Modeling of Erosion Resistant Turbine Engine Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Miller, Robert A.; Zhu, Dongming; Kuczmarski, Maria

    2008-01-01

    The erosion resistant turbine thermal barrier coating system is critical to the rotorcraft engine performance and durability. The objective of this work was to determine erosion resistance of advanced thermal barrier coating systems under simulated engine erosion and thermal gradient environments, thus validating a new thermal barrier coating turbine blade technology for future rotorcraft applications. A high velocity burner rig based erosion test approach was established and a new series of rare earth oxide- and TiO2/Ta2O5- alloyed, ZrO2-based low conductivity thermal barrier coatings were designed and processed. The low conductivity thermal barrier coating systems demonstrated significant improvements in the erosion resistance. A comprehensive model based on accumulated strain damage low cycle fatigue is formulated for blade erosion life prediction. The work is currently aiming at the simulated engine erosion testing of advanced thermal barrier coated turbine blades to establish and validate the coating life prediction models.

  6. Controlling gas diffusion layer oxidation by homogeneous hydrophobic coating for polymer electrolyte fuel cells

    NASA Astrophysics Data System (ADS)

    Hiramitsu, Yusuke; Sato, Hitoshi; Kobayashi, Kenji; Hori, Michio

    Reduced production costs and enhanced durability are necessary for practical application of polymer electrolyte fuel cells. There has been a great deal of concern about degradation of the gas diffusion layer located outside the membrane electrode assembly. However, very few studies have been carried out on the degradation process, and no suitable methods for improving the durability of the cell have been found. In this work, the influence on the cell performance and factors involved in the degradation of the gas diffusion layer has been clarified through power generation tests. Long-term power generation tests on single cells for 6000 h were carried out under high humidity conditions with homogeneous and inhomogeneous hydrophobic coating gas diffusion layers. The results showed that the increase in the diffusion overvoltage from the gas diffusion layer could be controlled by the use of a homogeneous coating. Post-analyses indicated that this occurred by controlling oxidation of the carbon fiber.

  7. Advanced Antireflection Coatings for High-Performance Solar Energy Applications

    NASA Technical Reports Server (NTRS)

    Pan, Noren

    2015-01-01

    Phase II objectives: Develop and refine antireflection coatings incorporating lanthanum titanate as an intermediate refractive index material; Investigate wet/dry thermal oxidation of aluminum containing semiconductor compounds as a means of forming a more transparent window layer with equal or better optical properties than its unoxidized form; Develop a fabrication process that allows integration of the oxidized window layer and maintains the necessary electrical properties for contacting the solar cell; Conduct an experimental demonstration of the best candidates for improved antireflection coatings.

  8. Development of coatings to control electroosmosis in zero gravity electrophoresis

    NASA Technical Reports Server (NTRS)

    Krupnick, A. C.

    1974-01-01

    A major problem confronting the operation of free fluid electrophoresis in zero gravity is the control of electrokinetic phenomena and, in particular, electroosmosis. Due to the severity of counter flow as a result of electroosmosis, the electrical potential developed at the surface of shear must be maintained at near, or as close, to zero millivolts as possible. Based upon this investigation, it has been found that the amount of bound water or the degree of hydroxylation plays a major role in the control of this phenomenon. Based upon tests employing microcapillary electrophoresis, it has been found that gamma amino propyl trihydroxysilane produced a coating which provides the lowest potential (about 3.86 mV) at the surface of shear between the stationary and mobile layers.

  9. Radiation control coatings installed on federal buildings at Tyndall Air Force Base. Volume 2: Long-term monitoring and modeling

    SciTech Connect

    Petrie, T.W.; Childs, P.W.

    1998-06-01

    The US Department of Energy`s (DOE`s) Federal Energy Management Program (FEMP) supports efforts to reduce energy use and associated expenses in the federal sector. One such effort, the New Technology Demonstration Program (NTDP), seeks to evaluate new energy-saving US technologies and secure their more timely adoption by the US government. Through a partnership with a federal site, the utility serving the site, a manufacturer of an energy-related technology, and other organizations associated with these interests, DOE can evaluate a new technology. The results of the program give federal agency decision makers more hands-on information with which to validate a decision to utilize a new technology in their facilities. This is the second volume of a two-volume report that describes the effects of radiation control coatings installed on federal buildings at Tyndall Air Force Base (AFB) in Florida by ThermShield International. ORNL`s Buildings Technology Center (BTC) was assigned the responsibility for gathering, analyzing, and reporting on the data to describe the effects of the coatings. The first volume described the monitoring plan and its implementation, the results of pre-coating monitoring, the coating installation, results from fresh coatings compared to pre-coating results, and a plan to decommission the monitoring equipment. This second volume updates and completes the presentation of data to compare performance of fresh coatings with weathered coatings.

  10. Properties of conductive coatings for thermal control mirrors and solar cell covers

    NASA Technical Reports Server (NTRS)

    Joslin, D. E.; Kan, H. K. A.

    1975-01-01

    Conductive transparent coatings applied to the dielectric surfaces of a spacecraft offer the possibility of distributing charge uniformly over the entire spacecraft surface. Optical and electrical measurements of such a coating as a function of temperature are described. These results are used in considering the impact of a conductive coating on the absorptance of thermal control mirrors and on the transmittance of solar cell cover glass, which can be improved by the application of an antireflection coating.

  11. Fluorescence of thermal control coatings on S0069 and A0114

    NASA Technical Reports Server (NTRS)

    Zwiener, James M.; Mell, Richard J.; Peters, Palmer N.; Wilkes, Donald R.; Miller, Edgar R.; Gregory, John C.

    1992-01-01

    Many of the thermal control surfaces exposed to the space environment during the 5.8 year LDEF mission experienced changes in fluorescence. All of the thermal control coatings flown on LDEF experiments S0069 and A0114 were characterized for fluorescence under ambient conditions. Some of the black coatings, having protective overcoats, appear bright yellow under ultraviolet exposure. Urethane based coatings exhibited emission spectra shifts toward longer wavelengths in the visible range. Zinc oxide pigment based coatings experienced a quenching of fluorescence, while zinc orthotitanate pigment based and other ceramic type coatings had no measurable fluorescence.

  12. Correlating Coating Characteristics with the Performance of Drug-Coated Balloons – A Comparative In Vitro Investigation of Own Established Hydrogel- and Ionic Liquid-Based Coating Matrices

    PubMed Central

    Kaule, Sebastian; Minrath, Ingo; Stein, Florian; Kragl, Udo; Schmidt, Wolfram; Schmitz, Klaus-Peter; Sternberg, Katrin; Petersen, Svea

    2015-01-01

    Drug-coated balloons (DCB), which have emerged as a therapeutic alternative to drug-eluting stents in percutaneous cardiovascular intervention, are well described with regard to clinical efficacy and safety within a number of clinical studies. In vitro studies elucidating the correlation between coating additive and DCB performance are however rare but considered important for the understanding of DCB requirements and the improvement of established DCB. In this regard, we examined three different DCB-systems, which were developed in former studies based on the ionic liquid cetylpyridinium salicylate, the body-own hydrogel hyaluronic acid and the pharmaceutically well-established hydrogel polyvinylpyrrolidone, considering coating morphology, coating thickness, drug-loss, drug-transfer to the vessel wall, residual drug-concentration on the balloon surface and entire drug-load during simulated use in an in vitro vessel model. Moreover, we investigated particle release of the different DCB during simulated use and determined the influence of the three coatings on the mechanical behavior of the balloon catheter. We could show that coating characteristics can be indeed correlated with the performance of DCB. For instance, paclitaxel incorporation in the matrix can reduce the drug wash-off and benefit a high drug transfer. Additionally, a thin coating with a smooth surface and high but delayed solubility can reduce drug wash-off and decrease particle burden. As a result, we suggest that it is very important to characterize DCB in terms of mentioned properties in vitro in addition to their clinical efficacy in order to better understand their function and provide more data for the clinicians to improve the tool of DCB in coronary angioplasty. PMID:25734818

  13. Thermo-Mechanical Analysis of Coated Particle Fuel Experiencing a Fast Control Rod Ejection Transient

    SciTech Connect

    Ortensi, J.; Brian Boer; Abderrafi M. Ougouag

    2010-10-01

    A rapid increase of the temperature and the mechanical stress is expected in TRISO coated particle fuel that experiences a fast Total Control Rod Ejection (CRE) transient event. During this event the reactor power in the pebble bed core increases significantly for a short time interval. The power is deposited instantly and locally in the fuel kernel. This could result in a rapid increase of the pressure in the buffer layer of the coated fuel particle and, consequently, in an increase of the coating stresses. These stresses determine the mechanical failure probability of the coatings, which serve as the containment of radioactive fission products in the Pebble Bed Reactor (PBR). A new calculation procedure has been implemented at the Idaho National Laboratory (INL), which analyzes the transient fuel performance behavior of TRISO fuel particles in PBRs. This early capability can easily be extended to prismatic designs, given the availability of neutronic and thermal-fluid solvers. The full-core coupled neutronic and thermal-fluid analysis has been modeled with CYNOD-THERMIX. The temperature fields for the fuel kernel and the particle coatings, as well as the gas pressures in the buffer layer, are calculated with the THETRIS module explicitly during the transient calculation. Results from this module are part of the feedback loop within the neutronic-thermal fluid iterations performed for each time step. The temperature and internal pressure values for each pebble type in each region of the core are then input to the PArticle STress Analysis (PASTA) code, which determines the particle coating stresses and the fraction of failed particles. This paper presents an investigation of a Total Control Rod Ejection (TCRE) incident in the 400 MWth Pebble Bed Modular reactor design using the above described calculation procedure. The transient corresponds to a reactivity insertion of $3 (~2000 pcm) reaching 35 times the nominal power in 0.5 seconds. For each position in the core

  14. Corrosion protection performance of porous strontium hydroxyapatite coating on polypyrrole coated 316L stainless steel.

    PubMed

    Gopi, D; Ramya, S; Rajeswari, D; Kavitha, L

    2013-07-01

    Polypyrrole/strontium hydroxyapatite bilayer coatings were achieved on 316L stainless steel (316L SS) by the electropolymerisation of pyrrole from sodium salicylate solution followed by the electrodeposition of porous strontium hydroxyapatite. The formation and the morphology of the bilayer coatings were characterised by Fourier transform infrared spectroscopy (FT-IR) and high resolution scanning electron microscopy (HRSEM), respectively. The corrosion resistance of the coated 316L SS specimens was investigated in Ringer's solution by electrochemical techniques and the results were substantiated with inductively coupled plasma atomic emission spectrometry (ICP-AES). The passive film underneath the polypyrrole layer is effective in protecting 316L SS against corrosion in Ringer's solution. Moreover, we believe that the top porous strontium hydroxyapatite layer can provide potential bioactivity to the 316L SS. PMID:23475060

  15. Osmium coated diffraction grating in the Space Shuttle environment - Performance

    NASA Technical Reports Server (NTRS)

    Torr, M. R.

    1985-01-01

    Samples coated with osmium were flown on the early Shuttle test flights, and on the return of these samples, the osmium coating was found to have disappeared, evidently due to the oxidation of the material in the atomic oxygen atmosphere. An instrument flown on the Spacelab 1 mission comprised an array of five spectrometers covering the extreme ultraviolet (EUV) to near-IR wavelengths. The EUV spectrometer contained an osmium-coated reflective grating located fairly deep within the instruments. Here, results of an assessment of the reflectivity and stability of the osmium surface over the course of the ten-day mission are reported. It is concluded that the osmium reflective coating remained stable relative to the spectrometer coated with MgF2 over the course of the mission. In addition, the ratio of sensitivity of these two spectrometers did not change in any major way from the time of the laboratory calibration until the time of flight two years later. Any changes are within the 50-percent calibration uncertainty.

  16. Fabrication and performance of silver coated copper powder

    NASA Astrophysics Data System (ADS)

    Cao, Xiao Guo; Zhang, Hai Yan

    2012-08-01

    Electroless silver coating on copper powder and its effects on oxidation resistance were investigated by varying the fabrication parameters. Using acetylacetone (C5H8O2) as chelating reagent, silver-coated copper powder was fabricated by displacement reaction method. In the process, acetylacetone forms chelating compound with Cu 2+, which prevent the formation of [Cu (NH3)4]2+. Therefore, Ag + can be reduced continully and deposited on the surface of copper particles. As-coated copper particles were characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM) and x-ray energy dispersive spectroscopy (EDS). The oxidation resistance of silver coated copper powder was investigated by gravimetric method. It was found that a fairly continuous silver layer was formed on the surface of copper powder by the electroless type of substitution plating. When the silver content reached 10 wt. %, silver was homogeneously distributed around the copper particles and few free silver particles were detected. The results showed that the silver coated copper powder with the best oxidation resistance was prepared at 40°C and the C5H8O2/AgNO3 molar ratio was 1:1.

  17. High-Emittance, Low-Absorbance Thermal-Control Coating

    NASA Technical Reports Server (NTRS)

    Le, Huong G.; Obrien, Dudley L.

    1993-01-01

    Modified process for anodizing 5657 aluminum alloy results in Al2O3 surfaces with infrared emissivities as great as 0.92 and solar absorptivities as small as 0.2. Coating enables fabrication of radiators requiring less surface, and hence less weight: radiators with coating weigh approximately 7 percent less than thermally equivalent radiators made with older anodizing processes. Coating applied easily and economically, and retains all of desirable properties of standard anodized coatings.

  18. Optical coating performance for heat reflectors of JWST-ISIM electronic component

    NASA Astrophysics Data System (ADS)

    Quijada, Manuel A.; Bousquet, Robert; Garrison, Matt; Perrygo, Chuck; Threat, Felix; Rashford, Robert

    2008-07-01

    The James Webb Space Telescope (JWST) consists of an infrared-optimized Optical Telescope Element (OTE) that is cooled down to 40 degrees Kelvin. A second adjacent component to the OTE is the Integrated Science Instrument Module, or ISIM. This module includes the electronic compartment, which provides the mounting surfaces and ambient thermally controlled environment for the instrument control electronics. Dissipating the 200 watts generated from the ISIM structure away from the OTE is of paramount importance so that the spacecraft's own heat does not interfere with the infrared light detected from distant cosmic sources. This technical challenge is overcome by a thermal subsystem unit that provides passive cooling to the ISIM control electronics. The proposed design of this thermal radiator consists of a lightweight structure made out of composite materials and low-emittance metal coatings. In this paper, we will present characterizations of the coating emittance, bidirectional reflectance, and mechanical structure design that will affect the performance of this passive cooling reflector.

  19. Understanding the role of dip-coating process parameters in the mechanical performance of polymer-coated bioglass robocast scaffolds.

    PubMed

    Motealleh, Azadeh; Eqtesadi, Siamak; Perera, Fidel Hugo; Pajares, Antonia; Guiberteau, Fernando; Miranda, Pedro

    2016-12-01

    The effect of different dip-coating variables-solvent, deposition temperature and polymer concentration-on the mechanical performance of polycaprolactone-coated 45S5 bioglass robocast scaffolds is systematically analyzed in this work. The reproducible geometry of the scaffolds produced by this additive manufacturing technique makes them an optimal model system and facilitates the analysis. The results suggest that the mechanical performance of the hybrid scaffolds is improved monotonically with polymer concentration, but this concentration cannot be increased indefinitely if the macroporosity interconnectivity, and thus the scaffold׳s capacity to promote tissue ingrowth, are to be preserved. An optimal concentration, and therefore viscosity (~1-4Pas in the present case), exists for any given set of process variables (scaffold geometry and material, polymer, solvent and process temperature) that yields coatings with optimal reinforcement and minimal reduction of scaffold functionality. Solvent and process temperature do not directly affect the strengthening provided by the polymeric coating. However they can determine the maximum concentration at the critical viscosity, and thereby the maximum achievable mechanical performance of the resulting hybrid scaffold. PMID:27522314

  20. Modeling controlled nutrient release from polymer coated fertilizers: diffusion release from single granules.

    PubMed

    Shaviv, Avi; Raban, Smadar; Zaidel, Elina

    2003-05-15

    A comprehensive model describing the complex and "non-Fickian" (mathematically nonlinear) nature of the release from single granules of membrane coated, controlled release fertilizers (CRFs) is proposed consisting of three stages: i. a lag period during which water penetrates the coating of the granule dissolving part of the solid fertilizer in it ii. a period of linear release during which water penetration into and release out occur concomitantly while the total volume of the granules remains practically constant; and iii. a period of "decaying release", starting as the concentration inside the granule starts to decrease. A mathematical model was developed based on vapor and nutrient diffusion equations. The model predicts the release stages in terms of measurable geometrical and chemophysical parameters such as the following: the product of granule radius and coating thickness, water and solute permeability, saturation concentration of the fertilizer, and its density. The model successfully predicts the complex and "sigmoidal" pattern of release that is essential for matching plant temporal demand to ensure high agronomic and environmental effectiveness. It also lends itself to more complex statistical formulations which account for the large variability within large populations of coated CRFs and can serve for further improving CRF production and performance. PMID:12785532

  1. Long-Term Anti-Corrosion Performance of a Conducting Polymer-Based Coating System for Steels

    NASA Astrophysics Data System (ADS)

    Pan, Tongyan; Yu, Qifeng

    2016-06-01

    The long-term durability of a two-layer coating system was evaluated by two accelerated corrosion tests, i.e., the ASTM B117 Salt spray test and the ASTM D5894 Cyclic salt fog/UV exposure test, and a series of surface analyses. The coating system was developed for protecting structural steels from corrosion, including a functional primer made of intrinsically conducting polymer (ICP) and a protective topcoat. The standard pull-off test per ASTM D4541 was employed for characterizing the adhesion of the coating systems to substrate, aided by visual examination of the surface deterioration of the samples. The ICP-based systems demonstrated superior long-term anti-corrosion capacity when a polyurethane topcoat is used. The ICP-based primer made of a waterborne epoxy gave poorer anti-corrosion performance than the ICP-based primer made of regular non-waterborne epoxy, which can be attributed to the lower adhesion the waterborne epoxy demonstrated to the substrate surface. The zinc-rich control systems showed good anti-corrosion durability; however, they may produce excessive oxidative products of zinc to cause coating delamination. Based on the test results, the two-layer coating system consisting of an ICP-based primer and a polyurethane topcoat outperforms the conventional zinc-rich coating systems for corrosion protection of steels.

  2. High performance magnetically controllable microturbines.

    PubMed

    Tian, Ye; Zhang, Yong-Lai; Ku, Jin-Feng; He, Yan; Xu, Bin-Bin; Chen, Qi-Dai; Xia, Hong; Sun, Hong-Bo

    2010-11-01

    Reported in this paper is two-photon photopolymerization (TPP) fabrication of magnetic microturbines with high surface smoothness towards microfluids mixing. As the key component of the magnetic photoresist, Fe(3)O(4) nanoparticles were carefully screened for homogeneous doping. In this work, oleic acid stabilized Fe(3)O(4) nanoparticles synthesized via high-temperature induced organic phase decomposition of an iron precursor show evident advantages in particle morphology. After modification with propoxylated trimethylolpropane triacrylate (PO(3)-TMPTA, a kind of cross-linker), the magnetic nanoparticles were homogeneously doped in acrylate-based photoresist for TPP fabrication of microstructures. Finally, a magnetic microturbine was successfully fabricated as an active mixing device for remote control of microfluids blending. The development of high quality magnetic photoresists would lead to high performance magnetically controllable microdevices for lab-on-a-chip (LOC) applications. PMID:20721411

  3. Lithium Surface Coatings for Improved Plasma Performance in NSTX

    SciTech Connect

    Kugel, H W; Ahn, J -W; Allain, J P; Bell, R; Boedo, J; Bush, C; Gates, D; Gray, T; Kaye, S; Kaita, R; LeBlanc, B; Maingi, R; Majeski, R; Mansfield, D; Menard, J; Mueller, D; Ono, M; Paul, S; Raman, R; Roquemore, A L; Ross, P W; Sabbagh, S; Schneider, H; Skinner, C H; Soukhanovskii, V; Stevenson, T; Timberlake, J; Wampler, W R

    2008-02-19

    NSTX high-power divertor plasma experiments have shown, for the first time, significant and frequent benefits from lithium coatings applied to plasma facing components. Lithium pellet injection on NSTX introduced lithium pellets with masses 1 to 5 mg via He discharges. Lithium coatings have also been applied with an oven that directed a collimated stream of lithium vapor toward the graphite tiles of the lower center stack and divertor. Lithium depositions from a few mg to 1 g have been applied between discharges. Benefits from the lithium coating were sometimes, but not always seen. These improvements sometimes included decreases plasma density, inductive flux consumption, and ELM frequency, and increases in electron temperature, ion temperature, energy confinement and periods of MHD quiescence. In addition, reductions in lower divertor D, C, and O luminosity were measured.

  4. Development of non-destructive inspection method for the performance of thermal barrier coating.

    PubMed

    Morinaga, M; Takahashi, T

    2001-05-01

    This paper shows that our proprietary non-destructive inspection method can be used to effectively measure the thermal barrier performance of the thermal barrier coating used to coat gas turbine hot parts by the results of numerical analysis and laboratory experiments. PMID:11460665

  5. Performance characteristics of zinc-rich coatings applied to carbon steel

    NASA Technical Reports Server (NTRS)

    Paton, W. J.

    1973-01-01

    A program was conducted to evaluate the performance of topcoated and untopcoated zinc-rich coatings. Sacrificial coatings of this type are required for protecting carbon steel structures from the aggressive KSC sea coast environment. A total of 59 commercially available zinc-rich coatings and 47 topcoated materials were exposed for an 18-month period. Test panels were placed in special racks placed approximately 30.5 m (100 feet) above the high tide line at the KSC Corrosion Test Site. Laboratory tests to determine the temperature resistance, abrasion resistance, and adhesion of the untopcoated zinc-rich coatings were also performed. It has been concluded that: (1) The inorganic types of zinc-rich coatings are far superior to the organic types in the KSC environment. (2) Organic zinc-rich coatings applied at 0.1 - 0.15 mm (4-6 mils) film thickness provide better corrosion protection than when applied at the manufacturers' recommended nominal film thickness of .08 mm (3 mils). (3) Topcoats are not necessary, or even desirable, when used in conjunction with zinc-rich coatings in the KSC environment. (4) Some types of inorganic zinc-rich coatings require an extended outdoor weathering period in order to obtain adequate mechanical properties. and (5) A properly formulated inorganic zinc-rich coating is not affected by a 24-hour thermal exposure to 400 C (752 F).

  6. Quality control of the tribological coating PS212

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.; Dellacorte, Christopher; Deadmore, Daniel L.

    1989-01-01

    PS212 is a self-lubricating, composite coating that is applied by the plasma spray process. It is a functional lubricating coating from 25 C (or lower) to 900 C. The coating is prepared from a blend of three different powders with very dissimilar properties. Therefore, the final chemical composition and lubricating effectiveness of the coatings are very sensitive to the process variables used in their preparation. Defined here are the relevant variables. The process and analytical procedures that will result in satisfactory tribological coatings are discussed.

  7. Biocatalytic coatings for air pollution control: a proof of concept study on VOC biodegradation.

    PubMed

    Estrada, José M; Bernal, Oscar I; Flickinger, Michael C; Muñoz, Raúl; Deshusses, Marc A

    2015-02-01

    Although biofilm-based biotechnologies exhibit a large potential as solutions for off-gas treatment, the high water content of biofilms often causes pollutant mass transfer limitations, which ultimately limit their widespread application. The present study reports on the proof of concept of the applicability of bioactive latex coatings for air pollution control. Toluene vapors served as a model volatile organic compound (VOC). The results showed that Pseudomonas putida F1 cells could be successfully entrapped in nanoporous latex coatings while preserving their toluene degradation activity. Bioactive latex coatings exhibited toluene specific biodegradation rates 10 times higher than agarose-based biofilms, because the thin coatings were less subject to diffusional mass transfer limitations. Drying and pollutant starvation were identified as key factors inducing a gradual deterioration of the biodegradation capacity in these innovative coatings. This study constitutes the first application of bioactive latex coatings for VOC abatement. These coatings could become promising means for air pollution control. PMID:25115963

  8. Effect of carbon coating on scuffing performance in diesel fuels

    SciTech Connect

    Ajayi, O. O.; Alzoubi, M. F.; Erdemir, A.; Fenske, G. R.

    2000-06-29

    Low-sulfur and low-aromatic diesel fuels are being introduced in order to reduce various types of emissions in diesel engines to levels in compliance with current and impending US federal regulations. The low lubricity of these fuels, however, poses major reliability and durability problems for fuel injection components that depend on diesel fuel for their lubrication. In the present study, the authors evaluated the scuff resistance of surfaces in regular diesel fuel containing 500 ppm sulfur and in Fischer-Tropsch synthetic diesel fuel containing no sulfur or aromatics. Tests were conducted with the high frequency reciprocating test rig (HFRR) using 52100 steel balls and H-13 tool-steel flats with and without Argonne's special carbon coatings. Test results showed that the sulfur-containing fuels provide about 20% higher scuffing resistance than does fuel without sulfur. Use of the carbon coating on the flat increased scuffing resistance in both regular and synthetic fuels by about ten times, as measured by the contact severity index at scuffing. Scuffing failure in tests conducted with coated surfaces did not occur until the coating had been removed by the two distinct mechanisms of spalling and wear.

  9. Fire Propagation Performance of Intumescent Fire Protective Coatings Using Eggshells as a Novel Biofiller

    PubMed Central

    Yew, M. C.; Ramli Sulong, N. H.; Yew, M. K.; Amalina, M. A.; Johan, M. R.

    2014-01-01

    This paper aims to synthesize and characterize an effective intumescent fire protective coating that incorporates eggshell powder as a novel biofiller. The performances of thermal stability, char formation, fire propagation, water resistance, and adhesion strength of coatings have been evaluated. A few intumescent flame-retardant coatings based on these three ecofriendly fire retardant additives ammonium polyphosphate phase II, pentaerythritol and melamine mixed together with flame-retardant fillers, and acrylic binder have been prepared and designed for steel. The fire performance of the coatings has conducted employing BS 476: Part 6-Fire propagation test. The foam structures of the intumescent coatings have been observed using field emission scanning electron microscopy. On exposure, the coated specimens' B, C, and D had been certified to be Class 0 due to the fact that their fire propagation indexes were less than 12. Incorporation of ecofriendly eggshell, biofiller into formulation D led to excellent performance in fire stopping (index value, (I) = 4.3) and antioxidation of intumescent coating. The coating is also found to be quite effective in water repellency, uniform foam structure, and adhesion strength. PMID:25136687

  10. Fire propagation performance of intumescent fire protective coatings using eggshells as a novel biofiller.

    PubMed

    Yew, M C; Ramli Sulong, N H; Yew, M K; Amalina, M A; Johan, M R

    2014-01-01

    This paper aims to synthesize and characterize an effective intumescent fire protective coating that incorporates eggshell powder as a novel biofiller. The performances of thermal stability, char formation, fire propagation, water resistance, and adhesion strength of coatings have been evaluated. A few intumescent flame-retardant coatings based on these three ecofriendly fire retardant additives ammonium polyphosphate phase II, pentaerythritol and melamine mixed together with flame-retardant fillers, and acrylic binder have been prepared and designed for steel. The fire performance of the coatings has conducted employing BS 476: Part 6-Fire propagation test. The foam structures of the intumescent coatings have been observed using field emission scanning electron microscopy. On exposure, the coated specimens' B, C, and D had been certified to be Class 0 due to the fact that their fire propagation indexes were less than 12. Incorporation of ecofriendly eggshell, biofiller into formulation D led to excellent performance in fire stopping (index value, (I) = 4.3) and antioxidation of intumescent coating. The coating is also found to be quite effective in water repellency, uniform foam structure, and adhesion strength. PMID:25136687

  11. Shuttle active thermal control system development testing. Volume 7: Improved radiator coating adhesive tests

    NASA Technical Reports Server (NTRS)

    Reed, M. W.

    1973-01-01

    Silver/Teflon thermal control coatings have been tested on a modular radiator system projected for use on the space shuttle. Seven candidate adhesives have been evaluated in a thermal vacuum test on radiator panels similar to the anticipated flight hardware configuration. Several classes of adhesives based on polyester, silicone, and urethane resin systems were tested. These included contact adhesives, heat cured adhesives, heat and pressure cured adhesives, pressure sensitive adhesives, and two part paint on or spray on adhesives. The coatings attached with four of the adhesives, two silicones and two urethanes, had no changes develop during the thermal vacuum test. The two silicone adhesives, both of which were applied to the silver/Teflon as transfer laminates to form a tape, offered the most promise based on application process and thermal performance. Each of the successful silicone adhesives required a heat and pressure cure to adhere during the cryogenic temperature excursion of the thermal-vacuum test.

  12. Effect of SOFC Interconnect-Coating Interactions on Coating Properties and Performance

    SciTech Connect

    Jeffrey W. Fergus

    2012-09-05

    The high operating temperature of solid oxide fuel cells (SOFCs) provides good fuel flexibility which expands potential applications, but also creates materials challenges. One such challenge is the interconnect material, which was the focus of this project. In particular, the objective of the project was to understand the interaction between the interconnect alloy and ceramic coatings which are needed to minimize chromium volatilization and the associated chromium poisoning of the SOFC cathode. This project focused on coatings based on manganese cobalt oxide spinel phases (Mn,Co)3O4, which have been shown to be effective as coatings for ferritic stainless steel alloys. Analysis of diffusion couples was used to develop a model to describe the interaction between (Mn,Co)3O4 and Cr2O3 in which a two-layer reaction zone is formed. Both layers form the spinel structure, but the concentration gradients at the interface appear like a two-phase boundary suggesting that a miscibility gap is present in the spinel solid solution. A high-chromium spinel layer forms in contact with Cr2O3 and grows by diffusion of manganese and cobalt from the coating material to the Cr2O3. The effect of coating composition, including the addition of dopants, was evaluated and indicated that the reaction rate could be decreased with additions of iron, titanium, nickel and copper. Diffusion couples using stainless steel alloys (which form a chromia scale) had some similarities and some differences as compared to those with Cr2O3. The most notable difference was that the high-chromium spinel layer did not form in the diffusion couples with stainless steel alloys. This difference can be explained using the reaction model developed in this project. In particular, the chromia scale grows at the expense of the alloy, the high-chromia layer grows at the expense of chromia scale and the high-chromia layer is consumed by diffusion of chromium into the coating material. If the last process (dissolution

  13. [Research advances on controlled-release mechanisms of nutrients in coated fertilizers].

    PubMed

    Zhang, Haijun; Wu, Zhijie; Liang, Wenju; Xie, Hongtu

    2003-12-01

    Using encapsulation techniques to coat easily soluble fertilizers is an important way to improve fertilizer use efficiency while reduce environmental hazards. Based on a wide range of literature collection on coated fertilizer research, the theories, processes, and characters of nutrient controlled-release from coated fertilizer were discussed, and the factors affecting nutrient controlled-release and the mathematical simulations on it were reviewed. The main tendencies related to this research in China were also put forward. PMID:15031946

  14. Performance of Al-Rich Oxidation Resistant Coatings For Fe-Base Alloys

    SciTech Connect

    Pint, Bruce A

    2010-01-01

    Aluminum-rich coatings made by chemical vapor deposition and pack cementation on ferritic (e.g. Fe-9Cr-1Mo) and austenitic (Type 304L) substrates are being evaluated at 650-800 C. For oxidation testing, a humid air environment was used to quantify coating performance, as uncoated substrates experience rapid oxidation at these temperatures. A main goal of this work is to demonstrate the potential benefits and problems with alumina-forming coatings. The higher exposure temperatures were selected to accelerate the degradation of the coating by interdiffusion with the substrate. A general conclusion of this testing was that coatings with less Al and a ferritic Fe(Al) structure could be more durable than higher Al content aluminide coatings which have a large thermal expansion mismatch with these substrates. A lifetime model has been developed using diffusion and oxidation observations to predict coating performance as a function of temperature and initial coating composition. To test and improve the model, additional experiments are now being conducted to determine the effect of substrate composition (e.g. Cr content using Fe-12Cr and Fe-9Cr-2W substrates) and exposure temperature on the critical Al content for coating failure. Because of the unexpectedly low level of Al measured at coating failure ({approx}3.5at.% at 700 C), exposures of specimens with thick ({approx}200 {mu}m) high Al content coatings were stopped after 10kh at 800 C and 20kh at 700 C because extremely long times to failure were predicted. Post-exposure Al concentration profiles for these specimens were measured using electron microprobe.

  15. Performance of Al-rich Oxidation Resistant Coatings for Fe-Base Alloys

    SciTech Connect

    Pint, Bruce A; Zhang, Ying

    2011-01-01

    Aluminum-rich coatings made by chemical vapor deposition and pack cementation on ferritic (e.g. Fe-9Cr-1Mo) and austenitic (Type 304L) substrates are being evaluated at 650-800 C. For oxidation testing, a humid air environment was used to quantify coating performance, as uncoated substrates experience rapid oxidation at these temperatures. A main goal of this work is to demonstrate the potential benefits and problems with alumina-forming coatings. The higher exposure temperatures were selected to accelerate the degradation of the coating by interdiffusion with the substrate. A general conclusion of this testing was that coatings with less Al and a ferritic Fe(Al) structure could be more durable than higher Al content aluminide coatings which have a large thermal expansion mismatch with these substrates. A lifetime model has been developed using diffusion and oxidation observations to predict coating performance as a function of temperature and initial coating composition. To test and improve the model, additional experiments are now being conducted to determine the effect of substrate composition (e.g. Cr content using Fe-12Cr and Fe-9Cr-2W substrates) and exposure temperature on the critical Al content for coating failure. Because of the unexpectedly low level of Al measured at coating failure ({approx}3.5 at.% at 700 C), exposures of specimens with thick ({approx}200 {micro}m) high Al content coatings were stopped after 10kh at 800 C and 20kh at 700 C because extremely long times to failure were predicted. Post-exposure Al concentration profiles for these specimens were measured using electron microprobe.

  16. Performance of Al-Rich Oxidation Resistant Coatings for Fe-Base Alloys

    SciTech Connect

    Pint, Bruce A; Zhang, Ying

    2009-01-01

    Aluminum-rich coatings made by chemical vapor deposition and pack cementation on ferritic (e.g. Fe-9Cr-1Mo) and austenitic (Type 304L) substrates are being evaluated at 650-800 C. For oxidation testing, a humid air environment was used to quantify coating performance, as uncoated substrates experience rapid oxidation at these temperatures. A main goal of this work is to demonstrate the potential benefits and problems with alumina-forming coatings. The higher exposure temperatures were selected to accelerate the degradation of the coating by interdiffusion with the substrate. A general conclusion of this testing was that coatings with less Al and a ferritic Fe(Al) structure could be more durable than higher Al content aluminide coatings which have a large thermal expansion mismatch with these substrates. A lifetime model has been developed using diffusion and oxidation observations to predict coating performance as a function of temperature and initial coating composition. To test and improve the model, additional experiments are now being conducted to determine the effect of substrate composition (e.g. Cr content using Fe-12Cr and Fe-9Cr-2W substrates) and exposure temperature on the critical Al content for coating failure. Because of the unexpectedly low level of Al measured at coating failure ({approx}3.5at.% at 700 C), exposures of specimens with thick ({approx}200 {micro}m) high Al content coatings were stopped after 10kh at 800 C and 20kh at 700 C because extremely long times to failure were predicted. Post-exposure Al concentration profiles for these specimens were measured using electron microprobe.

  17. Low Earth Orbit Environmental Durability of Recently Developed Thermal Control Coatings

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.

    2015-01-01

    The Materials International Space Station Experiment provided a means to expose materials and devices to the low Earth orbit environment on the exterior of the International Space Station. By returning the specimens to Earth after flight, the specimens could be evaluated by comparison with pre-flight measurements. One area of continuing interest is thermal control paints and coatings that are applied to exterior surfaces of spacecraft. Though traditional radiator coatings have been available for decades, recent work has focused on new coatings that offer custom deposition or custom optical properties. The custom deposition of interest is plasma spraying and one type of coating recently developed as part of a Small Business Innovative Research effort was designed to be plasma sprayed onto radiator surfaces. The custom optical properties of interest are opposite to those of a typical radiator coating, having a combination of high solar absorptance and low infrared emittance for solar absorber applications, and achieved in practice via a cermet coating. Selected specimens of the plasma sprayed coatings and the solar absorber coating were flown on Materials International Space Station Experiment 7, and were recently returned to Earth for post-flight analyses. For the plasma sprayed coatings in the ram direction, one specimen increased in solar absorptance and one specimen decreased in solar absorptance, while the plasma sprayed coatings in the wake direction changed very little in solar absorptance. For the cermet coating deployed in both the ram and wake directions, the solar absorptance increased. Interestingly, all coatings showed little change in infrared emittance.

  18. Reliability performance of titanium sputter coated Ni-Ti arch wires: mechanical performance and nickel release evaluation.

    PubMed

    Anuradha, P; Varma, N K Sapna; Balakrishnan, Avinash

    2015-01-01

    The present research was aimed at developing surface coatings on NiTi archwires capable of protection against nickel release and to investigate the stability, mechanical performance and prevention of nickel release of titanium sputter coated NiTi arch wires. Coated and uncoated specimens immersed in artificial saliva were subjected to critical evaluation of parameters such as surface analysis, mechanical testing, element release, friction coefficient and adhesion of the coating. Titanium coatings exhibited high reliability on exposure even for a prolonged period of 30 days in artificial saliva. The coatings were found to be relatively stable on linear scratch test with reduced frictional coefficient compared to uncoated samples. Titanium sputtering adhered well with the Ni-Ti substrates at the molecular level, this was further confirmed by Inductive coupled plasma emission spectroscopy (ICPE) analysis which showed no dissolution of nickel in the artificial saliva. Titanium sputter coatings seem to be promising for nickel sensitive patients. The study confirmed the superior nature of the coating, evident as reduced surface roughness, friction coefficient, good adhesion and minimal hardness and elastic modulus variations in artificial saliva over a given time period. PMID:26484557

  19. Improved engine performance via use of nickel ceramic composite coatings (NCC coat)

    SciTech Connect

    Funatani, K.; Kurosawa, K.; Fabiyi, P.A.; Puz, M.F.

    1994-09-01

    In seeking to produce lightweight aluminum block based engines, a variety of metallurgical and surface modification techniques for cylinder bores, pistons and piston rings are available. This paper discusses these various alternative methods while placing particular emphasis on electroplated nickel ceramic composite coatings (NCC). NCC Coating properties are characterized by high hardness, high corrosion resistance, high temperature wear and scuff resistance and low frictional coefficients. The application of NCC Coatings in 2-stroke motorcycle and diesel engines has resulted in benefits in the following areas: elimination of cast iron liners; reduced cylinder wall temperature, engine weight and increased power; lowering of oil consumption; improved fuel economy; reduction in emissions; improved scuff and wear resistance on cylinder bores, pistons and piston rings; friction reduction; combating of piston ring groove microwelding and pound out; thermal barrier protection on diesel piston domes; reduction in carbon deposition on piston domes; reduced noise from piston slap; and ability to operate in corrosive environments. The sum of the above stated benefits holds much potential for contributing towards greater flexibility in materials selection for the design of lightweight, fuel efficient vehicles based upon the use of aluminum engines. 13 refs., 13 figs.

  20. Composite neutron absorbing coatings for nuclear criticality control

    DOEpatents

    Wright, Richard N.; Swank, W. David; Mizia, Ronald E.

    2005-07-19

    Thermal neutron absorbing composite coating materials and methods of applying such coating materials to spent nuclear fuel storage systems are provided. A composite neutron absorbing coating applied to a substrate surface includes a neutron absorbing layer overlying at least a portion of the substrate surface, and a corrosion resistant top coat layer overlying at least a portion of the neutron absorbing layer. An optional bond coat layer can be formed on the substrate surface prior to forming the neutron absorbing layer. The neutron absorbing layer can include a neutron absorbing material, such as gadolinium oxide or gadolinium phosphate, dispersed in a metal alloy matrix. The coating layers may be formed by a plasma spray process or a high velocity oxygen fuel process.

  1. Robotic weld overlay coatings for erosion control. Quarterly progress report, October 1993--December 1993

    SciTech Connect

    Levin, B.F.; DuPont, J.N.; Marder, A.R.

    1994-01-20

    Research is being conducted to develop criteria for selecting weld overlay coatings for erosion mitigation in Circulated Fluidized Beds. Twelve weld overlay alloys were deposited on 1018 steel substrates using plasma arc welding. Ten samples from each coating were prepared for erosion testing. All selected coatings were erosion tested at 400C and their erosion resistance and microstructure evaluated. Steady state erosion rates were similar for several weld overlay coatings (Ultimet, Inconel-625, Iron-Aluminide, 316L SS, and High Chromium Cast Iron) and were considerably lower than the remaining coating evaluated. These coatings had different base (Co, Fe, Ni-base). No correlations were found between room temperature microhardness of the weld overlay coatings and their erosion resistance at elevated temperature, although this criteria is often thought to be an indicator of erosion resistance. It was suggested that the coatings that showed similar erosion rates may have similar mechanical properties such as fracture strength, toughness and work hardening rates at this temperature. During the past quarter, Iron-Aluminide, Inconel-625, and 316L SS coatings were selected for more detailed investigations based upon the preliminary erosion test results. Microhardness tests were performed on eroded samples to determine the size of the work hardened zone and change in coatings hardness due to erosion. The work hardened zone was to correlated with erosion resistance of the coatings. Additional Iron-Aluminide, Inconel-625, and 316L SS coatings were deposited on 1018 steel substrates.

  2. Adhesive Performance of Biomimetic Adhesive-Coated Biologic Scaffolds

    PubMed Central

    Murphy, John L.; Vollenweider, Laura; Xu, Fangmin; Lee, Bruce P.

    2010-01-01

    Surgical repair of a discontinuity in traumatized or degenerated soft tissues is traditionally accomplished using sutures. A current trend is to reinforce this primary repair with surgical grafts, meshes, or patches secured with perforating mechanical devices (i.e., sutures, staples, or tacks). These fixation methods frequently lead to chronic pain and mesh detachment. We developed a series of biodegradable adhesive polymers that are synthetic mimics of mussel adhesive proteins (MAPs), composed of 3,4-dihydroxyphenylalanine (DOPA)-derivatives, polyethylene glycol (PEG), and polycaprolactone (PCL). These polymers can be cast into films, and their mechanical properties, extent of swelling, and degradation rate can be tailored through the composition of the polymers as well as blending with additives. When coated onto a biologic mesh used for hernia repair, these adhesive constructs demonstrated adhesive strengths significantly higher than fibrin glue. With further development, a pre-coated bioadhesive mesh may represent a new surgical option for soft tissue repair. PMID:20919699

  3. Performance of coatings for concrete exposed to pesticides and fertilizer

    SciTech Connect

    Broder, M.F.; Nguyen, D.T.; Zarate, E.A.

    1994-12-31

    As a result of Congressional amendments for the reauthorization of the Federal Insecticide Fungicide and Rodenticide Act (known as FIFRA 1988), EPA is proposing minimum standards for secondary containment of pesticide bulk containers and for containment structures for certain pesticide dispensing operations. Concrete is the most common secondary containment construction material for pesticides but concrete may be susceptible to migration of spilled pesticides due to its porosity and potential for cracking. The research described here was requested by EPA`s Office of Pesticide Programs to help identify coatings for concrete that could reduce the migration of pesticides through containment structures. At the time of this writing, the study was about half completed. Preliminary results from twelve generic coating types are discussed.

  4. Performance of thermal barrier coatings in high heat flux environments

    NASA Technical Reports Server (NTRS)

    Miller, R. A.; Berndt, C. C.

    1984-01-01

    Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 C after 0.5 sec in the flame. An as-sprayed ZrO2-8%Y2O3 specimens survived 3000 of the 0.5 sec cycles with failing. Surface spalling was observed when 2.5 sec cycles were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 2 cycle from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO2-12%Y2O3 or ZrO2-20%Y2O3 were shown to be unsuited for use under the high heat flux conditions of this study.

  5. Performance of thermal barrier coatings in high heat flux environments

    NASA Technical Reports Server (NTRS)

    Miller, R. A.; Berndt, C. C.

    1984-01-01

    Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 C after 0.5 sec in the flame. An as-sprayed ZrO2-8 percent Y2O3 specimens survived 3000 of the 0.5 sec cycles with falling. Surface spalling was observed when 2.5 sec cycles were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 1 cycle from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO2-12 percent Y2O3 or ZrO2-2O percent Y2O3 were shown to be unsuited for use under the high heat flux conditions of this study.

  6. Performance of thermal barrier coatings in high heat flux environments

    NASA Technical Reports Server (NTRS)

    Miller, R. A.; Berndt, C. C.

    1984-01-01

    Thermal barrier coatings were exposed to the high temperature and high heat flux produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 C after 0.5 sec in the flame. An as-sprayed ZrO2-8 percent Y203 specimens survived 3000 of the 0.5 sec cycles with failing. Surface spalling was observed when 2.5 sec cycles were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 2 cycle from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO2-12 percent Y2O3 or ZrO2-20 percent Y2O3 were shown to be unsuited for use under the high heat flux conditions of this study.

  7. Synthesis of boron nitride coatings on quartz fibers: Thickness control and mechanism research

    NASA Astrophysics Data System (ADS)

    Zheng, Yu; Wang, Shubin

    2011-10-01

    Boron nitride (BN) coatings were successfully synthesized on quartz fibers by dip-coating in boric acid and urea solutions at 700 °C. The SEM micrographs indicated that the quartz fibers were fully covered by coatings with smooth surface. The XRD, FT-IR, XPS spectra and HR-TEM results showed that the composition of the coatings which combined closely with the quartz fibers was polycrystalline h-BN. By changing the dip circles, the coating thickness was well controlled. The thicknesses of samples dipped less than six circles increased linearly with dipping-circles; and the increment of coating thickness would slow down when the fibers were dipped 10 circles. After being dipped for 10 circles, the thickness was about 300 nm. The coating thickness was also established by calculation and the calculated results were consistent with the results measured by micrograph.

  8. Chitosan coatings to control release and target tissues for therapeutic delivery.

    PubMed

    Jennings, Jessica Amber; Wells, Carlos Montez; McGraw, Gregory S; Velasquez Pulgarin, Diego A; Whitaker, Marsalas D; Pruitt, Reginald L; Bumgardner, Joel David

    2015-07-01

    The natural biopolymer chitosan has versatile applications in therapeutic delivery. Coating drug delivery matrices or biomaterials with chitosan offers several advantages in drug delivery, including control of drug release, slowing degradation rate and improving biocompatibility. Advanced uses of chitosan in coating form include targeting drug delivery vehicles to specific tissue as well as providing a stimulus-controlled release response. The present review summarizes the current applications of chitosan coatings in the context of different biomaterial delivery technologies, as well as future directions of chitosan coatings for drug delivery technologies under development. PMID:26228776

  9. Erosion Performance of HVOF-Sprayed Cr3C2-NiCr Coatings

    NASA Astrophysics Data System (ADS)

    Ji, Gang-Chang; Li, Chang-Jiu; Wang, Yu-Yue; Li, Wen-Ya

    2007-12-01

    Cr3C2-NiCr coatings were deposited by high-velocity oxygen fuel (HVOF) spraying process under spray conditions of different flows of oxygen and propane gases, and spray distances. The orthogonal regression experimental design method was used for systematic investigation of the influence of spray parameters on the erosion performance of Cr3C2-NiCr coatings. Erosion tests were performed at different jet angles of abrasive particles. The erosion mechanism of Cr3C2-NiCr coatings was examined through the surface morphology and cross-sectional microstructure of the eroded coatings. The correlations of the carbide particle size and carbide content with the erosion rate were examined. It was found that the erosion occurred dominantly by spalling of splats from the lamellar interfaces. The spalling resulted from the propagation of cracks parallel to the interfaces between the lamellae exposed to the surface and underlying coating. The carbide particle size and content in the coating influenced significantly the erosion performance of Cr3C2-NiCr coatings.

  10. Environmental Barrier Coatings for Turbine Engines: A Design and Performance Perspective

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Fox, Dennis S.; Ghosn, Louis; Smialek, James L.; Miller, Robert A.

    2009-01-01

    Ceramic thermal and environmental barrier coatings (TEBC) for SiC-based ceramics will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating long-term durability remains a major concern with the ever-increasing temperature, strength and stability requirements in engine high heat-flux combustion environments, especially for highly-loaded rotating turbine components. Advanced TEBC systems, including nano-composite based HfO2-aluminosilicate and rare earth silicate coatings are being developed and tested for higher temperature capable SiC/SiC ceramic matrix composite (CMC) turbine blade applications. This paper will emphasize coating composite and multilayer design approach and the resulting performance and durability in simulated engine high heat-flux, high stress and high pressure combustion environments. The advances in the environmental barrier coating development showed promise for future rotating CMC blade applications.

  11. Performance of Ultra Hard Carbon Wear Coatings on Microgears Fabricated by Liga

    SciTech Connect

    Ager III, J.W.; Brown, I.G.; Christenson, T.R.; Dugger, M.T.; Follstaedt, D.M.; Knapp, J.A.; Monteiro, O.R.

    1998-12-18

    Stiction and friction are of concern for the reliable, long-term application of Ni-alloy micromachines. We have found that the application of a 30-70 nm hard carbon coating produces a significant reduction in the friction coefficient and wear rate of electroformed Ni substrates in reciprocating sliding contact under simulated MEMS operating conditions. To evaluate the performance of coated components, a series of 70-pm-thick microgears ranging in diameter from 0.2 to 2.2 mm were fabricated from electroformed Ni via standard LIGA processes and fixtured on posts in preparation for the coating procedure. A pulsed vacuum- arc deposition process was used to deposit a carbon coating on the gears with the plasma incident at a shallow angle to the gears' top surface. A sample bias of -2 keV was used in order to produce a coating with relatively low stress and good adhesion while maintaining high hardness. This coating process is known to be somewhat comformal to the component surfaces. The coating uniformity, particularly in the high-aspect-ratio areas between the gear teeth, was evaluated with micro-Raman spectroscopy. It is shown that the coating can be applied uniformly on the top gear surface. Between the gear teeth the coating was the same thickness as on top of the gear down to a point 50 ~m below the top surface. Below that point (i.e. between 50 and 70 Lm), the coating thickness is somewhat thinner, but is still present. These results demonstrate that it is possible to a deposit hard carbon coating on microgears to reduce friction and wear in micromachines.

  12. Radiation control coatings installed on federal buildings at Tyndall Air Force Base. Volume 1: Pre-coating monitoring and fresh coating results

    SciTech Connect

    Petrie, T.W.; Childs, P.W.

    1997-02-01

    The US Department of Energy`s (DOE`s) Federal Energy Management Program (FEMP) supports efforts to reduce energy use and associated expenses in the federal sector. One such effort, the New Technology Demonstration Program (NTDP), seeks to evaluate new energy-saving US technologies and secure their more timely adoption by the US government. Through a partnership with a federal site, the utility serving the site, a manufacturer of an energy-related technology, and other organizations associated with these interests, DOE can evaluate a new technology. The results of the program give federal agency decision makers more hands-on information with which to validate a decision to utilize a new technology in their facilities. The partnership of these interests is secured through a cooperative research and development agreement (CRADA), in this case between Lockheed Martin Energy Research Corporation, the manager of the Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee, and ThermShield International, Ltd., the manufacturer of the technology. This is the first volume of a two-volume report that describes the effects of radiation control coatings installed on federal buildings at Tyndall Air Force Base (AFB) in Florida by ThermShield International. ORNL`s Buildings Technology Center (BTC) was assigned the responsibility for gathering, analyzing, and reporting on the data to describe the effects of the coatings. This volume describes the monitoring plan and its implementation, the results of pre-coating monitoring, the coating installation, results from fresh coatings compared to pre-coating results, and a plan to decommission the monitoring equipment. By including results from roofs at Tyndall AFB and from an outdoor test facility at the BTC, the data cover the range from poorly insulated to well-insulated roofs and two kinds of radiation control coatings on various roof membranes.

  13. Development of porcelain enamel passive thermal control coatings

    NASA Technical Reports Server (NTRS)

    Levin, H.; Lent, W. E.; Buettner, D. H.

    1973-01-01

    A white porcelain enamel coating was developed for application to high temperature metallic alloy substrates on spacecraft. The coating consists of an optically opacifying zirconia pigment, a lithia-zirconia-silica frit, and an inorganic pigment dispersant. The coating is fired at 1000 to 1150 C to form the enamel. The coating has a solar absorptance of 0.22 and a total normal emittance of 0.82 for a 0.017 cm thick coating. The coating exhibits excellent adhesion, cleanability, and integrity and is thermal shock resistant to 900 C. Capability to coat large panels has been demonstrated by successful coating of 30 cm x 30 cm Hastelloy X alloy panels. Preliminary development of low temperature enamels for application to aluminum and titanium alloy substrates was initiated. It was determined that both leaded and leadless frits were feasible when applied with appropriate mill fluxes. Indications were that opacification could be achieved at firing temperatures below 540 C for extended periods of time.

  14. Polarization compensating protective coatings for TPF-Coronagraph optics to control contrast degrading cross polarization leakage

    NASA Technical Reports Server (NTRS)

    Balasubramanian, Kunjithapatham; Hoppe, Daniel J.; Mouroulis, Pantazis Z.; Marchen, Luis F.; Shaklan, Stuart B.

    2005-01-01

    We describe here the design approaches and performance analysis of the OTA in the wavelength band of interest. Coronagraph performance at 600nm wavelength based on a particular coating and occulting focal plane mask is also presented.

  15. Tailoring of silver wires and their performance as transparent conductive coatings.

    PubMed

    Lu, Y C; Chou, K S

    2010-05-28

    A feasible way to manipulate the scales of Ag wires through the polyol process is presented. By adjusting the amounts of either Pd or Ag precursor used in this process, we demonstrated the ability to control the scale of the wires. The presence of Pd ultrafine particles reduced by EG in advance served as the nuclei for inducing the subsequent formation of Ag wires, and the diameter of the resulting wires was observed to be inversely proportional to the quantity of Pd added. Further, the wire length was demonstrated to be proportional to and highly correlated with the total amount of Ag added, by a linear relationship. A glass plate coated with Ag wire film by the spray method is shown to be both transparent and conductive. The effect of scaling the wires on their performance is also discussed. PMID:20431210

  16. Particle Size Control of Polyethylene Glycol Coated Fe Nanoparticles

    NASA Astrophysics Data System (ADS)

    Srinivasan, B.; Bonder, M. J.; Zhang, Y.; Gallo, D.; Hadjipanayis, G. C.

    2006-03-01

    Recent interest in Fe nanoparticles with high magnetization is driven by their potential use in biomedical applications such as targeted drug delivery, MRI contrast enhancement and hyperthermia treatment of cancer. This study looks at the use of a polyethylene glycol (PEG) solution to mediate the particle size and therefore control the coercivity of the resulting nanoparticles. Iron nanoparticles were synthesized using an aqueous sodium borohydride reduction of ferrous chloride by a simultaneous introduction of reagents in a Y- junction. The resulting product was collected in a vessel containing a 15 mg/ml carboxyl terminated polyethylene glycol (cPEG) in ethyl alcohol solution located under the Y junction. By varying the length of tubing below the Y junction, the particle size was varied from 5-25 nm. X-ray diffraction data indicates the presence of either amorphous Fe-B or crystalline alpha Fe, depending on the molar ratio of reagents. Magnetic measurements indicate the particles are ferromagnetic with values of coercivity ranging from 200-500 Oe and a saturation magnetization in range of 70-110 emu/g. The XRD shows that the particles are not affected by the polymer coating.

  17. Test station development for laser-induced optical damage performance of broadband multilayer dielectric coatings

    NASA Astrophysics Data System (ADS)

    Kafka, K. R. P.; Chowdhury, E. A.; Negres, R. A.; Stolz, C. J.; Bude, J. D.; Bayramian, A. J.; Marshall, C. D.; Spinka, T. M.; Haefner, C. L.

    2015-11-01

    Laser-induced damage threshold (LIDT) testing was performed on commercially-available multilayer dielectric coatings to qualify for use in the High Repetition-Rate Advanced Petawatt Laser System (HAPLS) for Extreme Light Infrastructure Beamlines. Various tests were performed with uncompressed pulses (150 ps) from a 780 nm-centered Ti:Sapphire regenerative ampliflier, and the raster scan method was used to determine the best-performing coatings. Performance varied from 2-8 J/cm2 across samples from 6 different manufacturers.

  18. Effect of Heat Treatment on Mechanical Properties and Corrosion Performance of Cold-Sprayed Tantalum Coatings

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Vidyasagar, V.; Jyothirmayi, A.; Joshi, S. V.

    2016-04-01

    The cold-spray technique is of significant interest to deposit refractory metals with relatively high melting point for a variety of demanding applications. In the present study, mechanical properties of cold-sprayed tantalum coatings heat treated at different temperatures were investigated using microtensile testing, scratch testing, and nanoindentation. The corrosion performance of heat-treated coatings was also evaluated in 1 M KOH solution, and potentiodynamic polarization as well as impedance spectroscopy studies were carried out. Assessment of structure-property correlations was attempted based on microstructure, porosity, and intersplat bonding state, together with mechanical and corrosion properties of the heat-treated cold-sprayed tantalum coatings. Coatings annealed at 1500 °C, which is very close to the recrystallization temperature of tantalum, were found to perform almost as bulk tantalum, with exciting implications for various applications.

  19. Performance of a CsBr coated Nb photocathode at room temperature

    SciTech Connect

    Maldonado, Juan R.; Pianetta, Piero; Dowell, David H.; Smedley, John; Kneisel, Peter

    2010-01-15

    Experiments performed on Nb substrates coated with thin films of CsBr indicate a substantial enhancement of 150 to 800 times of the photoyield at 257 nm relative to the uncoated substrates. Results are presented for several power density illuminations and sample thickness. Further enhancement of photoyield was observed when the laser illumination was interrupted for a short time in samples with 5-10 nm thick CsBr coatings.

  20. Performance of composite coatings in a coal-fired boiler environment

    SciTech Connect

    Nava, J.C.

    2009-09-15

    Four samples of thermal spray coatings, each made from different core wire consumables by twin wire arc spray, were exposed for 18 months in a coal-fired boiler environment. The tests are described and the performance of each coating is evaluated. Results indicated that the four consumable wire alloys showed remarkable resistance to fly ash erosion and corrosion over the period of the test.

  1. Versatile surface engineering of porous nanomaterials with bioinspired polyphenol coatings for targeted and controlled drug delivery

    NASA Astrophysics Data System (ADS)

    Li, Juan; Wu, Shuxian; Wu, Cuichen; Qiu, Liping; Zhu, Guizhi; Cui, Cheng; Liu, Yuan; Hou, Weijia; Wang, Yanyue; Zhang, Liqin; Teng, I.-Ting; Yang, Huang-Hao; Tan, Weihong

    2016-04-01

    The development of biocompatible drug delivery systems with targeted recognition and controlled release has experienced a number of design challenges, including, for example, complicated preparation steps and premature drug release. Herein, we address these problems through an in situ self-polymerization method that synthesizes biodegradable polyphenol-coated porous nanomaterials for targeted and controlled drug delivery. As a proof of concept, we synthesized polyphenol-coated mesoporous silica nanoparticles, termed MSN@polyphenol. The polyphenol coatings not only improved colloidal stability and prevented premature drug leakage, but also provided a scaffold for immobilization of targeting moieties, such as aptamers. Both immobilization of targeting aptamers and synthesis of polyphenol coating are easily accomplished without the aid of any other organic reagents. Importantly, the polyphenol coating (EGCg) used in this study could be biodegraded by acidic pH and intracellular glutathione, resulting in the release of trapped anticancer drugs. Based on confocal fluorescence microscopy and cytotoxicity experiments, drug-loaded and polyphenol-coated MSNs were shown to possess highly efficient internalization and an apparent cytotoxic effect on target cancer, but not control, cells. Our results suggest that these highly biocompatible and biodegradable polyphenol-coated MSNs are promising vectors for controlled-release biomedical applications and cancer therapy.The development of biocompatible drug delivery systems with targeted recognition and controlled release has experienced a number of design challenges, including, for example, complicated preparation steps and premature drug release. Herein, we address these problems through an in situ self-polymerization method that synthesizes biodegradable polyphenol-coated porous nanomaterials for targeted and controlled drug delivery. As a proof of concept, we synthesized polyphenol-coated mesoporous silica nanoparticles

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

    NASA Technical Reports Server (NTRS)

    Hribar, V. F.; Bauer, J. L.; O'Donnell, T. P.

    1986-01-01

    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.

  3. Fluorescence measurements of the thermal control experiments coatings on LDEF S0069 and A0114

    NASA Technical Reports Server (NTRS)

    Zwiener, J. M.; Mell, R. J.; Peters, P. N.; Gregory, J. C.; Wilkes, D. R.; Miller, E. R.

    1993-01-01

    Fluorescence measurements were made on the thermal control coatings from the Long Duration Experiment Facility (LDEF) S0069, Thermal Control Surfaces Experiment (TCSE); and the A0114, Interaction of Atomic Oxygen with Material Surfaces in Low Earth orbit. Fluorescence was observed in two types of thermal control coatings and is attributed to pigments or binders. In addition, fluorescence measurement on the silver Teflon from the front cover of TCSE led to confirmation of damage (cracking) to the metal layers during application.

  4. Biodegradable, elastomeric coatings with controlled anti-proliferative agent release for magnesium-based cardiovascular stents.

    PubMed

    Gu, Xinzhu; Mao, Zhongwei; Ye, Sang-Ho; Koo, Youngmi; Yun, Yeoheung; Tiasha, Tarannum R; Shanov, Vesselin; Wagner, William R

    2016-08-01

    Vascular stent design continues to evolve to further improve the efficacy and minimize the risks associated with these devices. Drug-eluting coatings have been widely adopted and, more recently, biodegradable stents have been the focus of extensive evaluation. In this report, biodegradable elastomeric polyurethanes were synthesized and applied as drug-eluting coatings for a relatively new class of degradable vascular stents based on Mg. The dynamic degradation behavior, hemocompatibility and drug release were investigated for poly(carbonate urethane) urea (PCUU) and poly(ester urethane) urea (PEUU) coated magnesium alloy (AZ31) stents. Poly(lactic-co-glycolic acid) (PLGA) coated and bare stents were employed as control groups. The PCUU coating effectively slowed the Mg alloy corrosion in dynamic degradation testing compared to PEUU-coated, PLGA-coated and bare Mg alloy stents. This was confirmed by electron microscopy, energy-dispersive x-ray spectroscopy and magnesium ion release experiments. PCUU-coating of AZ31 was also associated with significantly reduced platelet adhesion in acute blood contact testing. Rat vascular smooth muscle cell (rSMC) proliferation was successfully inhibited when paclitaxel was released from pre-loaded PCUU coatings. The corrosion retardation, low thrombogenicity, drug loading capacity, and high elasticity make PCUU an attractive option for drug eluting coating on biodegradable metallic cardiovascular stents. PMID:27085049

  5. Nano-structural bioactive gradient coating fabricated by computer controlled plasma-spraying technology.

    PubMed

    Ning, C Y; Wang, Y J; Lu, W W; Qiu, Q X; Lam, R W M; Chen, X F; Chiu, K Y; Ye, J D; Wu, G; Wu, Z H; Chow, S P

    2006-10-01

    The poor mechanical property of hydroxyapatite was the major problem for load bearing and implant coating in clinical applications. To overcome this weakness, a bioactive gradient coating with a special design composition of hydroxyapatite (HA), ZrO2, Ti, bioglass was developed. This 120 microm coating with an upper layer of 30-50 microm porous HA produced by computer controlled plasma spraying which maintained energy level of the plasma which ensure proper melting of powder. The crystal size of the coating was 18.6-26.2 nm. Transformation of t-ZrO2 to m-ZrO2 reduced the thermal stress that weakened the coating and lowered down interfacial strength of the coating and metal substrate. Thermal stress of sprayed coating was 16.4 MPa which was much smaller than the sample without thermal treatment of 67.1 MPa. Interfacial strength between the coating and metal substrate was 53 MPa which is much higher than conventional Hydroxyapatite coating. Based on XRD analysis crystallinity of HA approached 98%. Therefore, high temperature treatment improved long term stability of the coating through improved crystallinity of hydroxyapatite and reduced other impure calcium phosphate phase. PMID:16977384

  6. Antimicrobial PVK:SWNT nanocomposite coated membrane for water purification: performance and toxicity testing.

    PubMed

    Ahmed, Farid; Santos, Catherine M; Mangadlao, Joey; Advincula, Rigoberto; Rodrigues, Debora F

    2013-08-01

    This study demonstrated that coated nitrocellulose membranes with a nanocomposite containing 97% (wt%) of polyvinyl-N-carbazole (PVK) and 3% (wt%) of single-walled carbon nanotubes (SWNTs) (97:3 wt% ratio PVK:SWNT) achieve similar or improved removal of bacteria when compared with 100% SWNTs coated membranes. Membranes coated with the nanocomposite exhibited significant antimicrobial activity toward Gram-positive and Gram-negative bacteria (≈ 80-90%); and presented a virus removal efficiency of ≈ 2.5 logs. Bacterial cell membrane damage was considered a possible mechanism of cellular inactivation since higher efflux of intracellular material (Deoxyribonucleic acid, DNA) was quantified in the filtrate of PVK-SWNT and SWNT membranes than in the filtrate of control membranes. To evaluate possible application of these membrane filters for drinking water treatment, toxicity of PVK-SWNT was tested against fibroblast cells. The results demonstrated that PVK-SWNT was non toxic to fibroblast cells as opposed to pure SWNT (100%). These results suggest that it is possible to synthesize antimicrobial nitrocellulose membranes coated with SWNT based nanocomposites for drinking water treatment. Furthermore, membrane filters coated with the nanocomposite PVK-SWNT (97:3 wt% ratio PVK:SWNT) will produce more suitable coated membranes for drinking water than pure SWNTs coated membranes (100%), since the reduced load of SWNT in the nanocomposite will reduce the use of costly and toxic SWNT nanomaterial on the membranes. PMID:23545165

  7. Effect of surface coating with magnesium stearate via mechanical dry powder coating approach on the aerosol performance of micronized drug powders from dry powder inhalers.

    PubMed

    Zhou, Qi Tony; Qu, Li; Gengenbach, Thomas; Larson, Ian; Stewart, Peter J; Morton, David A V

    2013-03-01

    The objective of this study was to investigate the effect of particle surface coating with magnesium stearate on the aerosolization of dry powder inhaler formulations. Micronized salbutamol sulphate as a model drug was dry coated with magnesium stearate using a mechanofusion technique. The coating quality was characterized by X-ray photoelectron spectroscopy. Powder bulk and flow properties were assessed by bulk densities and shear cell measurements. The aerosol performance was studied by laser diffraction and supported by a twin-stage impinger. High degrees of coating coverage were achieved after mechanofusion, as measured by X-ray photoelectron spectroscopy. Concomitant significant increases occurred in powder bulk densities and in aerosol performance after coating. The apparent optimum performance corresponded with using 2% w/w magnesium stearate. In contrast, traditional blending resulted in no significant changes in either bulk or aerosolization behaviour compared to the untreated sample. It is believed that conventional low-shear blending provides insufficient energy levels to expose host micronized particle surfaces from agglomerates and to distribute guest coating material effectively for coating. A simple ultra-high-shear mechanical dry powder coating step was shown as highly effective in producing ultra-thin coatings on micronized powders and to substantially improve the powder aerosolization efficiency. PMID:23196863

  8. Contamination control in hybrid microelectronic modules. Part 2: Selection and evaluation of coating materials

    NASA Technical Reports Server (NTRS)

    Himmel, R. P.

    1975-01-01

    The selection, test, and evaluation of organic coating materials for contamination control in hybrid circuits is reported. The coatings were evaluated to determine their suitability for use as a conformal coating over the hybrid microcircuit (including chips and wire bonds) inside a hermetically sealed package. Evaluations included ease of coating application and repair and effect on thin film and thick film resistors, beam leads, wire bonds, transistor chips, and capacitor chips. The coatings were also tested for such properties as insulation resistance, voltage breakdown strength, and capability of immobilizing loose particles inside the packages. The selected coatings were found to be electrically, mechanically, and chemically compatible with all components and materials normally used in hybrid microcircuits.

  9. Evaluation of Thermal Control Coatings for Flexible Ceramic Thermal Protection Systems

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius; Carroll, Carol; Smith, Dane; Guzinski, Mike; Marschall, Jochen; Pallix, Joan; Ridge, Jerry; Tran, Duoc

    1997-01-01

    This report summarizes the evaluation and testing of high emissivity protective coatings applied to flexible insulations for the Reusable Launch Vehicle technology program. Ceramic coatings were evaluated for their thermal properties, durability, and potential for reuse. One of the major goals was to determine the mechanism by which these coated blanket surfaces become brittle and try to modify the coatings to reduce or eliminate embrittlement. Coatings were prepared from colloidal silica with a small percentage of either SiC or SiB6 as the emissivity agent. These coatings are referred to as gray C-9 and protective ceramic coating (PCC), respectively. The colloidal solutions were either brushed or sprayed onto advanced flexible reusable surface insulation blankets. The blankets were instrumented with thermocouples and exposed to reentry heating conditions in the Ames Aeroheating Arc Jet Facility. Post-test samples were then characterized through impact testing, emissivity measurements, chemical analysis, and observation of changes in surface morphology. The results show that both coatings performed well in arc jet tests with backface temperatures slightly lower for the PCC coating than with gray C-9. Impact testing showed that the least extensive surface destruction was experienced on blankets with lower areal density coatings.

  10. Oxidation Control of Atmospheric Plasma Sprayed FeAl Intermetallic Coatings Using Dry-Ice Blasting

    NASA Astrophysics Data System (ADS)

    Song, Bo; Dong, Shujuan; Coddet, Pierre; Hansz, Bernard; Grosdidier, Thierry; Liao, Hanlin; Coddet, Christian

    2013-03-01

    The performance of atmospheric plasma sprayed FeAl coatings has been remarkably limited because of oxidation and phase transformation during the high-temperature process of preparation. In the present work, FeAl intermetallic coatings were prepared by atmospheric plasma spraying combined with dry-ice blasting. The microstructure, oxidation, porosity, and surface roughness of FeAl intermetallic coatings were investigated. The results show that a denser FeAl coating with a lower content of oxide and lower degree of phase transformation can be achieved because of the cryogenic, the cleaning, and the mechanical effects of dry-ice blasting. The surface roughness value decreased, and the adhesive strength of FeAl coating increased after the application of dry-ice blasting during the atmospheric plasma spraying process. Moreover, the microhardness of the FeAl coating increased by 72%, due to the lower porosity and higher dislocation density.