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Sample records for fluorocarbon coatings resisting

  1. water-soluble fluorocarbon coating

    NASA Technical Reports Server (NTRS)

    Nanelli, P.

    1979-01-01

    Water-soluble fluorocarbon proves durable nonpolluting coating for variety of substrates. Coatings can be used on metals, masonry, textiles, paper, and glass, and have superior hardness and flexibility, strong resistance to chemicals fire, and weather.

  2. Investigation on anti-corrosion property of nano-TiO2 fluoro-carbon coatings

    NASA Astrophysics Data System (ADS)

    Qi, Yu-hong; Zhang, Zhan-ping; Wang, Li-li; Du, Xue-peng

    2009-07-01

    To meet the need of long-term anticorrosive protection of steel, a heavy-duty anticorrosive coating systems was developed with Fluorocarbon top paint which was modified by nano-TiO2. The corrosive characteristics of low carbon steel coated with the system were investigated in seawater by the exposition tests and Electrochemical Impedance Spectroscopy (EIS). The results show that the protective system with fluorocarbon top coating modified by nano-TiO2 has much better endurance than the reference system with fluorocarbon top coating not modified by nano-TiO2. There isn't any rusting and blistering on the surface of former coating, the coating system remains in "GOOD" condition. But some rusting and blistering were found on the surface of reference coating. EIS results indicated that the impedance of the nano-coating system decreases much less than that of the reference one. The nano-coating system is hopeful to meet the need of new coatings standard and to provide a target useful coating life of 15 years for ship's ballast.

  3. Adhesion of metals to spin-coated fluorocarbon polymer films

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Kil; Chang, Chin-An; Schrott, A. G.

    1990-01-01

    Adhesion between metals and fluorocarbon polymer films has been studied for Cu, Cr, Ti, Al, and Au on polytetrafluoroethylene (PTFE) and tetrafluoroethylene-hexafluoropropylene copolymer (FEP) films. Polymer films were applied on the Cr/SiO2 /Si substrate by spinning the aqueous dispersions of the polymer resin particles, followed by thermal curing. Strips of different metals were deposited on the polymers, and adhesion was measured at 90° peel test. The peel strengths were invariably higher for the metals on FEP than those of the corresponding metals on PTFE. Among the metals, Ti showed the highest peel strength for both polymers, followed by Cr and Al, with Cu and Au being the lowest. The peel strengths of Ti, Cr, and Cu on FEP are 85, 45, and 12 g/mm, respectively, and the corresponding ones on PTFE are 23, 5, and 2 g/mm, respectively. X-ray photoelectron spectroscopic analysis shows that the metal-polymer bonding involves the metal-carbon interactions. The strongest interaction is observed for Ti with the polymers, forming Ti carbidelike bonds. Cr also shows strong interaction with the two polymers, but to a lesser degree compared with Ti. Only a weak bonding is shown for Cu. The difference in peel strengths among the metals shows a correlation with the difference in electronegativities between the metals and carbon. Little contribution to the observed peel strengths is seen from the surface morphological analysis of the untreated polymers.

  4. Fluorocarbon nano-coating of polyester fabrics by atmospheric air plasma with aerosol

    NASA Astrophysics Data System (ADS)

    Leroux, F.; Campagne, C.; Perwuelz, A.; Gengembre, L.

    2008-04-01

    A fluorocarbon coating was deposited on polyester (PET) woven fabric using pulse discharge plasma treatment by injecting a fluoropolymer directly into the plasma dielectric barrier discharge. The objective of the treatment was to improve the hydrophobic properties as well as the repellent behaviour of the polyester fabric. Plasma treatment conditions were optimised to obtain optimal hydrophobic properties which were evaluated using water contact angle measurement as well as spray-test method at the polyester fabric surface. The study showed that adhesion of the fluoropolymer to the woven PET was greatly enhanced by the air plasma treatment. X-ray photoemission spectroscopy (XPS) analyses revealed chemical surface modifications occurring after the plasma treatments.

  5. Preparation of transparent fluorocarbon/TiO2-SiO2 composite coating with improved self-cleaning performance and anti-aging property

    NASA Astrophysics Data System (ADS)

    Zhou, Jianping; Tan, Zhongyuan; Liu, Zhilei; Jing, Mengmeng; Liu, Wenjie; Fu, Wanli

    2017-02-01

    This work reports a facile method to fabricate transparent self-cleaning fluorocarbon coatings filled by semicrystalline colloidal particles of TiO2-SiO2 composite oxide presenting a particle size ranging from 6 to 10 nm. Anatase-TiO2 crystallites were successfully obtained after microwave heating treatment of the TiO2-SiO2 colloidal particles as confirmed by XRD, TEM and FTIR measurements. The fluorocarbon/TiO2-SiO2 composite coatings exhibited a superior hydrophilicity and an improved photocatalytic activity in contrast to the TiO2-filled coatings. In particular, a water contact angle (WCA) value of 4.5° and a decolorization ratio relative to methyl orange as high as 96.0% were achieved for the composite coatings containing 1.5 wt% of TiO2-SiO2 colloidal particles. The results of the anti-soiling experiments indicated that the fluorocarbon/TiO2-SiO2 composite coatings exhibited a prominent self-cleaning performance, while the accelerated aging experiments revealed that the fluorocarbon/TiO2-SiO2 composite coatings were highly stable toward UV irradiation when compared to the TiO2-filled fluorocarbon coatings. These findings indicated that the fluorocarbon/TiO2-SiO2 composite coatings could be a very attractive solution for many practical areas, especially for outdoor applications.

  6. Light-responsive nanoparticles with wettability changing from hydrophobicity to hydrophilicity and their application towards highly hydrophilic fluorocarbon coatings

    NASA Astrophysics Data System (ADS)

    Lin, Baozhong; Zhou, Shuxue

    2015-12-01

    Novel functional silica nanoparticles (SiO2-NBS-F) with irreversible light-responsive wettability were prepared by grafting of a light-responsive silane coupling agent (NBS) and further bonding with hydrophobic segments via a click reaction. The NBS was synthesized using an o-nitrobenzyl alcohol derivative of the photolabile protecting group. The SiO2-NBS-F nanoparticles exhibited considerable change of wettability from near-superhydrophobicity to near-superhydrophilicity after UV irradiation. The changing mechanism of wettability was confirmed by UV-Vis absorption spectra and X-ray photoelectron spectra. The SiO2-NBS-F nanoparticles were incorporated into fluorocarbon FEVE coatings by simple mixing. The nanoparticles occurred at the surface of the dried coatings even though their content was as low as 5 wt%, being due to their low surface free energy. The wettability of the SiO2-NBS-F filled FEVE coatings could transform from hydrophobicity (WCA 106.4°) to hydrophilicity (WCA 33.3°) after UV irradiation. It demonstrates that SiO2-NBS-F nanoparticles are useful to acquire highly hydrophilic surface for organic coatings.

  7. The performance of aminoalkyl/fluorocarbon/hydrocarbon-modified xerogel coatings against the marine alga Ectocarpus crouaniorum: relative roles of surface energy and charge.

    PubMed

    Evariste, Emmanuelle; Gatley, Caitlyn M; Detty, Michael R; Callow, Maureen E; Callow, James A

    2013-01-01

    The effect of a series of xerogel coatings modified with aminoalkyl/fluorocarbon/hydrocarbon groups on the adhesion of a new test species, the filamentous brown alga Ectocarpus crouaniorum, has been explored, and compared with the green alga Ulva linza. The results showed that E. crouaniorum adhered weakly to the less polar, low wettability coatings in the series, but stronger adhesion was shown on polar, higher surface energy coatings containing aminoalkyl groups. The results from a separate series of coatings tuned to have similar surface energies and polarities after immersion in artificial seawater (ASW), but widely different surface charges, demonstrated that surface charge was more important than surface energy and polarity in determining the adhesion strength of both E. crouaniorum and U. linza on xerogel coatings. No correlation was found between adhesion and contact angle hysteresis. X-ray photoelectron spectroscopy analysis of samples after immersion in ASW confirmed the presence of charged ammonium groups on the surface of the aminoalkylated coatings.

  8. Hydrogen Permeation Resistant Coatings

    SciTech Connect

    KORINKO, PAUL; ADAMS, THAD; CREECH, GREGGORY

    2005-06-15

    As the National Hydrogen Economy continues to develop and evolve the need for structural materials that can resist hydrogen assisted degradation will become critical. To date austenitic stainless steel materials have been shown to be mildly susceptible to hydrogen attack which results in lower mechanical and fracture strengths. As a result, hydrogen permeation barrier coatings may be applied to these ferrous alloys to retard hydrogen ingress. Hydrogen is known to be very mobile in materials of construction. In this study, the permeation resistance of bare stainless steel samples and coated stainless steel samples was tested. The permeation resistance was measured using a modular permeation rig using a pressure rise technique. The coating microstructure and permeation results will be discussed in this document as will some additional testing.

  9. Erosion resistant coatings

    NASA Technical Reports Server (NTRS)

    Falco, L.; Cushini, A.

    1981-01-01

    Apparatus for measuring the resistance of materials to erosion is examined and a scheme for standardization of the test parameters is described. Current materials being used for protecting aircraft parts from erosion are surveyed, their chief characteristics being given. The superior properties of urethane coatings are pointed out. The complete cycle for painting areas subject to erosion is described.

  10. Improved fire-resistant coatings

    NASA Technical Reports Server (NTRS)

    Hutt, J. B.; Stuart, J. W.

    1971-01-01

    Water-base coatings containing potassium silicate show improvement in areas of quick air-drying, crack, craze, and abrasion resistance, adherence, and leach resistance. Coatings are useful as thermal-barrier layers in furnaces, and as general purpose fire resistant surfaces where vapor impermeability is not a requirement.

  11. Corrosion resistant coating

    DOEpatents

    Wrobleski, Debra A.; Benicewicz, Brian C.; Thompson, Karen G.; Bryan, Coleman J.

    1997-01-01

    A method of protecting a metal substrate from corrosion including coating a metal substrate of, e.g., steel, iron or aluminum, with a conductive polymer layer of, e.g., polyaniline, coating upon said metal substrate, and coating the conductive polymer-coated metal substrate with a layer of a topcoat upon the conductive polymer coating layer, is provided, together with the resultant coated article from said method.

  12. Corrosion resistant coating

    DOEpatents

    Wrobleski, D.A.; Benicewicz, B.C.; Thompson, K.G.; Bryan, C.J.

    1997-08-19

    A method of protecting a metal substrate from corrosion including coating a metal substrate of, e.g., steel, iron or aluminum, with a conductive polymer layer of, e.g., polyaniline, coating upon said metal substrate, and coating the conductive polymer-coated metal substrate with a layer of a topcoat upon the conductive polymer coating layer, is provided, together with the resultant coated article from said method.

  13. PRODUCTION OF FLUOROCARBONS

    DOEpatents

    Sarsfield, N.F.

    1949-06-21

    This patent pertains to a process for recovering fluorocarbons from a liquid mixture of hydrocarbons with partially and completely fluorinated products thereof. It consists of contacting the mxture in the cold with a liquid which is a solvent for the hydrocarbons and which is a nonsolvent for the fluorocarbons, extracting the hydrocarbons, separating the fluorocarbon-containing layer from the solvent-containing layer, and submitting the fluorocarbon layer to fractlonal distillation, to isolate the desired fluorocarbon fraction. Suitable solvents wnich may be used in the process include the lower aliphatic alcohols, and the lower aliphatic ketones.

  14. Coatings for improved corrosion resistance

    SciTech Connect

    Natesan, K.

    1992-05-01

    Several coating approaches are being developed to resist attack in coal-fired environments and thereby minimize corrosion of underlying substrate alloys and extend the time for onset of breakaway corrosion. In general, coating systems can be classified as either diffusion or overlay type, which are distinguished principally by the method of deposition and the structure of the resultant coating-substrate bond. The coating techniques examined are pack cementation, electrospark deposition, physical and chemical vapor deposition, plasma spray, and ion implantation. In addition, ceramic coatings are used in some applications.

  15. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  16. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2013-11-12

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  17. Development of a special purpose spacecraft interior coating. Phase 2. [fire resistant fluoropolymer coating

    NASA Technical Reports Server (NTRS)

    Bartoszek, E. J.; Christofas, A.; Nannelli, P.

    1977-01-01

    Numerous acrylic and epoxy modifiers for the fluorocarbon latex resin base were investigated. Optimum coatings were developed by modifying the fluorocarbon latex with an epoxy acrylic resin system. In addition, a number of other formulations, containing hard acrylics as modifiers, displayed attractive properties and potential for further improvements. The preferred formulations dried to touch in about one hour and were fully dried in about twenty four hours under normal room temperature and humidity conditions. In addition to physical and mechanical properties either comparable or superior to those of commercial solvent base polyurethane or polyester coatings, the preferred compositions meet the flammability and offgassing requirements specified by NASA.

  18. Corrosion-resistant coating development

    SciTech Connect

    Stinton, D.P.; Kupp, D.M.; Martin, R.L.

    1997-12-01

    SiC-based heat exchangers have been identified as the prime candidate material for use as heat exchangers in advanced combined cycle power plants. Unfortunately, hot corrosion of the SiC-based materials created by alkali metal salts present in the combustion gases dictates the need for corrosion-resistant coatings. The well-documented corrosion resistance of CS-50 combined with its low (and tailorable) coefficient of thermal expansion and low modulus makes CS-50 an ideal candidate for this application. Coatings produced by gelcasting and traditional particulate processing have been evaluated.

  19. Corrosion resistant coating

    NASA Technical Reports Server (NTRS)

    Khanna, S. K.; Thakoor, A. P.; Williams, R. M. (Inventor)

    1985-01-01

    A method of coating a substrate with an amorphous metal is described. A solid piece of the metal is bombarded with ions of an inert gas in the presence of a magnetic field to provide a vapor of the metal which is deposited on the substrate at a sufficiently low gas pressure so that there is formed on the substrate a thin, uniformly thick, essentially pinhole-free film of the metal.

  20. A robust superhydrophobic PVDF composite coating with wear/corrosion-resistance properties

    NASA Astrophysics Data System (ADS)

    Wang, Huaiyuan; Liu, Zhanjian; Wang, Enqun; Yuan, Ruixia; Gao, Dong; Zhang, Xiguang; Zhu, Yanji

    2015-03-01

    A robust wear/corrosion-resistant superhydrophobic polyvinylidene fluoride (PVDF)/fluorinated ethylene propylene (FEP)/carbon nanofibers (CNFs) composite coating with a water contact angle (WCA) of 164 ± 1.5° and a slide angle of 5 ± 0.2° has been fabricated through the combination of chemical etching and spraying technique. The WCA of the coating still maintains 141 ± 1.2° after 10,000 times rubbing due to the designed internal nano/micro-structure and the slide angle increases from 5 ± 0.2° to 20 ± 0.5°. The prepared coating also demonstrates excellent corrosion-resistance property under strongly acidic or alkaline conditions for 15 days. The wear-resistance of the superhydrophobic coating is approximately 5 times higher than the pure PVDF coating and commercial fluorocarbon coating. These excellent mechanical properties are attributed to the new groups of Cdbnd C and Csbnd C by dehydrofluorination of PVDF and the new β-phase of PVDF by recrystallization of the α-phase. Furthermore, the enhanced adhesive ability of the coating corresponds with Grade 1 according to GB/T9286, mainly because that the interaction force among PVDF macromolecules can be intensified by chemical cross-linking and the hydroxyl groups formed on the surface of the aluminum plate by etching. It is believed that this robust multifunctional superhydrophobic coating may have the potential values in large-scale application.

  1. Tunable resistance coatings

    DOEpatents

    Elam, Jeffrey W.; Mane, Anil U.

    2015-08-11

    A method and article of manufacture of intermixed tunable resistance composite materials containing at least one of W:Al.sub.2O.sub.3, Mo:Al.sub.2O.sub.3 or M:Al.sub.2O.sub.3 where M is a conducting compound containing either W or Mo. A conducting material and an insulating material are deposited by such methods as ALD or CVD to construct composites with intermixed materials which do not have structure or properties like their bulk counterparts.

  2. Fluorocarbon nanodrops as acoustic temperature probes.

    PubMed

    Mountford, Paul A; Smith, William S; Borden, Mark A

    2015-10-06

    This work investigated the use of superheated fluorocarbon nanodrops for ultrasound thermal imaging and the use of mixed fluorocarbons for tuning thermal and acoustic thresholds for vaporization. Droplets were fabricated by condensing phospholipid-coated microbubbles containing C3F8 and C4F10 mixed at various molar ratios. Vaporization temperatures first were measured in a closed system by optical transmission following either isothermal pressure release or isobaric heating. The vaporization temperature was found to depend linearly on the percentage of C4F10 in the droplet core, indicating excellent tunability under these fluorocarbon-saturated conditions. Vaporization temperatures were then measured in an open system using contrast-enhanced ultrasound imaging, where it was found that the mixed droplets behaved like pure C4F10 drops. Additionally, the critical mechanical index for vaporization was measured at the limits of therapeutic hyperthermia (37 and 60 °C), and again the mixed droplets were found to behave like pure C4F10 drops. These results suggested that C3F8 preferentially dissolves out of the droplet core in open systems, as shown by a simple mass transfer model of multicomponent droplet dissolution. Finally, proof-of-concept was shown that pure C4F10 nanodrops can be used as an acoustic temperature probe. Overall, these results not only demonstrate the potential of superheated fluorocarbon emulsions for sonothermetry but also point to the limits of tunability for fluorocarbon mixtures owing to preferential release of the more soluble species to the atmosphere.

  3. Impact-Resistant Ceramic Coating

    NASA Technical Reports Server (NTRS)

    Wheeler, W. H.; Creedon, J. F.; Izu, Y. D.

    1986-01-01

    Refractory fibers more than double strength of coating. Impact strengths of ceramic coatings increase with increasing whisker content. Silicon carbide whiskers clearly produce largest increase, and improvement grows even more with high-temperature sintering. Coating also improves thermal and mechanical properties of electromagnetic components, mirrors, furnace linings, and ceramic parts of advanced internal-combustion engines.

  4. Coated Aluminized Film Resists Corrosion

    NASA Technical Reports Server (NTRS)

    Rockoff, H. J.

    1982-01-01

    Commercially available corrosion-protection coating allows less costly metals - aluminum in particular used in heat-reflecting films for thermal barriers. Previously, such films had to incorporate gold as reflective layer to withstand humidity, moisture, and salt spray without corroding. This protective coating prevents corrosion of metalized films during evironmental exposure yet remains flexible, thermally stable and clear.

  5. Conformal chemically resistant coatings for microflow devices

    DOEpatents

    Folta, James A.; Zdeblick, Mark

    2003-05-13

    A process for coating the inside surfaces of silicon microflow devices, such as electrophoresis microchannels, with a low-stress, conformal (uniform) silicon nitride film which has the ability to uniformly coat deeply-recessed cavities with, for example, aspect ratios of up to 40:1 or higher. The silicon nitride coating allows extended exposure to caustic solutions. The coating enables a microflow device fabricated in silicon to be resistant to all classes of chemicals: acids, bases, and solvents. The process involves low-pressure (vacuum) chemical vapor deposition. The ultra-low-stress silicon nitride deposition process allows 1-2 .mu.m thick films without cracks, and so enables extended chemical protection of a silicon microflow device against caustics for up to 1 year. Tests have demonstrated the resistance of the films to caustic solutions at both ambient and elevated temperatures to 65.degree. C.

  6. Versatile Coating

    NASA Technical Reports Server (NTRS)

    1990-01-01

    A radome at Logan Airport and a large parabolic antenna at the Wang Building in Massachusetts are protected from weather, corrosion and ultraviolet radiation by a coating, specially designed for antennas and radomes, known as CRC Weathertite 6000. The CRC 6000 line that emerged from Boyd Coatings Research Co., Inc. is a solid dispersion of fluorocarbon polymer and polyurethane that yields a tough, durable film with superior ultraviolet resistance and the ability to repel water and ice over a long term. Additionally, it provides resistance to corrosion, abrasion, chemical attacks and impacts. Material can be used on a variety of substrates, such as fiberglass, wood, plastic and concrete in addition to steel and aluminum. In addition Boyd Coatings sees CRC 6000 applicability as an anti-icing system coated on the leading edge of aircraft wings.

  7. Corrosion-resistant ceramic thermal barrier coating

    NASA Technical Reports Server (NTRS)

    Hodge, P. E.; Levine, S. R.; Miller, R. A.

    1980-01-01

    Two-layer thermal barrier coating, consisting of metal-CrA1Y bond coating and calcium silicate ceramic outer layer, greatly improves resistance of turbine parts to hot corrosion from fuel and air impurities. Both layers can be plasma sprayed, and ceramic layer may be polished to reduce frictional losses. Ceramic provides thermal barrier, so parts operate cooler metal temperatures, coolant flow can be reduced, or gas temperatures increased. Lower grade fuels also can be used.

  8. Wear Resistant Amorphous and Nanocomposite Steel Coatings

    SciTech Connect

    Branagan, Daniel James; Swank, William David; Haggard, Delon C; Fincke, James Russell; Sordelet, D.

    2001-10-01

    In this article, amorphous and nanocomposite thermally deposited steel coatings have been formed by using both plasma and high-velocity oxy-fuel (HVOF) spraying techniques. This was accomplished by developing a specialized iron-based composition with a low critical cooling rate (?104 K/s) for metallic glass formation, processing the alloy by inert gas atomization to form micron-sized amorphous spherical powders, and then spraying the classified powder to form coatings. A primarily amorphous structure was formed in the as-sprayed coatings, independent of coating thickness. After a heat treatment above the crystallization temperature (568°C), the structure of the coatings self-assembled (i.e., devitrified) into a multiphase nanocomposite microstructure with 75 to 125 nm grains containing a distribution of 20 nm second-phase grain-boundary precipitates. Vickers microhardness testing revealed that the amorphous coatings were very hard (10.2 to 10.7 GPa), with further increases in hardness after devitrification (11.4 to 12.8 GPa). The wear characteristics of the amorphous and nanocomposite coatings were determined using both two-body pin-on-disk and three-body rubber wheel wet-slurry sand tests. The results indicate that the amorphous and nanocomposite steel coatings are candidates for a wide variety of wear-resistant applications.

  9. Spraylon fluorocarbon encapsulation for silicon solar cell arrays

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A development program was performed for evaluating, modifying, and optimizing the Lockheed formulated liquid transparent filmforming Spraylon fluorocarbon protective coating for silicon solar cells and modules. The program objectives were designed to meet the requirements of the low-cost automated solar cell array fabrication process. As part of the study, a computer program was used to establish the limits of the safe working stress in the coated silicon solar cell array system under severe thermal shock.

  10. Oxidation corrosion resistant superalloys and coatings

    NASA Technical Reports Server (NTRS)

    Jackson, Melvin R. (Inventor); Rairden, III, John R. (Inventor)

    1978-01-01

    An article of manufacture having improved high temperature oxidation and corrosion resistance comprising: (a) a superalloy substrate containing a carbide reinforcing phase, and (b) a coating consisting of chromium, aluminum, carbon, at least one element selected from iron, cobalt or nickel, and optionally an element selected from yttrium or the rare earth elements.

  11. Oxidation corrosion resistant superalloys and coatings

    NASA Technical Reports Server (NTRS)

    Jackson, Melvin R. (Inventor); Rairden, III, John R. (Inventor)

    1980-01-01

    An article of manufacture having improved high temperature oxidation and corrosion resistance comprising: (a) a superalloy substrate containing a carbide reinforcing phase, and (b) a coating consisting of chromium, aluminum, carbon, at least one element selected from iron, cobalt or nickel, and optionally an element selected from yttrium or the rare earth elements.

  12. Antisoiling Coatings for Solar-Energy Devices

    NASA Technical Reports Server (NTRS)

    Cuddihy, E. F.; Willis, P.

    1986-01-01

    Fluorocarbons resist formation of adherent deposits. Promising coating materials reduce soiling of solar photovoltaic modules and possibly solar thermal collectors. Contaminating layers of various degrees of adherence form on surfaces of devices, partially blocking incident solar energy, reducing output power. Loose soil deposits during dry periods but washed off by rain. New coatings help prevent formation of more-adherent, chemically and physically bonded layers rain alone cannot wash away.

  13. Thermal barrier coating resistant to sintering

    DOEpatents

    Subramanian, Ramesh; Seth, Brij B.

    2004-06-29

    A device (10) is made, having a ceramic thermal barrier coating layer (16) characterized by a microstructure having gaps (18) with a sintering inhibiting material (22) disposed on the columns (20) within the gaps (18). The sintering resistant material (22) is stable over the range of operating temperatures of the device (10), is not soluble with the underlying ceramic layer (16) and is applied by a process that is not an electron beam physical vapor deposition process.

  14. Thermal barrier coating resistant to sintering

    DOEpatents

    Subramanian, Ramesh; Sabol, Stephen M.

    2001-01-01

    A device (10) having a ceramic thermal barrier coating layer (16) characterized by a microstructure having gaps (18) with a sintering inhibiting material (22) disposed on the columns (20) within the gaps (18). The sintering resistant material (22) is stable over the range of operating temperatures of the device (10) and is not soluble with the underlying ceramic layer (16). For a YSZ ceramic layer (16) the sintering resistant layer (22) may preferably be aluminum oxide or yttrium aluminum oxide, deposited as a continuous layer or as nodules.

  15. Chromate-free corrosion resistant conversion coatings for aluminum

    SciTech Connect

    Buchheit, R.G. ); Stoner, G.E. . Dept. of Materials Science and Engineering)

    1993-01-01

    We have developed a method for generating chromate-free corrosion resistant coatings on aluminum alloys using a process procedurally similar to standard chromate conversion. These coatings provide good corrosion resistance on 6061-T6 and 1100 A1 under salt spray testing conditions. The resistance of the new coating is comparable to that of chromate conversion coatings in four point probe tests, but higher when a mercury probe technique is used. Initial tests of paint adhesion, and under paint corrosion resistance are promising. Primary advantage of this new process is that no hazardous chemicals are used or produced during the coating operation.

  16. Chromate-free corrosion resistant conversion coatings for aluminum

    SciTech Connect

    Buchheit, R.G.; Stoner, G.E.

    1993-03-01

    We have developed a method for generating chromate-free corrosion resistant coatings on aluminum alloys using a process procedurally similar to standard chromate conversion. These coatings provide good corrosion resistance on 6061-T6 and 1100 A1 under salt spray testing conditions. The resistance of the new coating is comparable to that of chromate conversion coatings in four point probe tests, but higher when a mercury probe technique is used. Initial tests of paint adhesion, and under paint corrosion resistance are promising. Primary advantage of this new process is that no hazardous chemicals are used or produced during the coating operation.

  17. Spraylon fluorocarbon encapsulation for silicon solar cell arrays, phase 3

    NASA Technical Reports Server (NTRS)

    Naes, L. G.

    1978-01-01

    The liquid transparent film-forming, fluorocarbon, Spraylon, a protective coating for terrestrial solar cell modules was evaluated. Two modules were completed and field tested. Problems developed early in the field testing which led to the shortened test period, specifically, lifting of the antireflection coating, followed in some areas by complete film delamination. It is believed that although these problems were certainly induced by the presence of the SPRAYLON film, they were not failures of the material per se. Instead, assembly procedures, module design, and cell coating quality should be evaluated to determine cause of failure.

  18. Biomimetic fluorocarbon surfactant polymers reduce platelet adhesion on PTFE/ePTFE surfaces.

    PubMed

    Wang, Shuwu; Gupta, Anirban Sen; Sagnella, Sharon; Barendt, Pamela M; Kottke-Marchant, Kandice; Marchant, Roger E

    2009-01-01

    We describe a series of fluorocarbon surfactant polymers designed as surface-modifying agents for improving the thrombogenicity of ePTFE vascular graft materials by the reduction of platelet adhesion. The surfactant polymers consist of a poly(vinyl amine) backbone with pendent dextran and perfluoroundecanoyl branches. Surface modification is accomplished by a simple dip-coating process in which surfactant polymers undergo spontaneous surface-induced adsorption and assembly on PTFE/ePTFE surface. The adhesion stability of the surfactant polymer on PTFE was examined under dynamic shear conditions in PBS and human whole blood with a rotating disk system. Fluorocarbon surfactant polymer coatings with three different dextran to perfluorocarbon ratios (1:0.5, 1:1 and 1:2) were compared in the context of platelet adhesion on PTFE/ePTFE surface under dynamic flow conditions. Suppression of platelet adhesion was achieved for all three coated surfaces over the shear-stress range of 0-75 dyn/cm2 in platelet-rich plasma (PRP) or human whole blood. The effectiveness depended on the surfactant polymer composition such that platelet adhesion on coated surfaces decreased significantly with increasing fluorocarbon branch density at 0 dyn/cm2. Our results suggest that fluorocarbon surfactant polymers can effectively suppress platelet adhesion and demonstrate the potential application of the fluorocarbon surfactant polymers as non-thrombogenic coatings for ePTFE vascular grafts.

  19. Biomimetic Fluorocarbon Surfactant Polymers Reduce Platelet Adhesion on PTFE/ePTFE Surfaces

    PubMed Central

    Wang, Shuwu; Gupta, Anirban Sen; Sagnella, Sharon; Barendt, Pamela M.; Kottke-Marchant, Kandice; Marchant, Roger E.

    2010-01-01

    We describe a series of fluorocarbon surfactant polymers designed as surface-modifying agents for improving the thrombogenicity of ePTFE vascular graft materials by the reduction of platelet adhesion. The surfactant polymers consist of a poly(vinyl amine) backbone with pendent dextran and perfluoroundecanoyl branches. Surface modification is accomplished by a simple dip-coating process in which surfactant polymers undergo spontaneous surface-induced adsorption and assembly on PTFE/ePTFE surface. The adhesion stability of the surfactant polymer on PTFE was examined under dynamic shear conditions in PBS and human whole blood with a rotating disk system. Fluorocarbon surfactant polymer coatings with three different dextran to perfluorocarbon ratios (1:0.5, 1:1 and 1:2) were compared in the context of platelet adhesion on PTFE/ePTFE surface under dynamic flow conditions. Suppression of platelet adhesion was achieved for all three coated surfaces over the shear-stress range of 0–75 dyn/cm2 in platelet-rich plasma (PRP) or human whole blood. The effectiveness depended on the surfactant polymer composition such that platelet adhesion on coated surfaces decreased significantly with increasing fluorocarbon branch density at 0 dyn/cm2. Our results suggest that fluorocarbon surfactant polymers can effectively suppress platelet adhesion and demonstrate the potential application of the fluorocarbon surfactant polymers as non-thrombogenic coatings for ePTFE vascular grafts. PMID:19323880

  20. Metals plated on fluorocarbon polymers

    NASA Technical Reports Server (NTRS)

    Ford, H.; Krasinsky, J. B.; Vango, S. P.

    1964-01-01

    Electroplating lead on fluorocarbon polymer parts is accomplished by etching the parts to be plated with sodium, followed by successive depositions of silver and lead from ultrasonically agitated plating solutions. Metals other than lead may be electroplated on the silvered parts.

  1. Molecular origins of fluorocarbon hydrophobicity

    PubMed Central

    Dalvi, Vishwanath H.; Rossky, Peter J.

    2010-01-01

    We have undertaken atomistic molecular simulations to systematically determine the structural contributions to the hydrophobicity of fluorinated solutes and surfaces compared to the corresponding hydrocarbon, yielding a unified explanation for these phenomena. We have transformed a short chain alkane, n-octane, to n-perfluorooctane in stages. The free-energy changes and the entropic components calculated for each transformation stage yield considerable insight into the relevant physics. To evaluate the effect of a surface, we have also conducted contact-angle simulations of water on self-assembled monolayers of hydrocarbon and fluorocarbon thiols. Our results, which are consistent with experimental observations, indicate that the hydrophobicity of the fluorocarbon, whether the interaction with water is as solute or as surface, is due to its “fatness.” In solution, the extra work of cavity formation to accommodate a fluorocarbon, compared to a hydrocarbon, is not offset by enhanced energetic interactions with water. The enhanced hydrophobicity of fluorinated surfaces arises because fluorocarbons pack less densely on surfaces leading to poorer van der Waals interactions with water. We find that interaction of water with a hydrophobic solute/surface is primarily a function of van der Waals interactions and is substantially independent of electrostatic interactions. This independence is primarily due to the strong tendency of water at room temperature to maintain its hydrogen bonding network structure at an interface lacking hydrophilic sites. PMID:20643968

  2. A conformal oxidation-resistant, plasma-polymerized coating

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Wydeven, Theodore; Lerner, Narcinda R.

    1991-01-01

    A comparative study was made of the surface recession (etching) of thin films of plasma polymerized tetrafluoro ethylene (PPTFE), polytetrafluoro ethylene (PTFE), and ion-beam sputter deposited polytetrafluoro ethylene (SPTFE) exposed to ground-state atomic oxygen downstream from a nonequilibrium radio-frequency O2 plasma. At 22 C, the etch rates for PTFE, SPTFE, and PPTFE were in the ratio of 8.7:1.8:1.0. A thin, conformal coating of PPTFE (etch rate of 0.3 nm/h at 22 C) was found to protect an underlying cast film of a reactive polymer, cis-1,4 polybutadiene, against ground-state atomic oxygen attack for the time required to fully etch away the PPTFE coating. From ESCA analysis, PTFE exhibited only minor surface oxidation (uptake of 0.5 atom percent O) upon etching, its F/C ratio decreasing slightly from 2.00 to 1.97; PPTFE exhibited considerable surface oxidation (uptake of 5.9 atom percent O) intermediate between those of PTFE and PPTFE, with a decrease in F/C ratio from 1.73 to 1.67. A plasma-polymerized fluorocarbon coating such as PPTFE might be useful for space applications to protect polymers that are vulnerable to oxidation or degradation by oxygen atoms.

  3. Demonstrating a Lack of Reactivity Using a Teflon-Coated Pan.

    ERIC Educational Resources Information Center

    Richmond, Thomas G.

    1995-01-01

    Illustrates the chemical resistance of polytetrafluoroethene to mineral acids using an ordinary Teflon-coated frying pan. The demonstration can also be used to lead to a discussion of the long lifetimes of fluorocarbons and chlorofluorocarbons in the atmosphere and their roles in the breakdown of the ozone layer. (AIM)

  4. Erosion / Corrosion Resistant Coatings for Compressor Airfoils

    DTIC Science & Technology

    2012-08-29

    2012 2. REPORT TYPE 3 . DATES COVERED 00-00-2012 to 00-00-2012 4. TITLE AND SUBTITLE Erosion / Corrosion Resistant Coatings for Compressor...driver • DoD consumes ≈ $13B in aviation fuel annually • Eroded engines emit 10 to 25% greater pollutants 2 3 Erosive media GAS TURBINE ENGINE...AGT1500 for M1A Tank RTM322 for Merlin Arriel for LUH Gnome for Sea King CF34 for E170     5 T64 for H-53  HPW3000 CFM56 for

  5. Evaluation of Erosion Resistance of Advanced Turbine Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Kuczmarski, Maria A.; Miller, Robert A.; Cuy, Michael D.

    2007-01-01

    The erosion resistant turbine thermal barrier coating system is critical to aircraft engine performance and durability. By demonstrating advanced turbine material testing capabilities, we will be able to facilitate the critical turbine coating and subcomponent development and help establish advanced erosion-resistant turbine airfoil thermal barrier coatings design tools. The objective of this work is to determine erosion resistance of advanced thermal barrier coating systems under simulated engine erosion and/or thermal gradient environments, validating advanced turbine airfoil thermal barrier coating systems based on nano-tetragonal phase toughening design approaches.

  6. Wear Resistant Amorphous and Nanocomposite Coatings

    SciTech Connect

    Racek, O

    2008-03-26

    Glass forming materials (critical cooling rate <10{sup 4}K.s{sup -1}) are promising for their high corrosion and wear resistance. During rapid cooling, the materials form an amorphous structure that transforms to nanocrystalline during a process of devitrification. High hardness (HV 1690) can be achieved through a controlled crystallization. Thermal spray process has been used to apply coatings, which preserves the amorphous/nanocomposite structure due to a high cooling rate of the feedstock particles during the impact on a substrate. Wear properties have been studied with respect to process conditions and feedstock material properties. Application specific properties such as sliding wear resistance have been correlated with laboratory tests based on instrumented indentation and scratch tests.

  7. Oxidation-Resistant Coating For Bipolar Lead/Acid Battery

    NASA Technical Reports Server (NTRS)

    Bolstad, James J.

    1993-01-01

    Cathode side of bipolar substrate coated with nonoxidizable conductive layer. Coating prepared as water slurry of aqueous dispersion of polyethylene copolymer plus such conductive fillers as tin oxide, titanium, tantalum, or tungsten oxide. Applied easily to substrate of polyethylene carbon plastic. As slurry dries, conductive, oxidation-resistant coating forms on positive side of substrate.

  8. Oxidation-resistant silicide coating applied to columbium alloy screen

    NASA Technical Reports Server (NTRS)

    Torgerson, R. T.

    1971-01-01

    Coated screens withstand temperature cycling in special transpiration-cooling systems and provide porous surface that is effective at temperatures well above those limiting superalloy screen efficiency. Thickness of coating depends on time, temperature and activator concentration. Coatings are uniform and resistant to thermal cycling.

  9. Porous alumina based ordered nanocomposite coating for wear resistance

    NASA Astrophysics Data System (ADS)

    Yadav, Arti; Muthukumar, M.; Bobji, M. S.

    2016-08-01

    Uniformly dispersed nanocomposite coating of aligned metallic nanowires in a matrix of amorphous alumina is fabricated by pulsed electrodeposition of copper into the pores of porous anodic alumina. Uniform deposition is obtained by controlling the geometry of the dendritic structure at the bottom of pores through stepwise voltage reduction followed by mild etching. The tribological behaviour of this nanocomposite coating is evaluated using a ball on flat reciprocating tribometer under the dry contact conditions. The nanocomposite coating has higher wear resistance compared to corresponding porous alumina coating. Wear resistant nanocomposite coating has wide applications especially in protecting the internal surfaces of aluminium internal combustion engines.

  10. Low friction and galling resistant coatings and processes for coating

    DOEpatents

    Johnson, Roger N.

    1987-01-01

    The present invention describes coating processes and the resultant coated articles for use in high temperature sodium environments, such as those found in liquid metal fast breeder reactors and their associated systems. The substrate to which the coating is applied may be either an iron base or nickel base alloy. The coating itself is applied to the substrate by electro-spark deposition techniques which result in metallurgical bonding between the coating and the substrate. One coating according to the present invention involves electro-spark depositing material from a cemented chromium carbide electrode and an aluminum electrode. Another coating according to the present invention involves electro-spark depositing material from a cemented chromium carbide electrode and a nickel-base hardfacing alloy electrode.

  11. Wear Resistant Nanostructured Multi-component Coatings

    NASA Astrophysics Data System (ADS)

    Urbahs, A.; Urbaha, M.; Savkovs, K.; Bogdanova, S.

    The authors offer the restoration technology of precision pair parts - valves, plungers and injectors of vehicle fuel pumps. The technology stipulates the creation of a special restoring wear-resistant coating on the basis of Ti-Al-N (titanium-aluminum-nitrogen) deposited by ion-plasma sputtering. The possibility of combining the methods of electric arc and magnetron sputtering, which arose as a result of the modification of the installation, makes it possible to partially reduce the drawbacks of both methods by simultaneously using their basic advantages. This technique, in particular, gave the opportunity to reduce the drop phase without reducing the efficiency of ion bombardment. In addition, the spectrum of materials being sputtered has been expanded and their quality has been improved.

  12. Thermal barrier coating resistant to sintering

    DOEpatents

    Subramanian, Ramesh; Seth, Brig B.

    2005-08-23

    A device (10) is made, having a ceramic thermal barrier coating layer (16) characterized by a microstructure having gaps (18) with a sintering inhibiting material (22) disposed on the columns (20) within the gaps (18). The sintering resistant material (22) is stable over the range of operating temperatures of the device (10), is not soluble with the underlying ceramic layer (16) and is applied by a process that is not an electron beam physical vapor deposition process. The sintering inhibiting material (22) has a morphology adapted to improve the functionality of the sintering inhibiting material (22), characterized as continuous, nodule, rivulet, grain, crack, flake and combinations thereof and being disposed within at least some of the vertical and horizontal gaps.

  13. Fluorinated diamond bonded in fluorocarbon resin

    DOEpatents

    Taylor, Gene W.

    1982-01-01

    By fluorinating diamond grit, the grit may be readily bonded into a fluorocarbon resin matrix. The matrix is formed by simple hot pressing techniques. Diamond grinding wheels may advantageously be manufactured using such a matrix. Teflon fluorocarbon resins are particularly well suited for using in forming the matrix.

  14. Hydroxyapatite/poly(epsilon-caprolactone) double coating on magnesium for enhanced corrosion resistance and coating flexibility.

    PubMed

    Jo, Ji-Hoon; Li, Yuanlong; Kim, Sae-Mi; Kim, Hyoun-Ee; Koh, Young-Hag

    2013-11-01

    Hydroxyapatite was deposited on pure magnesium (Mg) with a flexible poly(ε-caprolactone) interlayer to reduce the corrosion rate of Mg and enhance coating flexibility. The poly(ε-caprolactone) interlayer was uniformly coated on Mg by a spraying method, followed by hydroxyapatite deposition on the poly(ε-caprolactone) using an aerosol deposition method. In scanning electron microscopy observations, inorganic/organic composite-like structure was observed between the hydroxyapatite and poly(ε-caprolactone) layers, resulting from the collisions of hydroxyapatite particles into the poly(ε-caprolactone) matrix at the initial stage of the aerosol deposition. The corrosion resistance of the coated Mg was examined using potentiodynamic polarization tests. The hydroxyapatite/poly(ε-caprolactone) double coating remarkably improved the corrosion resistance of Mg in Hank's solution. In the in vitro cell tests, the coated Mg showed better cell adhesion compared with the bare Mg due to the reduced corrosion rate and enhanced biocompatibility. The stability and flexibility of hydroxyapatite/poly(ε-caprolactone) double coating was investigated by scanning electron microscopy inspections after the coated Mg was deformed. The hydroxyapatite coating on the poly(ε-caprolactone) interlayer revealed enhanced coating stability and flexibility without cracking or delamination during bending and stretching compared with the hydroxyapatite single coating. These results demonstrated that the hydroxyapatite/poly(ε-caprolactone) double coating significantly improved the surface corrosion resistance of Mg and enhanced coating flexibility for use of Mg as a biodegradable implant.

  15. Wear and impact resistance of HVOF sprayedceramic matrix composites coating

    NASA Astrophysics Data System (ADS)

    Prawara, B.; Martides, E.; Priyono, B.; Ardy, H.; Rikardo, N.

    2016-02-01

    Ceramic coating has the mechanical properties of high hardness and it is well known for application on wear resistance, but on the other hand the resistance to impact load is low. Therefore its use is limited to applications that have no impact loading. The aim of this research was to obtain ceramic-metallic composite coating which has improved impact resistance compared to conventional ceramic coating. The high impact resistance of ceramic-metallic composite coating is obtained from dispersed metallic alloy phase in ceramic matrix. Ceramic Matrix Composites (CMC) powder with chrome carbide (Cr3C2) base and ceramic-metal NiAl-Al2O3 with various particle sizes as reinforced particle was deposited on mild steel substrate with High Velocity Oxygen Fuel (HVOF) thermal spray coating. Repeated impact test showed that reinforced metallic phase size influenced impact resistance of CMC coating. The ability of CMC coating to absorb impact energy has improved eight times and ten times compared with original Cr3C2 and hard chrome plating respectively. On the other hand the high temperature corrosion resistance of CMC coating showed up to 31 cycles of heating at 800°C and water quenching cooling.

  16. Hydrogen and Wear Resistant Nanolaminate Coatings

    SciTech Connect

    2009-02-01

    This factsheet describes a study that will develop the concept of superhard coatings based on alternating nanoscale layers of sputter-deposited coatings with anticipated hydrogen compatibility and low friction coefficients.

  17. Corrosion resistant coatings suitable for elevated temperature application

    DOEpatents

    Chan, Kwai S [San Antonio, TX; Cheruvu, Narayana Sastry [San Antonio, TX; Liang, Wuwei [Austin, TX

    2012-07-31

    The present invention relates to corrosion resistance coatings suitable for elevated temperature applications, which employ compositions of iron (Fe), chromium (Cr), nickel (Ni) and/or aluminum (Al). The compositions may be configured to regulate the diffusion of metals between a coating and a substrate, which may then influence coating performance, via the formation of an inter-diffusion barrier layer. The inter-diffusion barrier layer may comprise a face-centered cubic phase.

  18. Resistive coating for current conductors in cryogenic applications

    DOEpatents

    Hirayama, Chikara; Wagner, George R.

    1982-05-18

    This invention relates to a resistive or semiconducting coating for use on current conductors in cryogenic applications. This includes copper-clad superconductor wire, copper wire used for stabilizing superconductor magnets, and for hyperconductors. The coating is a film of cuprous sulfide (Cu.sub.2 S) that has been found not to degrade the properties of the conductors. It is very adherent to the respective conductors and satisfies the mechanical, thermal and electrical requirements of coatings for the conductors.

  19. Structural Transformations in heat resistant coatings containing rare earth elements

    NASA Astrophysics Data System (ADS)

    Afanasiev, N. I.; Lepakova, O. K.; Kosova, N. I.

    2016-01-01

    Degradation of two-layered coatings and ZhS6U alloy microstructure were studied during long-term processes of high temperature annealing and creeping. It was shown that yttrium and zirconium oxides are promising as protective coatings for heat resistant nickel based alloy.

  20. Resistance of dentin coating materials against abrasion by toothbrush.

    PubMed

    Gando, Iori; Ariyoshi, Meu; Ikeda, Masaomi; Sadr, Alireza; Nikaido, Toru; Tagami, Junji

    2013-01-01

    Thin-film coating of root dentin surface by all-in-one adhesives has been shown to be an effective option to prevent root surface caries. The purpose of this study was to investigate the wear resistance against toothbrush abrasion of two all-in-one coating materials; Shield Force (SF) and Hybrid Coat (HC). Bovine dentin surfaces were covered with one of the coating materials; SF or HC. After storage in water for 24 h, the testing surface was subjected to the toothbrush abrasion test up to 50,000 cycles either in water or toothpaste slurry. The remaining thickness of the coating material was measured using SEM. Toothpaste slurry significantly increased rate of tooth brush abrasion of the coating materials. While SF and HC wore at a similar pace under toothbrush abrasion, SF had a thicker coat and could protect dentin longer, up to 50,000 cycles.

  1. Final report of ''Fundamental Surface Reaction Mechanisms in Fluorocarbon Plasma-Based Processing''

    SciTech Connect

    Gottlieb S. Oehrlein; H. Anderson; J. Cecchi; D. Graves

    2004-09-21

    This report provides a summary of results obtained in research supported by contract ''Fundamental Surface Reaction Mechanisms in Fluorocarbon Plasma-Based Processing'' (Contract No. DE-FG0200ER54608). In this program we advanced significantly the scientific knowledge base on low pressure fluorocarbon plasmas used for patterning of dielectric films and for producing fluorocarbon coatings on substrates. We characterized important neutral and ionic gas phase species that are incident at the substrate, and the processes that occur at relevant surfaces in contact with the plasma. The work was performed through collaboration of research groups at three universities where significantly different, complementary tools for plasma and surface characterization, computer simulation of plasma and surface processes exist. Exchange of diagnostic tools and experimental verification of key results at collaborating institutions, both experimentally and by computer simulations, was an important component of the approach taken in this work.

  2. Sol-gel derived contamination resistant antireflective coatings

    NASA Astrophysics Data System (ADS)

    Shen, Jun; Liu, Yuan; Wu, Guangming; Zhou, Bin; Zhang, Zhihua; Zhu, Yumei

    2011-02-01

    Silica-based sol-gel antireflective (AR) optical coatings are critical components for high peak power laser systems. It is well known that water vapor and volatile organic compounds in both the laser bay and target bay environments will reduce the antireflective efficiency and laser-damage resistance of the sol-gel AR coating. In this study, alkylation with organosilanes in the vapor state was investigated. Sol-gel AR coatings were vapor-phase treated with hexamethyldisilazane (HMDS) and trimethylchlorosilane (TMCS) at room temperature, and the resulting post-treated sol-gel AR coatings were tested for their resistance to contamination by a series of volatile organic compounds. Contact angle measurements were taken to discern the degree of silanization. After the vapor treatment of sol-gel AR coatings with organosilanes, the spectral performance of the coatings were analyzed by spectrophotometer, both before and after the exposure to volatile organic compounds. It is found that the coatings treated with ammonia and HMDS show a better contamination resistant capability. After being contaminated 70 hours with hexane, the transmittance of the coatings presents no obvious decrease. And the vapor treatment produces an increase in their damage threshold at 1064 nm (10ns pulse width) as compared to untreated control samples.

  3. Sol-gel derived contamination resistant antireflective coatings

    NASA Astrophysics Data System (ADS)

    Shen, Jun; Liu, Yuan; Wu, Guangming; Zhou, Bin; Zhang, Zhihua; Zhu, Yumei

    2010-10-01

    Silica-based sol-gel antireflective (AR) optical coatings are critical components for high peak power laser systems. It is well known that water vapor and volatile organic compounds in both the laser bay and target bay environments will reduce the antireflective efficiency and laser-damage resistance of the sol-gel AR coating. In this study, alkylation with organosilanes in the vapor state was investigated. Sol-gel AR coatings were vapor-phase treated with hexamethyldisilazane (HMDS) and trimethylchlorosilane (TMCS) at room temperature, and the resulting post-treated sol-gel AR coatings were tested for their resistance to contamination by a series of volatile organic compounds. Contact angle measurements were taken to discern the degree of silanization. After the vapor treatment of sol-gel AR coatings with organosilanes, the spectral performance of the coatings were analyzed by spectrophotometer, both before and after the exposure to volatile organic compounds. It is found that the coatings treated with ammonia and HMDS show a better contamination resistant capability. After being contaminated 70 hours with hexane, the transmittance of the coatings presents no obvious decrease. And the vapor treatment produces an increase in their damage threshold at 1064 nm (10ns pulse width) as compared to untreated control samples.

  4. Theoretical analysis of thermal shock resistance of ceramic foam coatings

    NASA Astrophysics Data System (ADS)

    Zhang, Y. X.; Wang, B. L.

    2017-01-01

    Ceramic foams have a high resistance to corrosion and wear. They also have a good thermal insulation performance because of their high melting point and low thermal conductivity. The thermal shock resistance of a ceramic foam coating with an edge crack under a sudden temperature variation is investigated. The dynamic thermal stress fields in the ceramic foam coating are obtained. Using the superposition principle, the crack problem of the ceramic foam coating is reduced to the solution of a set of singular integral equations. Propagation of the edge crack is analyzed. Effects of the relative density and thermal properties of the ceramic foam and of crack length on the thermal shock resistance are identified. The results obtained can be useful in designing thermal protective ceramic materials for thermal barrier coatings.

  5. Optically transparent, scratch-resistant, diamond-like carbon coatings

    DOEpatents

    He, Xiao-Ming; Lee, Deok-Hyung; Nastasi, Michael A.; Walter, Kevin C.; Tuszewski, Michel G.

    2003-06-03

    A plasma-based method for the deposition of diamond-like carbon (DLC) coatings is described. The process uses a radio-frequency inductively coupled discharge to generate a plasma at relatively low gas pressures. The deposition process is environmentally friendly and scaleable to large areas, and components that have geometrically complicated surfaces can be processed. The method has been used to deposit adherent 100-400 nm thick DLC coatings on metals, glass, and polymers. These coatings are between three and four times harder than steel and are therefore scratch resistant, and transparent to visible light. Boron and silicon doping of the DLC coatings have produced coatings having improved optical properties and lower coating stress levels, but with slightly lower hardness.

  6. Moisture-resistant coatings for optical components

    NASA Technical Reports Server (NTRS)

    Hollahan, J. R.; Wydeven, T.; Johnson, C. C.

    1973-01-01

    Plasma polymerization technique is used to apply thin, adherent, hydrophobic coatings from chlorotrifluoroethylene monomer. Apparently much of the chlorine contained in original monomer is lost during polymerization, and characteristic C-Cl absorption in infrared region is essentially absent.

  7. Oxidation resistant nanocrystalline MCrAl(Y) coatings and methods of forming such coatings

    DOEpatents

    Cheruvu, Narayana S.; Wei, Ronghua

    2014-07-29

    The present disclosure relates to an oxidation resistant nanocrystalline coating and a method of forming an oxidation resistant nanocrystalline coating. An oxidation resistant coating comprising an MCrAl(Y) alloy may be deposited on a substrate, wherein M, includes iron, nickel, cobalt, or combinations thereof present greater than 50 wt % of the MCrAl(Y) alloy, chromium is present in the range of 15 wt % to 30 wt % of the MCrAl(Y) alloy, aluminum is present in the range of 6 wt % to 12 wt % of the MCrAl(Y) alloy and yttrium, is optionally present in the range of 0.1 wt % to 0.5 wt % of the MCrAl(Y) alloy. In addition, the coating may exhibit a grain size of 200 nm or less as deposited.

  8. Frost resistance of concrete surfaces coated with waterproofing materials

    NASA Astrophysics Data System (ADS)

    Klovas, A.; Dauksys, M.; Ciuprovaite, G.

    2015-03-01

    Present research lays emphasis on the problem of concrete surface exposed to aggressive surrounding quality. The test was conducted with concrete surfaces coated with different waterproofing materials exposed in solution of 3 % of sodium sulphate. Research was performed according to LST EN 1338:2003 standard requirements. Technological properties of concrete mixture as well as physical-mechanical properties of formed concrete specimens were established. The resistance of concrete to freezing - thawing cycles was prognosticated according to the porosity parameters established by the kinetic of water absorption. Five different waterproofing materials (coatings) such as liquid bitumen-rubber based, elastic fiber-strengthened, silane-siloxane based emulsion, mineral binder based and liquid rubber (caoutchouc) based coatings were used. Losses by mass of coating materials and specimens surface fractures were calculated based on the results of frost resistance test. Open code program "ImageJ" was used for visual analysis of concrete specimens. Based on the results, aggressive surrounding did not influence specimens coated with elastic, fibre-strengthened, mineral materials. On the other hand, specimens coated with liquid rubber (caoutchouc) based material were greatly influenced by aggressive surrounding. The biggest losses of specimen surface concrete (fractures) were obtained with silane-siloxane based emulsion coating. Generally, specimens coated with waterproofing materials were less influenced by aggressive surrounding compared with those without.

  9. Electrically resistive coating for remediation (regeneration) of a diesel particulate filter and method

    DOEpatents

    Phelps, Amanda C [Malibu, CA; Kirby, Kevin K [Calabasas Hills, CA; Gregoire, Daniel J [Thousand Oaks, CA

    2012-02-14

    A resistively heated diesel particulate filter (DPF). The resistively heated DPF includes a DPF having an inlet surface and at least one resistive coating on the inlet surface. The at least one resistive coating is configured to substantially maintain its resistance in an operating range of the DPF. The at least one resistive coating has a first terminal and a second terminal for applying electrical power to resistively heat up the at least one resistive coating in order to increase the temperature of the DPF to a regeneration temperature. The at least one resistive coating includes metal and semiconductor constituents.

  10. Enhancement of Corrosion Resistance of Zinc Coatings Using Green Additives

    NASA Astrophysics Data System (ADS)

    Punith Kumar, M. K.; Srivastava, Chandan

    2014-10-01

    In the present work, morphology, microstructure, and electrochemical behavior of Zn coatings containing non-toxic additives have been investigated. Zn coatings were electrodeposited over mild steel substrates using Zn sulphate baths containing four different organic additives: sodium gluconate, dextrose, dextrin, and saccharin. All these additives are "green" and can be derived from food contents. Morphological and structural characterization using electron microscopy, x-ray diffraction, and texture co-efficient analysis revealed an appreciable alteration in the morphology and texture of the deposit depending on the type of additive used in the Zn plating bath. All the Zn coatings, however, were nano-crystalline irrespective of the type of additive used. Polarization and electrochemical impedance spectroscopic analysis, used to investigate the effect of the change in microstructure and morphology on corrosion resistance behavior, illustrated an improved corrosion resistance for Zn deposits obtained from plating bath containing additives as compared to the pure Zn coatings.

  11. Oxidation resistant slurry coating for carbon-based materials

    NASA Technical Reports Server (NTRS)

    Smialek, J. L.; Rybicki, G. C. (Inventor)

    1985-01-01

    An oxidation resistant coating is produced on carbon-base materials, and the same processing step effects an infiltration of the substrate with silicon containing material. The process comprises making a slurry of nickel and silicon powders in a nitrocellulose lacquer, spraying onto the graphite or carbon-carbon substrate, and sintering in vacuum to form a fused coating that wets and covers the surface as well as penetrates into the pores of the substrate. Optimum wetting and infiltration occurs in the range of Ni-60 w/o Si to Ni-90 w/o Si with deposited thicknesses of 25-100 mg/sq. cm. Sintering temperatures of about 1200 C to about 1400 C are used, depending on the melting point of the specific coating composition. The sintered coating results in Ni-Si intermetallic phases and SiC, both of which are highly oxidation resistant.

  12. Wear Resistant Coating on Tungsten Carbide Hard Alloy

    NASA Astrophysics Data System (ADS)

    Oskolkova, T. N.

    2015-09-01

    The article reveals new knowledge about the role of zirconium in the composition of (Ti, Zr)N ion-plasma coating applied on WC10KS alloy. It is determined that when zirconium is introduced into ion-plasma coating TiN (50%) wear resistance and adhesion strength grow, nanohardness increases by 23% (up to 38500MPa), Yung's modulus rises by 67%, friction coefficient reduces to p = 0.07 and performance characteristics of a carbide alloy improve.

  13. RF surface resistance study of non-evaporable getter coatings

    NASA Astrophysics Data System (ADS)

    Malyshev, Oleg B.; Gurran, Lewis; Goudket, Philippe; Marinov, Kiril; Wilde, Stuart; Valizadeh, Reza; Burt, Graeme

    2017-02-01

    In many particle accelerators the beam parameters could be affected by the beam pipe wakefield impedance. It is vital to understand how the wakefield impedance might vary due to various coatings on the surface of the vacuum chamber, and this can be derived from surface resistance measurements. The bulk conductivity of two types of NEG films (dense and columnar) is determined. This is achieved by measuring the surface resistance of NEG-coated samples using an RF test cavity and fitting the experimental data to a standard theoretical model. The conductivity values obtained are then used to compare resistive wall wakefield effects in beam pipes coated with either of the two types of film.

  14. Cavitation erosion resistance of microarc oxidation coating on aluminium alloy

    NASA Astrophysics Data System (ADS)

    Cheng, Feng; Jiang, Shuyun; Liang, Jun

    2013-09-01

    Two ceramic coatings are prepared on 2124 aluminum alloy by microarc oxidation (MAO) technology. To explore the cavitation erosion resistance of the MAO coating, cavitation tests were performed by using a rotating-disk test rig. The mass losses, surface morphologies, chemical compositions and the phase constituents of the samples after cavitation tests were examined by using digital balance, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The results indicate that the MAO coatings can extend the incubation period of aluminum alloy, and thus enhance the cavitation erosion resistance as compared to the untreated aluminum alloy samples. After duration of 63 h cavitation test, a lot of erosion pits and the particles in various shapes can be observed on the surfaces of the aluminum alloy samples, while only a few erosion pits are observed on the MAO coatings. Moreover, the mean depths of erosion on the MAO coatings are lower in the first 30 h and are independent on erosion time. The results show that the cavitation erosion of MAO coating is governed by water mechanical impaction, resulting from the effects of brittle fracture of the MAO coating.

  15. Long Term Aging of Elastomers: Chemorheology of Viton B Fluorocarbon Elastomer

    NASA Technical Reports Server (NTRS)

    Kalfayan, S. H.; Silver, R. H.; Mazzeo, A. A.; Lui, S. T.

    1972-01-01

    The continuation of a study to ascertain the nature, extent, and the rate of chemical changes that take place in certain selected elastomers is reported. Under discussion is Viton B, regarded as a temperature and fuel resistant fluorocarbon rubber. The kinetic analysis of the chemical stress relaxation, and infrared and gel permeation chromatography analysis results are discussed.

  16. Pretreatment of Kapton-coated cable for epoxy adhesion

    NASA Astrophysics Data System (ADS)

    Carley, J. F.

    1984-01-01

    A new system to protect bonded strain gages that will be attached to the MFTF magnets was tested and indicated falling electrical resistance to ground, which is attributed to the infiltration of moisture. The most likely infiltration route seemed to be along the Kapton lead cable, which has an outer space of FEP fluorocarbon resin. The treated ends are embedded in the epoxy sealant, Hysol EA 934, a compound containing 70 wt % of asbestos. The tensile shear stresses required to pull the wires out of these embedments were measured. It is shown that the three levels of treatment are equally effective in raising the bond strength from 377 psi for the untreated cable to about twice that, 763 psi. It appears that the 40-s exposure to Tetra-Etch has penetrated the 0.5 mil fluorocarbon coating and attacks the Kapton film and the conductor coatings inside it.

  17. Atomic Oxygen-Resistant, Static-Dissipative, Pinhole-Free Coatings for Spacecraft

    DTIC Science & Technology

    2010-06-29

    CoatingsResistant to atomic oxygen  Static dissipative Sheet resistance < 105 Ω/square  UV-resistant  Pinhole-free  Thin To reduce weight...10 coatings had sheet resistance < 105 Ω/square both before and after exposure to atomic oxygen.  Optical Properties: 8 of 9 transparent coatings...bending, and thermal cycling had no effect on the coatings – No change in sheet resistance – No cracks or delaminations detected by SEM – No erosion

  18. Cavitation-Resistant Coatings for Hydropower Turbines

    DTIC Science & Technology

    2011-06-01

    and collapse of va- por pockets in a flowing liquid in regions of very low pressure ) in the tur- bine area. The level of cavitation typically destroys...power output. Unfortunately, this frequently results in cavitation (the rapid formation and collapse of vapor pockets in a flowing liquid in regions...of very low pressure ) in the turbine area. The level of ca- vitation typically destroys organic coatings in a relatively short time. Tra- ditional

  19. Fluorocarbon Adsorption in Hierarchical Porous Frameworks

    SciTech Connect

    Motkuri, Radha K.; Annapureddy, Harsha V.; Vijayakumar, M.; Schaef, Herbert T.; Martin, P F.; McGrail, B. Peter; Dang, Liem X.; Krishna, Rajamani; Thallapally, Praveen K.

    2014-07-09

    The adsorption behavior of a series of fluorocarbon derivatives was examined on a set of microporous metal organic framework (MOF) sorbents and another set of hierarchical mesoporous MOFs. The microporous M-DOBDC (M = Ni, Co) showed a saturation uptake capacity for R12 of over 4 mmol/g at a very low relative saturation pressure (P/Po) of 0.02. In contrast, the mesoporous MOF MIL-101 showed an exceptionally high uptake capacity reaching over 14 mmol/g at P/Po of 0.4. Adsorption affinity in terms of mass loading and isosteric heats of adsorption were found to generally correlate with the polarizability of the refrigerant with R12 > R22 > R13 > R14 > methane. These results suggest the possibility of exploiting MOFs for separation of azeotropic mixtures of fluorocarbons and use in eco-friendly fluorocarbon-based adsorption cooling and refrigeration applications.

  20. Contamination-resistant silica antireflective coating with closed ordered mesopores.

    PubMed

    Sun, Jinghua; Zhang, Qinghua; Ding, Ruimin; Lv, Haibing; Yan, Hongwei; Yuan, Xiaodong; Xu, Yao

    2014-08-21

    Porous silica optical antireflective (AR) coatings prepared by traditional sol-gel method have been extensively used for high power laser systems, but a serious drawback is that contamination existing in the high vacuum is easily absorbed by the disordered open pore structure, resulting in a fast decrease in transmittance. To improve the stability of transmittance in vacuum, a contamination-resistant silica AR coating with ordered mesopores completely closed by hydrophobic-oleophobic groups was successfully developed on a fused quartz substrate. The ordered mesopores in the coating were controlled under the direction of surfactant F127 via an evaporation-induced-self-assembling process and then were closed by post-grafting long chain fluoroalkylsilane. The grazing incidence small angle X-ray scattering (GISAXS) and the X-ray reflectivity (XRR) results indicated that the mesopores in the coating constructed a Fmmm orthorhombic symmetry structure with a (010) plane parallel to the substrate. Cage-like mesopores were confirmed by nitrogen adsorption-desorption analysis. The obtained coatings showed low surface roughness, excellent abrase-resistance and high transmittance of 100% on quartz substrate. Especially, the decrease of transmittance tested with polydimethylsiloxane pollution in vacuum within one-month was as small as 0.02%. The laser induced damage threshold was up to 59.8 J cm(-2) at a 12 ns laser pulse of 1053 nm wavelength. This work provides an alternative way to fabricate AR coatings with high stability.

  1. On the Resistance of Nanofibrous Superhydrophobic Coatings to Hydrostatic Pressures

    NASA Astrophysics Data System (ADS)

    Bucher, T. M.; Emami, B.; Vahedi Tafreshi, H.; Gad-El-Hak, M.; Tepper, G. C.

    2011-11-01

    We present a numerical study aimed at investigating the influence of microstructural parameters on the resistance of submerged fibrous superhydrophobic coatings to elevated hydrostatic pressures. In particular, we generate 3-D virtual geometries comprised of randomly or orthogonally oriented horizontal fibers with bimodal diameter distributions resembling the microstructure of coatings produced via DC and AC electrospinning, respectively. These virtual geometries are then used as the computational domain for performing Full Morphology (FM) simulations to establish a relationship between the coatings' critical pressure--pressure beyond which the surface departs from the Cassie state--and their microstructures. Our numerical simulations are aimed at providing guidelines for the design and optimization of the coatings' microstructures. Financial support from DARPA, contract number W91CRB-10-1-0003, is acknowledged.

  2. Coatings for directional eutectics. [for corrosion and oxidation resistance

    NASA Technical Reports Server (NTRS)

    Felten, E. J.; Strangman, T. E.; Ulion, N. E.

    1974-01-01

    Eleven coating systems based on MCrAlY overlay and diffusion aluminide prototypes were evaluated to determine their capability for protecting the gamma/gamma prime-delta directionally solidified eutectic alloy (Ni-20Cb-6Cr-2.5Al) in gas turbine engine applications. Furnace oxidation and hot corrosion, Mach 0.37 burner-rig, tensile ductility, stress-rupture and thermomechanical fatigue tests were used to evaluate the coated gamma/gamma prime-delta alloy. The diffusion aluminide coatings provided adequate oxidation resistance at 1144 K (1600 F) but offered very limited protection in 114 K (1600 F) hot corrosion and 1366 K (2000 F) oxidation tests. A platinum modified NiCrAlY overlay coating exhibited excellent performance in oxidation testing and had no adverse effects upon the eutectic alloy.

  3. Chromate-free corrosion resistant conversion coatings for aluminum alloys

    SciTech Connect

    Buchheit, R.G.; Drewien, C.A.; Martinez, M.A.; Stoner, G.E.

    1995-03-01

    Inorganic polycrystalline hydrotalcite, Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}3H{sub 2}O, coatings can be formed on aluminum and aluminum alloys by exposure to alkaline lithium carbonate solutions. This process is conducted using methods similar to traditional chromate conversion coating procedures, but does not use or produce toxic chemicals. The coating provides anodic protection and delays the onset of pitting during anodic polarization. Cathodic reactions are also inhibited which may also contribute to corrosion protection. Recent studies have shown that corrosion resistance can be increased by sealing hydrotalcite coated surfaces to transition metal salt solutions including Ce(NO{sub 3}){sub 3}, KMnO{sub 4} and Na{sub 2}MoO{sub 4}. Results from these studies are also reported.

  4. DIFFUSION COATINGS FOR CORROSION RESISTANT COMPONENTS IN COAL GASIFICATION SYSTEMS

    SciTech Connect

    Gopala N. Krishnan; Ripudaman Malhotra; Esperanza Alvarez; Kai-Hung Lau; Angel Sanjurjo

    2005-01-01

    Heat-exchangers, particle filters, turbines, and other components in integrated coal gasification combined cycle system must withstand the highly sulfiding conditions of the high temperature coal gas over an extended period of time. The performance of components degrades significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low cost alloy may improve is resistance to such sulfidation attack and decrease capital and operating costs. The alloys used in the gasifier service include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive nickel-cobalt alloys. During this reporting period we coated coupons of selected alloy steels with diffusion coatings of Cr and Al, as well as with titanium and tantalum nitrides. The coated samples were analyzed for their surface composition. In several instances, the samples were also cut to determine the depth profile of the coating. Several of the early runs did not yield uniform or deep enough coatings and hence a significant portion of the effort in this period was devoted fixing the problems with our fluidized bed reactor. Before the end of the quarter we had prepared a number of samples, many of them in duplicates, and sent one set to Wabash River Energy Laboratory for them to install in their gasifier. The gasifier was undergoing a scheduled maintenance and thus presented an opportunity to place some of our coupons in the stream of an operating gasifier. The samples submitted included coated and uncoated pairs of different alloys.

  5. Performances of silicone coated high resistive bakeliteRPC

    NASA Astrophysics Data System (ADS)

    Biswas, S.; Bhattacharya, Purba; Bhattacharya, S.; Bose, S.; Chattopadhyay, S.; Majumdar, N.; Mukhopadhyay, S.; Saha, S.; Viyogi, Y. P.

    2012-01-01

    Performances of several single gap (gas gap 2 mm) prototype Resistive Plate Chambers (RPC) made of high resistive (ρ˜1010-1012Ωcm) bakelite, commercially available in India have been studied in recent times. To make the inner electrode surfaces smooth, a thin coating of silicone has been applied. An efficiency >90% and time resolution ˜2ns (FWHM) have been obtained for both the streamer and the avalanche mode. The induced charge distributions of those silicone coated RPC are studied and the results are presented. A numerical study on the effect of surface roughness of the resistive electrodes on the electric field of the device has been carried out using Garfield-neBEM code. A few results for a simplified model representing surface roughness, measured using a surface profilometer for the bakelite surfaces, have also been presented.

  6. Erosion Resistant Coatings for Polymer Matrix Composites in Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Sutter, James K.; Naik, Subhash K.; Horan, Richard; Miyoshi, Kazuhisa; Bowman, Cheryl; Ma, Kong; Leissler, George; Sinatra, Raymond; Cupp, Randall

    2003-01-01

    Polymer Matrix Composites (PMCs) offer lightweight and frequently low cost alternatives to other materials in many applications. High temperature PMCs are currently used in limited propulsion applications replacing metals. Yet in most cases, PMC propulsion applications are not in the direct engine flow path since particulate erosion degrades PMC component performance and therefore restricts their use in gas turbine engines. This paper compares two erosion resistant coatings (SANRES and SANPRES) on PMCs that are useful for both low and high temperature propulsion applications. Collaborating over a multi-year period, researchers at NASA Glenn Research Center, Allison Advanced Developed Company, and Rolls-Royce Corporation have optimized these coatings in terms of adhesion, surface roughness, and erosion resistance. Results are described for vigorous hot gas/particulate erosion rig and engine testing of uncoated and coated PMC fan bypass vanes from the AE 3007 regional jet gas turbine engine. Moreover, the structural durability of these coatings is described in long-term high cycle fatigue tests. Overall, both coatings performed well in all tests and will be considered for applications in both commercial and defense propulsion applications.

  7. High Gloss Corrosion-Resistant Coatings

    DTIC Science & Technology

    1991-08-27

    34) 5,043,373 1 2 binder derived from the reaction of at least one polyes- HIGH GLOSS CORROSION-RESISTANT ter polyol and a diisocyanate in combination with a...comprises a polyurethane, and more particulary an aliphatic polyurethane derived from the reaction of a saturated polyester polyol and a multi...a molar ratio of acid to pentaerythritol of cyanates include the biurets of the formula: about 1:1 to 2.5:1

  8. Wear resistance of TiAlSiN thin coatings.

    PubMed

    Silva, F J G; Martinho, R P; Alexandre, R J D; Baptista, A P M

    2012-12-01

    In the last decades TiAIN coatings deposited by PVD techniques have been extensively investigated but, nowadays, their potential development for tribological applications is relatively low. However, new coatings are emerging based on them, trying to improve wear behavior. TiAlSiN thin coatings are now investigated, analyzing if Si introduction increases the wear resistance of PVD films. Attending to the application, several wear test configurations has been recently used by some researchers. In this work, TiAISiN thin coatings were produced by PVD Unbalanced Magnetron Sputtering technique and they were conveniently characterized using Scanning Electron Microscopy (SEM) provided with Energy Dispersive Spectroscopy (EDS), Atomic Force Microscopy (AFM), Electron Probe Micro-Analyzer (EPMA), Micro Hardness (MH) and Scratch Test Analysis. Properties as morphology, thickness, roughness, chemical composition and structure, hardness and film adhesion to the substrate were investigated. Concerning to wear characterization, two very different ways were chosen: micro-abrasion with ball-on-flat configuration and industrial non-standardized tests based on samples inserted in a feed channel of a selected plastic injection mould working with 30% (wt.) glass fiber reinforced polypropylene. TiAISiN coatings with a small amount of about 5% (wt.) Si showed a similar wear behavior when compared with TiAIN reported performances, denoting that Si addition does not improve the wear performance of the TiAIN coatings in these wear test conditions.

  9. Abrasion resistant coating and method of making the same

    DOEpatents

    Sordelet, Daniel J.; Besser, Matthew F.

    2001-06-05

    An abrasion resistant coating is created by adding a ductile phase to a brittle matrix phase during spray coating where an Al--Cu--Fe quasicrystalline phase (brittle matrix) and an FeAl intermetallic (ductile phase) are combined. This composite coating produces a coating mostly of quasicrystal phase and an inter-splat layer of the FeAl phase to help reduce porosity and cracking within the coating. Coatings are prepared by plasma spraying unblended and blended quasicrystal and intermetallic powders. The blended powders contain 1, 5, 10 and 20 volume percent of the intermetallic powders. The unblended powders are either 100 volume percent quasicrystalline or 100 volume percent intermetallic; these unblended powders were studied for comparison to the others. Sufficient ductile phase should be added to the brittle matrix to transform abrasive wear mode from brittle fracture to plastic deformation, while at the same time the hardness of the composite should not be reduced below that of the original brittle phase material.

  10. Abrasion Resistant Coating and Method of making the same

    SciTech Connect

    Sordelet, Daniel J.; Besser, Matthew F.

    1999-06-25

    An abrasion resistant coating is created by adding a ductile phase to a brittle matrix phase during spray coating where an Al-Cu-Fe quasicrystalline phase (brittle matrix) and an FeAl intermetallic (ductile phase) are combined. This composite coating produces a coating mostly of quasicrystal phase and an inter-splat layer of the FeAl phase to help reduce porosity and cracking within the coating. Coatings are prepared by plasma spraying unblended and blended quasicrystal and intermetallic powders. The blended powders contain 1, 5, 10 and 20 volume percent of the intermetallic powders. The unblended powders are either 100 volume percent quasicrystalline or 100 volume percent intermetallic; these unblended powders were studied for comparison to the others. Sufficient ductile phase should be added to the brittle matrix to transform abrasive wear mode from brittle fracture to plastic deformation, while at the same time the hardness of the composite should not be reduced below that of the original brittle phase material.

  11. Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

    NASA Astrophysics Data System (ADS)

    Amir, N.; Othman, W. M. S. W.; Ahmad, F.

    2015-07-01

    This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

  12. Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

    SciTech Connect

    Amir, N. Othman, W. M. S. W. Ahmad, F.

    2015-07-22

    This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

  13. Heat sealable, flame and abrasion resistant coated fabric

    NASA Technical Reports Server (NTRS)

    Tschirch, R. P.; Sidman, K. R. (Inventor)

    1983-01-01

    Flame retardant, abrasion resistant elastomeric compositions are disclosed which are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Heat sealable coated fabrics employing such elastomeric compositions as coating film are produced by dissolving the elastomeric composition to form a solution, casting the solution onto a release paper and drying it to form an elastomeric film. The film is then bonded to a woven, knitted, or felted fabric.

  14. Enhanced removal of radioactive particles by fluorocarbon surfactant solutions

    SciTech Connect

    Kaiser, R.; Harling, O.K.

    1993-08-01

    The proposed research addressed the application of ESI`s particle removal process to the non-destructive decontamination of nuclear equipment. The cleaning medium used in this process is a solution of a high molecular weight fluorocarbon surfactant in an inert perfluorinated liquid which results in enhanced particle removal. The perfluorinated liquids of interest, which are recycled in the process, are nontoxic, nonflammable, and environmentally compatible, and do not present a hazard to the ozone layer. The information obtained in the Phase 1 program indicated that the proposed ESI process is technically effective and economically attractive. The fluorocarbon surfactant solutions used as working media in the ESI process survived exposure of up to 10 Mrad doses of gamma rays, and are considered sufficiently radiation resistant for the proposed process. Ultrasonic cleaning in perfluorinated surfactant solutions was found to be an effective method of removing radioactive iron (Fe 59) oxide particles from contaminated test pieces. Radioactive particles suspended in the process liquids could be quantitatively removed by filtration through a 0.1 um membrane filter. Projected economics indicate a pre-tax pay back time of 1 month for a commercial scale system.

  15. Wear resistance of WC/Co HVOF-coatings and galvanic Cr coatings modified by diamond nanoparticles

    NASA Astrophysics Data System (ADS)

    Kandeva, M.; Grozdanova, T.; Karastoyanov, D.; Assenova, E.

    2017-02-01

    The efforts in the recent 20 years are related to search of ecological solutions in the tribotechnologies for the replacement of galvanic Cr coatings in the contact systems operating under extreme conditions: abrasion, erosion, cavitation, corrosion, shock and vibration loads. One of the solutions is in the composite coatings deposited by high velocity gas-flame process (HVOF). The present paper presents comparative study results for mechanical and tribological characteristics of galvanic Cr coatings without nanoparticles, galvanic Cr coatings modified by diamond nanoparticles NDDS of various concentration 0.6; 10; 15 и 20% obtained under three technological regimes, and composite WC-12Co coating. Comparative results about hardness, wear, wear resistance and friction coefficient are obtained for galvanic Cr-NDDS and WC-12Co coatings operating at equal friction conditions of dry friction on abrasive surface. The WC-12Co coating shows 5.4 to 7 times higher wear resistance compared to the galvanic Cr-NDDS coatings.

  16. Corrosion resistance of biodegradable Mg with a composite polymer coating.

    PubMed

    Chen, Peng; Sun, Jiadi; Zhu, Ye; Yu, Xun; Meng, Long; Li, Yang; Liu, Xiaoya

    2016-12-01

    Degrading Mg and its alloys are a category of implant materials for bone surgery, but rapid corrosion in physiological environment limits their clinical applications. To improve the corrosion resistance of Mg-based implants, a biodegradable composite polymer coating is deposited on an Mg rod in this work. The strategy is to decorate Mg surfaces with poly(γ-glutamic acid)-g-7-amino-4-methylcoumarin/hydroxyapatite (γ-PGA-g-AMC/HAp) composite nanoparticles through electrophoretic deposition in ethanol. The morphology and chemical composition of the resulting coating material are determined by scanning electron microscopy and Fourier transform infrared spectroscopy. Sample rods of bare Mg and coated Mg are implanted intramedullary into the femora of New Zealand white rabbits, periodic radiography and post-autopsy histopathology of each sample are analyzed. The obtained in vivo results clearly confirm that the coating material decreases degradation rate of the underlying Mg sample and appears good histocompatibility and osteoinductivity. The main aim of this work is to investigate the degradation process of bare Mg and coated Mg samples in bone environment and their effect on the surrounding bone tissue.

  17. High temperature resistant cermet and ceramic compositions. [for thermal resistant insulators and refractory coatings

    NASA Technical Reports Server (NTRS)

    Phillips, W. M. (Inventor)

    1978-01-01

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

  18. Selective Plasma Deposition of Fluorocarbon Films on SAMs

    NASA Technical Reports Server (NTRS)

    Crain, Mark M., III; Walsh, Kevin M.; Cohn, Robert W.

    2006-01-01

    A dry plasma process has been demonstrated to be useful for the selective modification of self-assembled monolayers (SAMs) of alkanethiolates. These SAMs are used, during the fabrication of semiconductor electronic devices, as etch masks on gold layers that are destined to be patterned and incorporated into the devices. The selective modification involves the formation of fluorocarbon films that render the SAMs more effective in protecting the masked areas of the gold against etching by a potassium iodide (KI) solution. This modification can be utilized, not only in the fabrication of single electronic devices but also in the fabrication of integrated circuits, microelectromechanical systems, and circuit boards. In the steps that precede the dry plasma process, a silicon mold in the desired pattern is fabricated by standard photolithographic techniques. A stamp is then made by casting polydimethylsiloxane (commonly known as silicone rubber) in the mold. The stamp is coated with an alkanethiol solution, then the stamp is pressed on the gold layer of a device to be fabricated in order to deposit the alkanethiol to form an alkanethiolate SAM in the desired pattern (see figure). Next, the workpiece is exposed to a radio-frequency plasma generated from a mixture of CF4 and H2 gases. After this plasma treatment, the SAM is found to be modified, while the exposed areas of gold remain unchanged. This dry plasma process offers the potential for forming masks superior to those formed in a prior wet etching process. Among the advantages over the wet etching process are greater selectivity, fewer pin holes in the masks, and less nonuniformity of the masks. The fluorocarbon films formed in this way may also be useful as intermediate layers for subsequent fabrication steps and as dielectric layers to be incorporated into finished products.

  19. Fluorocarbon adsorption in hierarchical porous frameworks

    SciTech Connect

    Motkuri, RK; Annapureddy, HVR; Vijaykumar, M; Schaef, HT; Martin, PF; McGrail, BP; Dang, LX; Krishna, R; Thallapally, PK

    2014-07-09

    Metal-organic frameworks comprise an important class of solid-state materials and have potential for many emerging applications such as energy storage, separation, catalysis and bio-medical. Here we report the adsorption behaviour of a series of fluorocarbon derivatives on a set of microporous and hierarchical mesoporous frameworks. The microporous frameworks show a saturation uptake capacity for dichlorodifluoromethane of >4 mmol g(-1) at a very low relative saturation pressure (P/P-o) of 0.02. In contrast, the mesoporous framework shows an exceptionally high uptake capacity reaching >14 mmol g(-1) at P/P-o of 0.4. Adsorption affinity in terms of mass loading and isosteric heats of adsorption is found to generally correlate with the polarizability and boiling point of the refrigerant, with dichlorodifluoromethane >chlorodifluoromethane >chlorotrifluoromethane >tetrafluoromethane >methane. These results suggest the possibility of exploiting these sorbents for separation of azeotropic mixtures of fluorocarbons and use in eco-friendly fluorocarbon-based adsorption cooling.

  20. Fluorocarbon adsorption in hierarchical porous frameworks

    NASA Astrophysics Data System (ADS)

    Motkuri, Radha Kishan; Annapureddy, Harsha V. R.; Vijaykumar, M.; Schaef, H. Todd; Martin, Paul F.; McGrail, B. Peter; Dang, Liem X.; Krishna, Rajamani; Thallapally, Praveen K.

    2014-07-01

    Metal-organic frameworks comprise an important class of solid-state materials and have potential for many emerging applications such as energy storage, separation, catalysis and bio-medical. Here we report the adsorption behaviour of a series of fluorocarbon derivatives on a set of microporous and hierarchical mesoporous frameworks. The microporous frameworks show a saturation uptake capacity for dichlorodifluoromethane of >4 mmol g-1 at a very low relative saturation pressure (P/Po) of 0.02. In contrast, the mesoporous framework shows an exceptionally high uptake capacity reaching >14 mmol g-1 at P/Po of 0.4. Adsorption affinity in terms of mass loading and isosteric heats of adsorption is found to generally correlate with the polarizability and boiling point of the refrigerant, with dichlorodifluoromethane >chlorodifluoromethane >chlorotrifluoromethane >tetrafluoromethane >methane. These results suggest the possibility of exploiting these sorbents for separation of azeotropic mixtures of fluorocarbons and use in eco-friendly fluorocarbon-based adsorption cooling.

  1. Application of cyclic fluorocarbon/argon discharges to device patterning

    SciTech Connect

    Metzler, Dominik; Uppiredi, Kishore; Bruce, Robert L.; Miyazoe, Hiroyuki; Zhu, Yu; Price, William; Sikorski, Ed S.; Li, Chen; Engelmann, Sebastian U.; Joseph, Eric A.; Oehrlein, Gottlieb S.

    2015-11-13

    With increasing demands on device patterning to achieve smaller critical dimensions and pitches for the 5nm node and beyond, the need for atomic layer etching (ALE) is steadily increasing. In this study, a cyclic fluorocarbon/Ar plasma is successfully used for ALE patterning in a manufacturing scale reactor. Self-limited etching of silicon oxide is observed. The impact of various process parameters on the etch performance is established. The substrate temperature has been shown to play an especially significant role, with lower temperatures leading to higher selectivity and lower etch rates, but worse pattern fidelity. The cyclic ALE approach established with this work is shown to have great potential for small scale device patterning, showing self-limited etching, improved uniformity and resist mask performance.

  2. Application of cyclic fluorocarbon/argon discharges to device patterning

    SciTech Connect

    Metzler, Dominik; Uppireddi, Kishore; Bruce, Robert L.; Miyazoe, Hiroyuki; Zhu, Yu; Price, William; Sikorski, Ed S.; Engelmann, Sebastian U.; Joseph, Eric A.; Li, Chen; Oehrlein, Gottlieb S.

    2016-01-15

    With increasing demands on device patterning to achieve smaller critical dimensions and pitches for the 5 nm node and beyond, the need for atomic layer etching (ALE) is steadily increasing. In this work, a cyclic fluorocarbon/Ar plasma is successfully used for ALE patterning in a manufacturing scale reactor. Self-limited etching of silicon oxide is observed. The impact of various process parameters on the etch performance is established. The substrate temperature has been shown to play an especially significant role, with lower temperatures leading to higher selectivity and lower etch rates, but worse pattern fidelity. The cyclic ALE approach established with this work is shown to have great potential for small scale device patterning, showing self-limited etching, improved uniformity and resist mask performance.

  3. Application of cyclic fluorocarbon/argon discharges to device patterning

    DOE PAGES

    Metzler, Dominik; Uppiredi, Kishore; Bruce, Robert L.; ...

    2015-11-13

    With increasing demands on device patterning to achieve smaller critical dimensions and pitches for the 5nm node and beyond, the need for atomic layer etching (ALE) is steadily increasing. In this study, a cyclic fluorocarbon/Ar plasma is successfully used for ALE patterning in a manufacturing scale reactor. Self-limited etching of silicon oxide is observed. The impact of various process parameters on the etch performance is established. The substrate temperature has been shown to play an especially significant role, with lower temperatures leading to higher selectivity and lower etch rates, but worse pattern fidelity. The cyclic ALE approach established with thismore » work is shown to have great potential for small scale device patterning, showing self-limited etching, improved uniformity and resist mask performance.« less

  4. White primer permits a corrosion-resistant coating of minimum weight

    NASA Technical Reports Server (NTRS)

    Albrecht, R. H.; Jensen, D. P.; Schnake, P.

    1966-01-01

    White primer for coating 2219 aluminum alloy supplies a base for a top coating of enamel. A formulation of pigments and vehicle results in a primer with high corrosion resistance and minimum film thickness.

  5. Alkali corrosion resistant coatings and ceramic foams having superfine open cell structure and method of processing

    DOEpatents

    Brown, Jr., Jesse J.; Hirschfeld, Deidre A.; Li, Tingkai

    1993-12-07

    Alkali corrosion resistant coatings and ceramic foams having superfine open cell structure are created using sol-gel processes. The processes have particular application in creating calcium magnesium zirconium phosphate, CMZP, coatings and foams.

  6. Microstructure and corrosion resistance of phytic acid conversion coatings for magnesium alloy

    NASA Astrophysics Data System (ADS)

    Cui, Xiufang; Li, Qingfen; Li, Ying; Wang, Fuhui; Jin, Guo; Ding, Minghui

    2008-12-01

    In this paper, a new innoxious and pollution-free chemical protective coating for magnesium alloys, phytic acid conversion coating, was prepared. The conversion coatings are found to have high cover ratio and no cracks are found by atomic force microscopes (AFM) and scanning electron microscopy (SEM). The main elements of the conversion coatings are Mg, Al, O, P and C by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The chemical state of the elements in the coatings was also investigated by Fourier transform infrared spectroscopy (FTIR). AES depth profile analysis suggests that the thickness of the conversion coating is about 340 nm. The corrosion resistance of the coatings was evaluated by polarization curves. The results indicate that the corrosion resistance for the conversion coated AZ91D magnesium alloys in 3.5% NaCl solution increases markedly. The mechanisms of corrosion resistance and coatings formation are also discussed.

  7. Corrosion resistance of polyurethane-coated nitinol cardiovascular stents.

    PubMed

    Mazumder, M M; De, S; Trigwell, S; Ali, N; Mazumder, M K; Mehta, J L

    2003-01-01

    Corrosion of metal stents implanted inside an artery can have two adverse effects: (1) tissue reaction and possible toxic effects from the metal ions leaching out of the stent, and (2) loss of mechanical strength of the stent caused by corrosion. The corrosion resistance of Nitinol (Nickel-Titanium) stents and its modulation with different film thickness of polymer coating was studied against an artificial physiological solution using a Potentiostat/Galvanostat and an electrochemical corrosion cell. The corrosion rate decreased rapidly from 275 microm/year for an uncoated surface down to less than 13 microm/year for a 30 microm thick polyurethane coating. Stainless steel (316L) and Nitinol both contain potentially toxic elements, and both are subject to stress corrosion. Minimization of corrosion can significantly reduce both tissue reaction and structural degradation.

  8. Low conductivity and sintering-resistant thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming (Inventor); Miller, Robert A. (Inventor)

    2004-01-01

    A thermal barrier coating composition comprising a base oxide, a primary stabilizer oxide, and at least one dopant oxide is disclosed. Preferably, a pair of group A and group B defect cluster-promoting oxides is used in conjunction with the base and primary stabilizer oxides. The new thermal barrier coating is found to have significantly lower thermal conductivity and better sintering resistance. The base oxide is selected from the group consisting of zirconia and hafnia and combinations thereof. The primary stabilizing oxide is selected from the group consisting of yttria, dysprosia, erbia and combinations thereof. The dopant or group A and group B cluster-promoting oxide dopants are selected from the group consisting of rare earth metal oxides, transitional metal oxides, alkaline earth metal oxides and combinations thereof. The dopant or dopants preferably have ionic radii different from those of the primary stabilizer and/or the base oxides.

  9. Low conductivity and sintering-resistant thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming (Inventor); Miller, Robert A. (Inventor)

    2007-01-01

    A thermal barrier coating composition is provided. The composition has a base oxide, a primary stabilizer, and at least two additional cationic oxide dopants. Preferably, a pair of group A and group B defect cluster-promoting oxides is used in conjunction with the base and primary stabilizer oxides. The new thermal barrier coating is found to have significantly lower thermal conductivity and better sintering resistance. In preferred embodiments, the base oxide is selected from zirconia and hafnia. The group A and group B cluster-promoting oxide dopants preferably are selected such that the group A dopant has a smaller cationic radius than the primary stabilizer oxide, and so that the primary stabilizer oxide has a small cationic radius than that of the group B dopant.

  10. Low conductivity and sintering-resistant thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming (Inventor); Miller, Robert A. (Inventor)

    2006-01-01

    A thermal barrier coating composition is provided. The composition has a base oxide, a primary stabilizer, and at least two additional cationic oxide dopants. Preferably, a pair of group A and group B defect cluster-promoting oxides is used in conjunction with the base and primary stabilizer oxides. The new thermal barrier coating is found to have significantly lower thermal conductivity and better sintering resistance. In preferred embodiments, the base oxide is selected from zirconia and hafnia. The group A and group B cluster-promoting oxide dopants preferably are selected such that the group A dopant has a smaller cationic radius than the primary stabilizer oxide, and so that the primary stabilizer oxide has a small cationic radius than that of the group B dopant.

  11. Tantalum-based thin film coatings for wear resistant arthroprostheses.

    PubMed

    Balagna, C; Faga, M G; Spriano, S

    2011-10-01

    Cobalt-chromium-molybdenum alloys with high carbon content (HC-CoCrMo) are widely used as materials for arthroprosthesis, in particular in metal-on-metal (MoM) hip joints. In spite of their good wear and corrosion resistance, production of metallic wear particles and metal ion release will occur on a large time-scale. An enhancement of the metal ion level in the patient's blood and urine is often reported in clinical data. Hypersensitivity, inflammatory response and cell necrosis can occur as consequence. So implants on young patients and women on childbearing age are not so widespread. The aim of this research is the realization of a thin film coating in order to improve the biocompatibility of Co-based alloys and to reduce debris production, ion release and citotoxicity. The innovative process consists of a thermal treatment in molten salts, in order to obtain a tantalum enriched thin film coating. Tantalum is chosen because it is considered a biocompatible metal with high corrosion resistance and low ion release. Three HC-CoCrMo alloys, produced by different manufacturing processes, are tested as substrates. The coating is a thin film of TaC or it can be composed by a multilayer of two tantalum carbides and metallic tantalum, depending on the temperature of the treatment and on the carbon content of the substrate. The thin films as well the substrates are characterized from the structural, chemical and morphological point of view. Moreover mechanical behaviour of treated and untreated materials is analyzed by means of nanohardness, scratch and ball-on-disc wear tests. The coating increases the mechanical and tribological properties of HC-CoCrMo.

  12. Effect of Chromium Addition to the Low Temperature Hot Corrosion Resistance of Platinum Modified Aluminide Coatings.

    DTIC Science & Technology

    1985-12-01

    Diffusion aluminide coatings were the first coatings developed for hot corrosion resistance. Aluminum is applied to the surface of the superalloy by a...D.H., "Mechanisms of Formation of Diffusion Aluminide Coatings on Nickel-oase Superalloys , Oxidation of Metals, v. 3, pp. 475-477, 1971. 17. Lehnert...Classification) E.FFECT OF CHROMIUJM ADDITION TO THE LOW TEMPERATURE HOT CORROSION RESISTANCE OF PLATINUM MODIFIED ALUMINIDE COATINGS 2 PERSONAL AUTHOR(S) Dust

  13. Preparation and corrosion resistance of MAO/Ni-P composite coat on Mg alloy

    NASA Astrophysics Data System (ADS)

    Fan, Xizhi; Wang, Ying; Zou, Binglin; Gu, Lijian; Huang, Wenzhi; Cao, Xueqiang

    2013-07-01

    Microarc oxidation (MAO) coat was designed as an intermediate layer for the electroless plated Ni-P top coat, providing inert surface and necessary hardness for Mg alloy substrate. The composite coat was successfully prepared to improve the corrosion resistance of Mg alloy. The preparation and the characterization of the composite coat were investigated. The results show that the pre-treatment of MAO before electroless plating plays an important role in the deposition of compact composite coat. The activation (by HF solution) makes the MAO coat dense with uniform cracks which supply excellent bonding interface for Ni-P coat. Compared with monolithic MAO or Ni-P coat, the composite coat has excellent corrosion resistance and stable bonding interface. There is main pit corrosion at substrate after the corrosive medium penetrating through the whole coat. With the inert MAO interlayer, the electrochemical corrosion between the Ni-P and substrate is effectively inhibited.

  14. High-temperature corrosion resistance of ceramics and ceramic coatings

    SciTech Connect

    Tortorelli, P.F.

    1996-06-01

    Ceramics and ceramic composites offer the potential to operate fossil energy systems at the higher temperatures necessary for improved energy efficiency and better environmental control. However, because many fossil fuel-derived processes contain sulfur, chlorine, and carbon, as well as oxygen, degradation from high-temperature corrosion and environmental effects arising from reactions of solids with gases and condensable products is a common life-determining factor in operating systems. Ceramic-based products are not immune to such degradation; adequate corrosion resistance must be assured to exploit the technical and economic potential of such materials. This is normally accomplished by using stable, sound oxides that exist in their bulk form, that naturally grow as surface layers upon exposure to an oxidizing environment, or that are deposited as a coating on a susceptible material. It is therefore important to examine the critical issues with respect to more environmental stability of ceramics that have the potential to be corrosion resistant in particular fossil environments. Key aspects include not only chemical compatibility, but the influence of the environment on the mechanical behavior of the ceramic materials. In addition, for coatings, the mechanical reliability of the ceramic is a key issue in that an otherwise corrosion-resistant surface layer must remain sound and adherent in order to provide protection to the underlying substrate. The purpose of this work is to support the development of advanced ceramics and ceramic composites for applications in fossil environments by examining critical issues related to high-temperature corrosion resistance. More specifically, the overall objective of this task is to examine the chemical compatibility and reliability of potentially corrosion-resistant ceramics being developed as protective overcoats and/or structural materials as parts of other work elements funded by the AR&TD Program.

  15. A new diffusion-inhibited oxidation-resistant coating for superalloys

    NASA Technical Reports Server (NTRS)

    Gedwill, M. A.; Glasgow, T. K.; Levine, S. R.

    1981-01-01

    A concept for enhanced protection of superalloys consists of adding an oxidation- and diffusion-resistant cermet layer between the superalloy and the outer oxidation-resistant metallic alloy coating. Such a duplex coating was compared with a physical-vapor-deposited (PVD) NiCrAlY coating in cyclic oxidation at 1150 C. The substrate alloy was MA 754 - an oxide-dispersion-strengthened superalloy that is difficult to coat. The duplex coating, applied by plasma spraying, outperformed the PVD coating on the basis of weight change and both macroscopic and metallographic observations.

  16. Highly defective oxides as sinter resistant thermal barrier coating

    DOEpatents

    Subramanian, Ramesh

    2005-08-16

    A thermal barrier coating material formed of a highly defective cubic matrix structure having a concentration of a stabilizer sufficiently high that the oxygen vacancies created by the stabilizer interact within the matrix to form multi-vacancies, thereby improving the sintering resistance of the material. The concentration of stabilizer within the cubic matrix structure is greater than that concentration of stabilizer necessary to give the matrix a peak ionic conductivity value. The concentration of stabilizer may be at least 30 wt. %. Embodiments include a cubic matrix of zirconia stabilized by at least 30-50 wt. % yttria, and a cubic matrix of hafnia stabilized by at least 30-50 wt. % gadolinia.

  17. Electrical properties and fatigue resistance of polyamide 6,6 fabrics with nanocrystal silver coating.

    PubMed

    Wang, R X; Tao, X M; Wang, Y; Wang, G F

    2009-05-01

    Nanocrystalline silver was coated on plain woven fabrics made from continuous polyamide multifilament yarns by sputtering technique. Electrical conductivity and abrasion resistances of the coating fabric were measured. There was a minimum value of resistance when the coating thickness varies. The critical coating thickness at the minimum resistance was found to be much greater than that necessary to form a continuous layer of coating on a single fabric. X-ray diffraction (XRD) and transmission electron microscope (TEM), and field emission scanning electronic microscopy (FESEM) were employed to identify the contributing factors of dips between two adjacent parallel fibres and cross-over junction of the warp and weft yarns.

  18. Study and Applications of Dynamic Resistance Profiles During Resistance Spot Welding of Coated Hot-Stamping Steels

    NASA Astrophysics Data System (ADS)

    Ighodaro, Osayande Lord-Rufus; Biro, Elliot; Zhou, Y. Norman

    2017-02-01

    This work compares the role of press hardened steel coating type (Al-Si and GA) on resistance spot welding by analyzing the dynamic resistance curves measured during the weld cycles of the respective materials. It was seen that the dynamic resistance profiles for GA- and Al-Si-coated steels are similar. But the GA specimens exhibited higher resistance than Al-Si-coated specimens in the as-received condition, while the Al-Si-coated specimens exhibited higher resistance after hot stamping. From the early stages of the dynamic resistance profiles, data were obtained and applied for computing the values of components of resistances associated with the different coatings since each coating exhibits characteristic value at the early stages. The results revealed that at the start of the welding cycle, the resistance of the electrode/sheet interface was significantly higher than that of the faying surface or the bulk resistance regardless of whether the steel was Al-Si- or GA-coated. The possible uses of these resistance values in studying welding current requirement and electrode tip life were discussed.

  19. An Oxidation-Resistant Coating Alloy for Gamma Titanium Aluminides

    NASA Technical Reports Server (NTRS)

    Brady, Michael P.; Smialek, James L.; Brindley, William J.

    1997-01-01

    Titanium aluminides based on the g-phase (TiAl) offer the potential for component weight savings of up to 50 percent over conventional superalloys in 600 to 850 C aerospace applications. Extensive development efforts over the past 10 years have led to the identification of "engineering" gamma-alloys, which offer a balance of room-temperature mechanical properties and high-temperature strength retention. The gamma class of titanium aluminides also offers oxidation and interstitial (oxygen and nitrogen) embrittlement resistance superior to that of the alpha(sub 2) (Ti3Al) and orthorhombic (Ti2AlNb) classes of titanium aluminides. However, environmental durability is still a concern, especially at temperatures above 750 to 800 C. Recent work at the NASA Lewis Research Center led to the development of an oxidation-resistant coating alloy that shows great promise for the protection of gamma titanium aluminides.

  20. DIFFUSION COATINGS FOR CORROSION RESISTANT COMPONENTS IN COAL GASIFICATION SYSTEMS

    SciTech Connect

    Gopala N. Krishnan; Ripudaman Malhotra; Angel Sanjurjo

    2004-05-01

    Heat-exchangers, filters, turbines, and other components in integrated coal gasification combined cycle system must withstand demanding conditions of high temperatures and pressure differentials. Under the highly sulfiding conditions of the high temperature coal gas, the performance of components degrade significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low cost alloy may improve is resistance to such sulfidation attack and decrease capital and operating costs. A review of the literature indicates that the corrosion reaction is the competition between oxidation and sulfidation reactions. The Fe- and Ni-based high-temperature alloys are susceptible to sulfidation attack unless they are fortified with high levels of Cr, Al, and Si. To impart corrosion resistance, these elements need not be in the bulk of the alloy and need only be present at the surface layers.

  1. Heat-resistant coatings for the high-pressure turbine blades of promising GTEs

    NASA Astrophysics Data System (ADS)

    Kablov, E. N.; Muboyadzhyan, S. A.

    2012-01-01

    Heat-resistant coatings are considered for the external surface of high-pressure turbine (HPT) single-crystal blades for promising gas turbine engines (GTEs) made from carbon-free nickel superalloys with rhenium or rhenium plus ruthenium. Nickel superalloys covered with heat-resistant coatings consisting of heat-resistant connecting layers and an external ZrO2-(7-8 wt %)Y2O3 ceramic layer are subjected to heat resistance and high-temperature tests. The test results are used to choose the heat-resistant layer that ensures the highest properties of a composition heat-resistant coating. The use of sequential chemical and physical deposition methods for coating layers is shown to be required to protect HPT blades in promising GTEs. Medium-frequency magnetron plasmachemical deposition of ceramic layers in heat-resistant coatings with a low thermal conductivity is found to be promising.

  2. Development of wear resistant ceramic coatings for diesel engine components

    SciTech Connect

    Haselkorn, M.H. )

    1992-04-01

    Improved fuel economy and a reduction of emissions can be achieved by insulation of the combustion chamber components to reduce heat rejection. However, insulating the combustion chamber components will also increase the operating temperature of the piston ring/cylinder liner interface from approximately 150{degree}C to over 300{degree}C. Existing ring/liner materials can not withstand these higher operating temperatures and for this reason, new materials need to be developed for this critical tribological interface. The overall goal of this program is the development of piston ring/cylinder liner material pairs which would be able to provide the required friction and wear properties at these more severe operating conditions. More specifically, this program first selected, and then evaluated, potential d/wear resistant coatings which could be applied to either piston rings an or cylinder liners and provide, at 350{degree}C under lubricated conditions, coefficients of friction below 0.1 and wear rates of less than 25 {times} lO{sup {minus}6} mm/hour. The processes selected for applying the candidate wear resistant coatings to piston rings and/or cylinder liners were plasma spraying, chemical vapor, physical vapor and low temperature arc vapor deposition techniques as well as enameling techniques.

  3. Oxidation resistance and mechanical properties of HfC nanowire-toughened ultra-high temperature ceramic coating for SiC-coated C/C composites

    NASA Astrophysics Data System (ADS)

    Ren, Jincui; Zhang, Yulei; Hu, Heng; Fei, Tian; Li, Hejun

    2016-01-01

    To improve the oxidation resistance of carbon/carbon (C/C) composites, a dense HfC nanowire-toughened ultra-high temperature ceramic multiphase coating was prepared on SiC-coated C/C composites by chemical vapor deposition (CVD) and pack cementation. The microstructure, mechanical and oxidation resistance properties of the coating were investigated. The results show that the HfC nanowires in the coating could suppress the cracking of the coating and then improve the toughness of the coating. The flexural property, thermal shock and isothermal oxidation resistance of the coating were all improved due to the incorporation of HfC nanowires.

  4. Flame-resistant textiles

    NASA Technical Reports Server (NTRS)

    Fogg, L. C.; Stringham, R. S.; Toy, M. S.

    1980-01-01

    Flame resistance treatment for acid resistant polyamide fibers involving photoaddition of fluorocarbons to surface has been scaled up to treat 10 yards of commercial width (41 in.) fabric. Process may be applicable to other low cost polyamides, polyesters, and textiles.

  5. Development of a special purpose spacecraft coating, phase 4

    NASA Technical Reports Server (NTRS)

    Gillman, H. D.

    1980-01-01

    Coating formulations based on a fluorocarbon resin were evaluated for use on spacecraft exteriors. Formulations modified with an acrylic resin were found to have excellent offgassing properties. A much less expensive process for increasing to solid content of the fluorocarbon latex was developed.

  6. Blanch Resistant and Thermal Barrier NiAl Coating Systems for Advanced Copper Alloys

    NASA Technical Reports Server (NTRS)

    Raj, Sai V. (Inventor)

    2005-01-01

    A method of forming an environmental resistant thermal barrier coating on a copper alloy is disclosed. The steps include cleansing a surface of a copper alloy, depositing a bond coat on the cleansed surface of the copper alloy, depositing a NiAl top coat on the bond coat and consolidating the bond coat and the NiAl top coat to form the thermal barrier coating. The bond coat may be a nickel layer or a layer composed of at least one of copper and chromium-copper alloy and either the bond coat or the NiAl top coat or both may be deposited using a low pressure or vacuum plasma spray.

  7. Structure Analysis Of Corrosion Resistant Thermal Sprayed Coatings On Low Alloy Steels

    SciTech Connect

    Chaliampalias, D.; Vourlias, G.; Pistofidis, N.; Pavlidou, E.; Stergiou, A.; Stergioudis, G.; Polychroniadis, E. K.

    2007-04-23

    Metallic coatings have been proved to reduce the rate of corrosion of steel in various atmospheres. In this work the structure of Al, Cu-Al and Zn thermal sprayed coatings is examined. The as formed coatings are extremely rough, and they are composed of several phases which increase corrosion resistance as it was determined Salt Spray Chamber tests.

  8. Investigation to identify paint coatings resistive to microorganism growth

    NASA Technical Reports Server (NTRS)

    Cooper, C. W.; Kemp, H. T.

    1971-01-01

    All selected coatings contain nutrients that support microbial growth and survival. Incorporation of microbiocidal agents into coatings more susceptible to attack is recommended for improved inhibition of microorganism growth and for increased protection against deterioration of coatings by microorganisms.

  9. 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.

  10. On the Problem of Wear Resistant Coatings Separation From Tools and Machine Elements

    NASA Astrophysics Data System (ADS)

    Petrushin, S. I.; Gubaidulina, R. H.; Gruby, S. V.; Likholat, A. V.

    2015-09-01

    The article considers separation of wear resistant coatings of tool and engineering materials which arises both during coating fabrication and use of the product. The cause of this phenomenon is assumed to be related to thermal residual stresses generating on the coating- substrate border. These stresses have been analyzed and methods are provided to calculate it after produced composite material is cooled down from the temperature of coating synthesis to the ambient temperature. A no-fracture condition has been stated in relation to coating- substrate thicknesses, temperature differences and physical and mechanical properties of combined materials. The issue of intermediate layer incorporation with pre-set parameters has been discussed. A co-effect of thermal residual and functional stresses on the strength of the boundary layer has been considered when heating, tension and compression of a product with wear resistant coating. Conclusions have been made, as well as recommendations to improve fracture strength of products with thin wear resistant coatings.

  11. The Development of Erosion and Impact Resistant Turbine Airfoil Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    2007-01-01

    Thermal barrier coatings are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments and extend component lifetimes. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Advanced 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 doped 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 and impact damage mechanisms of the thermal barrier coatings will also be discussed.

  12. The Application of Heat and Corrosion Resistant Phosphate Coatings Under Steam Pressure

    DTIC Science & Technology

    1974-03-01

    SUPPLEMENTARY NorEs 19. KEY ’WORDS (Continue on reverae aide if neceasary and Identify by block number) 1. Phosphate coatings 4 . Corrosion resistance 2...Manganese phosphate 5. Pressure Vessel 3 . Heat resistance 20. ABSTRACT (Continue on reveae aide it necesary and Identify by bloch number) Processing...2 Manganese Phosphate Coatings Applied in a 15 Conventional Bath with and without Mangan- ese Citrate 3 Me ganese Phosphate Coatings Applied in a 18

  13. Coupling Losses and Transverse Resistivity of Multifilament YBCO Coated Superconductors (Postprint)

    DTIC Science & Technology

    2012-02-01

    AFRL-RZ-WP-TP-2012-0125 COUPLING LOSSES AND TRANSVERSE RESISTIVITY OF MULTIFILAMENT YBCO COATED SUPERCONDUCTORS (POSTPRINT) M. Polak, E... YBCO COATED SUPERCONDUCTORS (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62203F 6. AUTHOR(S) M...filamentary YBCO coated conductors. A 10 mm wide YBCO coated conductor was subdivided into 20 filaments by laser ablation. We measured the frequency

  14. A review of the use of wear-resistant coatings in the cutting-tool industry

    NASA Technical Reports Server (NTRS)

    Salik, J.

    1983-01-01

    The main mechanisms involved in the wear of cutting tools are reviewed. Evaluation of the different coating properties required for the reduction of the different kinds of wear was also reviewed. The types of coatings and their ranges of applicability are presented and discussed in view of their properties. Various coating processes as well as their advantages and shortcomings are described. Potential future developments in the field of wear-resistant coatings are discussed.

  15. Corrosion resistant thermal barrier coating. [protecting gas turbines and other engine parts

    NASA Technical Reports Server (NTRS)

    Levine, S. R.; Miller, R. A.; Hodge, P. E. (Inventor)

    1981-01-01

    A thermal barrier coating system for protecting metal surfaces at high temperature in normally corrosive environments is described. The thermal barrier coating system includes a metal alloy bond coating, the alloy containing nickel, cobalt, iron, or a combination of these metals. The system further includes a corrosion resistant thermal barrier oxide coating containing at least one alkaline earth silicate. The preferred oxides are calcium silicate, barium silicate, magnesium silicate, or combinations of these silicates.

  16. A study of the deposition of carbide coatings on graphite fibers. [to increase electrical resistance

    NASA Technical Reports Server (NTRS)

    Suplinskas, R. J.; Henze, T. W.

    1979-01-01

    The chemical vapor deposition of boron carbide and silicon carbide on graphite fibers to increase their electrical resistance was studied. Silicon carbide coatings were applied without degradation of the mechanical properties of the filaments. These coatings typically added 1000 ohms to the resistance of a filament as measured between two mercury pools. When SiC-coated filaments were oxidized by refluxing in boiling phosphoric acid, average resistance increased by an additional 1000 ohms; in addition resistance increases as high as 150 K ohms and breakdown voltages as high as 17 volts were noted. Data on boron carbide coatings indicated that such coatings would not be effective in increasing resistance, and would degrade the mechanical properties.

  17. The hardness, adhesion, and wear resistance of coatings developed for cobalt-base alloys

    SciTech Connect

    Cockeram, B.V.; Wilson, W.L.

    2000-05-01

    One potential approach for reducing the level of nuclear plant radiation exposure that results from activated cobalt wear debris is the use of a wear resistant coating. However, large differences in stiffness between a coating/substrate can result in high interfacial stresses that produce coating de-adhesion when a coated substrate is subjected to high stress wear contact. Scratch adhesion and indentation tests have been used to identify four promising coating processes [1,2]: (1) the use of a thin Cr-nitride coating with a hard and less-stiff interlayer, (2) the use of a thick, multilayered Cr-nitride coating with graded layers, (3) use of the duplex approach, or nitriding to harden the material subsurface followed by application of a multilayered Cr-nitride coating, and (4) application of nitriding alone. The processing, characterization, and adhesion of these coating systems are discussed. The wear resistance and performance has been evaluated using laboratory pin-on-disc, 4-ball, and high stress rolling contact tests. Based on the results of these tests, the best coating candidate from the high-stress rolling contact wear test was the thin duplex coating, which consists of ion nitriding followed deposition of a thin Cr-nitride coating, while the thin Cr-nitride coating exhibited the best results in the 4-ball wear test.

  18. Ceramic Coatings for Corrosion Resistant Nuclear Waste Container Evaluated in Simulated Ground Water at 90?C

    SciTech Connect

    Haslam, J J; Farmer, J C

    2004-03-31

    Ceramic materials have been considered as corrosion resistant coatings for nuclear waste containers. Their suitability can be derived from the fully oxidized state for selected metal oxides. Several types of ceramic coatings applied to plain carbon steel substrates by thermal spray techniques have been exposed to 90 C simulated ground water for nearly 6 years. In some cases no apparent macroscopic damage such as coating spallation was observed in coatings. Thermal spray processes examined in this work included plasma spray, High Velocity Oxy Fuel (HVOF), and Detonation Gun. Some thermal spray coatings have demonstrated superior corrosion protection for the plain carbon steel substrate. In particular the HVOF and Detonation Gun thermal spray processes produced coatings with low connected porosity, which limited the growth rate of corrosion products. It was also demonstrated that these coatings resisted spallation of the coating even when an intentional flaw (which allowed for corrosion of the carbon steel substrate underneath the ceramic coating) was placed in the coating. A model for prediction of the corrosion protection provided by ceramic coatings is presented. The model includes the effect of the morphology and amount of the porosity within the thermal spray coating and provides a prediction of the exposure time needed to produce a crack in the ceramic coating.

  19. Characterization of Tape Adhesion to Chemical Agent Resistant Coatings

    DTIC Science & Technology

    2015-01-01

    mitigating properties into CARC systems currently in use. The performance of these coatings is evaluated using MIL -DTL-530721. During the coating...application phase and in the field, a tape pull off test is required by MIL -DTL-53072 to gauge adhesive strength of a coating to a primer or substrate...properties into CARC systems currently in use. The performance of these coatings is evaluated using MIL -DTL-53072 1 . During the coating application phase

  20. Bioinspired Zwitterionic Surface Coatings with Robust Photostability and Fouling Resistance.

    PubMed

    Huang, Chun-Jen; Chu, Sz-Hau; Wang, Lin-Chuan; Li, Chien-Hung; Lee, T Randall

    2015-10-28

    Great care has been paid to the biointerface between a bulk material and the biological environment, which plays a key role in the optimized performance of medical devices. In this work, we report a new superhydrophilic adsorbate, called L-cysteine betaine (Cys-b), having branched zwitterionic groups that give rise to surfaces and nanoparticles with enhanced chemical stability, biofouling resistance, and inertness to environmental changes. Cys-b was synthesized from the amphoteric sulfur-containing amino acid, L-cysteine (Cys), by quaternization of its amino group. Gold surfaces modified with Cys-b exhibited prominent repellence against the nonspecific adsorption of proteins, bacteria, and fibroblast cells. In addition, Cys-b existed in zwitterionic form over a wide pH range (i.e., pH 3.4 to 10.8), and showed excellent suppression in photoinduced oxidation on gold substrates. Furthermore, the modification of hollow Ag@Au nanoshells with Cys-b gave rise to nanoparticles with excellent colloidal stability and resistance to coordinative interaction with Cu(2+). Taken together, the unique features of Cys-b offer a new nanoscale coating for use in a wide spectrum of applications.

  1. Materials for Advanced Turbine Engines (MATE). Project 4: Erosion resistant compressor airfoil coating

    NASA Technical Reports Server (NTRS)

    Rashid, J. M.; Freling, M.; Friedrich, L. A.

    1987-01-01

    The ability of coatings to provide at least a 2X improvement in particulate erosion resistance for steel, nickel and titanium compressor airfoils was identified and demonstrated. Coating materials evaluated included plasma sprayed cobalt tungsten carbide, nickel carbide and diffusion applied chromium plus boron. Several processing parameters for plasma spray processing and diffusion coating were evaluated to identify coating systems having the most potential for providing airfoil erosion resistance. Based on laboratory results and analytical evaluations, selected coating systems were applied to gas turbine blades and evaluated for surface finish, burner rig erosion resistance and effect on high cycle fatigue strength. Based on these tests, the following coatings were recommended for engine testing: Gator-Gard plasma spray 88WC-12Co on titanium alloy airfoils, plasma spray 83WC-17Co on steel and nickel alloy airfoils, and Cr+B on nickel alloy airfoils.

  2. Development and Life Prediction of Erosion Resistant Turbine Low Conductivity Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    Future rotorcraft propulsion systems are required to operate under highly-loaded conditions and in harsh sand erosion environments, thereby imposing significant material design and durability issues. The incorporation of advanced thermal barrier coatings (TBC) in high pressure turbine systems enables engine designs with higher inlet temperatures, thus improving the engine efficiency, power density and reliability. The impact and erosion resistance of turbine thermal barrier coating systems are crucial to the turbine coating technology application, because a robust turbine blade TBC system is a prerequisite for fully utilizing the potential coating technology benefit in the rotorcraft propulsion. This paper describes the turbine blade TBC development in addressing the coating impact and erosion resistance. Advanced thermal barrier coating systems with improved performance have also been validated in laboratory simulated engine erosion and/or thermal gradient environments. A preliminary life prediction modeling approach to emphasize the turbine blade coating erosion is also presented.

  3. Application of Plasma Spraying as a Precursor in the Synthesis of Oxidation-Resistant Coatings

    NASA Astrophysics Data System (ADS)

    Ritt, P.; Lu-Steffes, O.; Sakidja, R.; Perepezko, J. H.; Lenling, W.; Crawmer, D.; Beske, J.

    2013-08-01

    Thermal spray methods offer a versatile and flexible approach to the manufacture of coatings as a final product. A novel application of thermal spray coating is demonstrated by incorporating a plasma-sprayed Mo layer coating as a precursor step within an integrated costing design. The effectiveness of the two-step design is illustrated for aluminoborosilica coatings on SiC/C composites and W substrates based on the plasma-sprayed Mo precursor and subsequent codeposition of Si and B by a pack cementation method. Even with incomplete precursor coverage, an aluminoborosilica coating is developed because of the high initial fluidity of the as-pack coating. An effective oxidation resistance is observed following exposure at elevated temperatures (1373-1673 K) in ambient air and during torch testing at 1773 K, providing clear evidence that the plasma spraying of Mo is a viable precursor step in the formation of the oxidation-resistant Mo-Si-B-based coating.

  4. Hexagonal Boron Nitride Nanosheets as High-Performance Binder-Free Fire-Resistant Wood Coatings.

    PubMed

    Liu, Juanjuan; Kutty, Rajendrannair Govindan; Zheng, Qingshen; Eswariah, Varrla; Sreejith, Sivaramapanicker; Liu, Zheng

    2017-01-01

    Hexagonal boron nitride (h-BN) nanosheets are synthesized through a facile shear force liquid phase exfoliation method and their use as a binder-free oxidation and fire-resistant wood coating is demonstrated. Characterized by intrinsic low thermal diffusivity and thermal effusivity, h-BN nanosheet coatings show an excellent fire resistance and oxidation resistance up to 900 °C in air.

  5. 2D Heterostructure coatings of hBN-MoS2 layers for corrosion resistance

    NASA Astrophysics Data System (ADS)

    Vandana, Sajith; Kochat, Vidya; Lee, Jonghoon; Varshney, Vikas; Yazdi, Sadegh; Shen, Jianfeng; Kosolwattana, Suppanat; Vinod, Soumya; Vajtai, Robert; Roy, Ajit K.; Sekhar Tiwary, Chandra; Ajayan, P. M.

    2017-02-01

    Heterostructures of atomically thin 2D materials could have improved physical, mechanical and chemical properties as compared to its individual components. Here we report, the effect of heterostructure coatings of hBN and MoS2 on the corrosion behavior as compared to coatings employing the individual 2D layer compositions. The poor corrosion resistance of MoS2 (widely used as wear resistant coating) can be improved by incorporating hBN sheets. Depending on the atomic stacking of the 2D sheets, we can further engineer the corrosion resistance properties of these coatings. A detailed spectroscopy and microscopy analysis has been used to characterize the different combinations of layered coatings. Detailed DFT based calculation reveals that the effect on the electrical properties due to atomic stacking is one of the major reasons for the improvement seen in corrosion resistance.

  6. The Effect of Coating Thickness on Corrosion Resistance of Hydroxyapatite Coated Ti6Al4V and 316L SS Implants

    NASA Astrophysics Data System (ADS)

    Aksakal, B.; Gavgali, M.; Dikici, B.

    2010-08-01

    Hydroxyapatite (HAP) has been coated onto Ti6Al4V and 316L SS substrates by sol-gel method. The coating thicknesses for the analysis were about 40 and 72 μm. Adhesion and corrosion tests have been conducted on uncoated and HAP-coated substrates. The coatings were characterized by XRD, SEM, and adhesion analysis. The corrosion resistance was examined in vitro by potentiodynamic polarization technique in Ringer’s solution at room temperature. Electrochemical analysis indicated that the highest corrosion susceptibility was found on 72-μm-coated 316L SS, and the 40-μm HAP-coated Ti6Al4V showed the highest corrosion resistance. It was observed that the coating thickness was an effective parameter on both adhesion and corrosion resistance. It was shown that adhesion and corrosion resistance decreased with increasing coating thickness on both substrates.

  7. Development of wear-resistant coatings for cobalt-base alloys

    SciTech Connect

    Cockeram, B.V.

    1999-03-01

    The costs and hazards resulting from nuclear plant radiation exposure with activated cobalt wear debris could potentially be reduced by covering the cobalt-base materials with a wear resistant coating. However, the hardnesses of many cobalt-base wear alloys are significantly lower than conventional PVD hard coatings, and mechanical support of the hard coating is a concern. Four approaches have been taken to minimize the hardness differences between the substrate and PVD hard coating: (1) use a thin Cr-nitride hard coating with layers that are graded with respect to hardness, (2) use a thicker, multilayered coating (Cr-nitride or Zr-nitride) with graded layers, (3) use nitriding to harden the alloy subsurface followed by application of a multilayered coating of Cr-nitride, and (4) use of nitriding alone. Since little work has been done on application of PVD hard coatings to cobalt-base alloys, some details on process development and characterization of the coatings is presented. Scratch testing was used to evaluate the adhesion of the different coatings. A bench-top rolling contact test was used to evaluate the wear resistance of the coatings. The test results are discussed, and the more desirable coating approaches are identified.

  8. Fluorocarbon compounds in MRI diagnostics and medical therapy

    NASA Astrophysics Data System (ADS)

    Pirogov, Yu

    2016-02-01

    The lecture describes the application of fluorocarbon compounds as blood substitutes and contrasting preparations in MRI diagnostics. A blood substitute product fluorocarbon Perfluorane® has shown effectiveness in oxygen delivery to the tissues of living organisms, and cardioprotective effect which does not depend on the patient's blood group. Inclusion of paramagnetic atoms (gadolinium, iron, etc.) to the Perfluorane® chemical formula creates a new compound with high MRI contrast efficiencies at Larmor frequencies of protons so and fluorine-19 nuclei.

  9. Fluorinated diamond particles bonded in a filled fluorocarbon resin matrix

    DOEpatents

    Taylor, G.W.; Roybal, H.E.

    1983-11-14

    A method of producing fluorinated diamond particles bonded in a filled fluorocarbon resin matrix. Simple hot pressing techniques permit the formation of such matrices from which diamond impregnated grinding tools and other articles of manufacture can be produced. Teflon fluorocarbon resins filled with Al/sub 2/O/sub 3/ yield grinding tools with substantially improved work-to-wear ratios over grinding wheels known in the art.

  10. Fluorinated diamond particles bonded in a filled fluorocarbon resin matrix

    DOEpatents

    Taylor, Gene W.; Roybal, Herman E.

    1985-01-01

    A method of producing fluorinated diamond particles bonded in a filled fluorocarbon resin matrix. Simple hot pressing techniques permit the formation of such matrices from which diamond impregnated grinding tools and other articles of manufacture can be produced. Teflon fluorocarbon resins filled with Al.sub.2 O.sub.3 yield grinding tools with substantially improved work-to-wear ratios over grinding wheels known in the art.

  11. Thermodynamic properties of gaseous fluorocarbons and isentropic equilibrium expansions of two binary mixtures of fluorocarbons and argon

    NASA Technical Reports Server (NTRS)

    Talcott, N. A., Jr.

    1977-01-01

    Equations and computer code are given for the thermodynamic properties of gaseous fluorocarbons in chemical equilibrium. In addition, isentropic equilibrium expansions of two binary mixtures of fluorocarbons and argon are included. The computer code calculates the equilibrium thermodynamic properties and, in some cases, the transport properties for the following fluorocarbons: CCl2F, CCl2F2, CBrF3, CF4, CHCl2F, CHF3, CCL2F-CCl2F, CCLF2-CClF2, CF3-CF3, and C4F8. Equilibrium thermodynamic properties are tabulated for six of the fluorocarbons(CCl3F, CCL2F2, CBrF3, CF4, CF3-CF3, and C4F8) and pressure-enthalpy diagrams are presented for CBrF3.

  12. Plasma treatment of thin film coated with graphene flakes for the reduction of sheet resistance.

    PubMed

    Kim, Sung Hee; Oh, Jong Sik; Kim, Kyong Nam; Seo, Jin Seok; Jeon, Min Hwan; Yang, Kyung Chae; Yeom, Geun Young

    2013-12-01

    We investigated the effects of plasma treatment on the sheet resistance of thin films spray-coated with graphene flakes on polyethylene terephthalate (PET) substrates. Thin films coated with graphene flakes show high sheet resistance due to defects within graphene edges, domains, and residual oxygen content. Cl2 plasma treatment led to decreased sheet resistance when treatment time was increased, but when thin films were treated for too long the sheet resistance increased again. Optimum treatment time was related to film thickness. The reduction of sheet resistance may be explained by the donation of holes due to forming pi-type covalent bonds of Cl with carbon atoms on graphene surfaces, or by C--Cl bonding at the sites of graphene defects. However, due to radiation damage caused by plasma treatment, sheet resistance increased with increased treatment time. We found that the sheet resistance of PET film coated with graphene flakes could be decreased by 50% under optimum conditions.

  13. High temperature ceramic articles having corrosion resistant coating

    DOEpatents

    Stinton, David P.; Lee, Woo Y.

    1997-01-01

    A ceramic article which includes a porous body of SiC fibers, Si.sub.3 N.sub.4 fibers, SiC coated fibers or Si.sub.3 N.sub.4 coated fibers, having at least one surface, the article having a coating of AlN adherently disposed throughout at least a portion of the porous body.

  14. Microstructure and Corrosion Resistance of Electrodeposited Ni-Cu-Mo Alloy Coatings

    NASA Astrophysics Data System (ADS)

    Meng, Xinjing; Shi, Xi; Zhong, Qingdong; Shu, Mingyong; Xu, Guanquan

    2016-11-01

    This paper deals with the electrodeposition of Ni-Cu-Mo ternary alloy coatings on low-carbon steel substrate from an aqueous citrate sulfate bath. The structures and microstructure of coatings were characterized by scanning electron microscopy and x-ray diffractometry. The corrosion resistance of coatings was investigated by potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy techniques. The results show that the Ni-Cu-Mo coatings are mainly composed of fcc-Ni phase and a small amount of NiCu phase. Ni-Cu-Mo coatings exhibit a nodular surface morphology, and the roughness of electroplated coating increases with the increasing of Na2MoO4·2H2O in the bath. The corrosion performance of the coatings is significantly affected by the Mo content of the alloy coating and their surface morphology. The coating prepared in bath containing 40 g/L Na2MoO4·2H2O has the highest corrosion resistance in 3.5 wt.% NaCl solution, while that prepared in bath containing 60 g/L (or more) Na2MoO4·2H2O shows a lower corrosion resistance due to the presence of microcracks on the coating surface.

  15. Thermal-electrical properties and resistance stability of silver coated yarns

    NASA Astrophysics Data System (ADS)

    Li, Yafang; Liu, Hao; Li, Xiaojiu

    2017-03-01

    Thermal-electrical properties and resistance stability of silver yarns was researched to evaluate the performance be a heating element. Three samples of silver coated yarns with different linear density and electrical resistivity, which obtained by market. Silver coated yarns were placed at the high temperature condition for ageing. The electrical resistances of yarns were increased with the ageing process. The infrared photography instrument was used to measurement the temperature variation of silver coated yarns by applied different current on. The result shows that the temperature rise with the power increases.

  16. Nano Structured Plasma Spray Coating for Wear and High Temperature Corrosion Resistance Applications

    NASA Astrophysics Data System (ADS)

    Ghosh, D.; Shukla, A. K.; Roy, H.

    2014-04-01

    The nano structured coating is a major challenge today to improve the different mechanical properties, wear and high temperature corrosion resistance behaviour of different industrial alloys. This paper is a review on synthesis of nano powder, plasma spraying methods, techniques of nano structured coating by plasma spray method, mechanical properties, tribological properties and high temperature corrosion behaviour of nano structured coating. Nano structured coatings of ceramic powders/composites are being developed for wide variety of applications like boiler, turbine and aerospace industries, which requires the resistance against wear, corrosion, erosion etc. The nano sized powders are subjected to agglomeration by spray drying, after which nano structured coating can be successfully applied over the substrate. Nano structured coating shows improved mechanical wear resistance and high temperature corrosion resistance. The significant improvement of wear and corrosion resistance is mainly attributed to formation of semi molten nano zones in case of nano structured coatings. The future scope of application of nano structured coating has also been highlighted in this paper.

  17. Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof

    DOEpatents

    Sarin, V.K.

    1990-08-21

    An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications is disclosed. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al[sub x]N[sub y]O[sub z] layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al[sub x]N[sub y]O[sub z] layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

  18. Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof

    DOEpatents

    Sarin, Vinod K.

    1990-01-01

    An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al.sub.x N.sub.y O.sub.z layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al.sub.x N.sub.y O.sub.z layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

  19. NASA Glenn/AADC-Rolls Royce Collaborated to Measure Erosion Resistance on Coated Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Sutter, James K.; Mondry, Richard; Ma, Kong; Horan, Dick; Naik, Subhash; Cupp, Randall

    2003-01-01

    Polymer matrix composites (PMCs) are increasingly used in aerospace and automotive applications because of their light weight and high strength-to-weight ratio relative to metals. However, a major drawback of PMCs is poor abrasion resistance, which restricts their use, especially at high temperatures. Simply applying a hard coating on PMCs to improve abrasion and erosion resistance is not effective since coating durability is short lived (ref. 1). Generally, PMCs have higher coefficients of thermal expansion than metallic or ceramic coatings have, and coating adhesion suffers because of poor interfacial adhesion strength. One technique commonly used to improve coating adhesion or durability is the use of bond coats that are interleaved between a coating and a substrate with vastly different coefficients of thermal expansion. An example of this remedy is the use of bondcoats for ceramic thermal barrier coatings on metallic turbine components (ref. 2). Prior collaborative research between the NASA Glenn Research Center and the Allison Advanced Development Company (AADC) demonstrated that bond coats sandwiched between PMCs and high-quality plasma-sprayed, erosion-resistant coatings substantially improved the erosion resistance of PMCs (ref. 3). One unresolved problem in this earlier collaboration was that there was no easy, accurate way to measure the coating erosion wear scar. Coating wear was determined by both profilometry and optical microscopy. Both techniques are time consuming. Wear measurement by optical microscopy requires sample destruction and does not provide a comprehensive measure of the entire wear volume. An even more subtle, yet critical, problem is that these erosion coatings contain two or more materials with different densities. Therefore, simply measuring specimen mass loss before and after erosion will not provide an accurate gauge for coating and/or substrate volume loss. By using a noncontact technique called scanning optical interferometry

  20. Selected fretting-wear-resistant coatings for Ti-6 pct Al-4 pct V alloy

    NASA Technical Reports Server (NTRS)

    Bill, R. C.

    1985-01-01

    The ability of several wear-resistant coatings to reduce fretting in the Ti-6Al-4V alloy is investigated. The experimental apparatus and procedures for evaluating fretting in uncoated Ti-6Al-4V alloy and in the alloy with plasma-sprayed coatings, polymer-bonded coating, and surface treatments are described. The wear volume and wear rate for the alloys are measured and compared. It is concluded that Al2O3 with 13 percent TiO2, preoxidation and nitride surface treatments, and MoS2 sputtering result in wear-resistant surfaces; however, the polyimide coating is the most wear resistant coating in both dry and moist air, and it causes the least wear to the uncoated alloy surface.

  1. Development of wear-resistant coatings for cobalt-base alloys

    SciTech Connect

    Cockeram, B.V.

    1999-10-22

    The level of nuclear plant radiation exposure due to activated cobalt wear debris could potentially be reduced by covering the cobalt-base materials with a wear resistant coating. Laboratory pin-on-disc and rolling contact wear tests were used to evaluate the wear performance of several coatings. Based on the results of these tests, multilayer Cr-nitride coatings and ion nitriding are the most promising approaches.

  2. Complex, Precision Cast Columbium Alloy Gas Turbine Engine Nozzles Coated to Resist Oxidation.

    DTIC Science & Technology

    1980-04-01

    that afforded by CbSi2 alloy, the surface was modified by depositing an overlay coating that can be silicided to form a stable silicon rich layer which...stage process. Chromium and titanium were codeposited and were sub- sequently silicided . The resulting coating composition was much lower in columbium... coating and to maximize the elements that form outstanding oxidation-resistant silicides . In the Solar process, the slurry of the metallic modifier is

  3. Nano-coatings on carbon structures for interfacial modification

    NASA Astrophysics Data System (ADS)

    Pulikollu, Rajasekhar V.

    damages the ligaments and cell walls of carbon foam. This results in higher elastic modulus but lower strength. So, to get any benefit from such approaches the optimization window may be very narrow and marginal in controllability. An alternative solution would be to synthesize ultra thin film coatings without etching the surfaces. It is observed that plasma assisted coatings having thickness in the range of few nanometers (4-5nm) are completely covering the graphite substrates. The coating surface chemistry and morphology information is based upon XPS and AFM studies on pyrolytic graphite substrate. Two types of plasma surface modification techniques have been attempted: one is to make the surface more reactive for structural components and the other is to make the surface more inert for stand-alone structures. In order to achieve these goals plasma assisted oxide and fluorocarbon coatings are studied in detail. The synthesized oxide and fluorocarbon coating chemistries are comparable to conventional silica (SiO2) and polytetrafluoroethylene (PTFE, -CF2-). It is seen that the fluorocarbon coatings provide moisture resistance to graphitic foam by making the surface inert at the nanometer scale. On the other hand, plasma assisted oxide coating is a feasible and effective means of improving the wettability and dispersion of foam and nanofibers in organic polymer matrix material. Surface analysis as well as microstructural studies and mechanical tests have shown encouraging results. The interface reactions between graphite (coated and uncoated) and epoxy have also been studied in detail. Nano-scale plasma coatings have also been applied for metal matrix composites and semiconductor related applications. The fluorocarbon coating promote delamination/exfoliation of the metal on graphite, hence may be used for patterning or lithography. Oxide coatings seem to enhance the adhesion and metallic diffusion between graphite and metal, hence can be used for the development of metal

  4. Properties of solid polymer electrolyte fluorocarbon film. [used in hydrogen/oxygen fuel cells

    NASA Technical Reports Server (NTRS)

    Alston, W. B.

    1973-01-01

    The ionic fluorocarbon film used as the solid polymer electrolyte in hydrogen/oxygen fuel cells was found to exhibit delamination failures. Polarized light microscopy of as-received film showed a lined region at the center of the film thickness. It is shown that these lines were not caused by incomplete saponification but probably resulted from the film extrusion process. The film lines could be removed by an annealing process. Chemical, physical, and tensile tests showed that annealing improved or sustained the water contents, spectral properties, thermo-oxidative stability, and tensile properties of the film. The resistivity of the film was significantly decreased by the annealing process.

  5. The Bacillus subtilis spore coat provides "eat resistance" during phagocytic predation by the protozoan Tetrahymena thermophila.

    PubMed

    Klobutcher, Lawrence A; Ragkousi, Katerina; Setlow, Peter

    2006-01-03

    Bacillus spores are highly resistant to many environmental stresses, owing in part to the presence of multiple "extracellular" layers. Although the role of some of these extracellular layers in resistance to particular stresses is known, the function of one of the outermost layers, the spore coat, is not completely understood. This study sought to determine whether the spore coat plays a role in resistance to predation by the ciliated protozoan Tetrahymena, which uses phagocytosis to ingest and degrade other microorganisms. Wild-type dormant spores of Bacillus subtilis were efficiently ingested by the protozoan Tetrahymena thermophila but were neither digested nor killed. However, spores with various coat defects were killed and digested, leaving only an outer shell termed a rind, and supporting the growth of Tetrahymena. A similar rind was generated when coat-defective spores were treated with lysozyme alone. The sensitivity of spores with different coat defects to predation by T. thermophila paralleled the spores' sensitivities to lysozyme. Spore killing by T. thermophila was by means of lytic enzymes within the protozoal phagosome, not by initial spore germination followed by killing. These findings suggest that a major function of the coat of spores of Bacillus species is to protect spores against predation. We also found that indigestible rinds were generated even from spores in which cross-linking of coat proteins was greatly reduced, implying the existence of a coat structure that is highly resistant to degradative enzymes.

  6. Impact of substrate surface scratches on the laser damage resistance of multilayer coatings

    SciTech Connect

    Qiu, S; Wolfe, J; Monterrosa, A; Teslich, N; Feit, M; Pistor, T; Stolz, C

    2010-11-03

    Substrate scratches can limit the laser resistance of multilayer mirror coatings on high-peak-power laser systems. To date, the mechanism by which substrate surface defects affect the performance of coating layers under high power laser irradiation is not well defined. In this study, we combine experimental approaches with theoretical simulations to delineate the correlation between laser damage resistance of coating layers and the physical properties of the substrate surface defects including scratches. A focused ion beam technique is used to reveal the morphological evolution of coating layers on surface scratches. Preliminary results show that coating layers initially follow the trench morphology on the substrate surface, and as the thickness increases, gradually overcoat voids and planarize the surface. Simulations of the electrical-field distribution of the defective layers using the finite-difference time-domain (FDTD) method show that field intensification exists mostly near the top surface region of the coating near convex focusing structures. The light intensification could be responsible for the reduced damage threshold. Damage testing under 1064 nm, 3 ns laser irradiation over coating layers on substrates with designed scratches show that damage probability and threshold of the multilayer depend on substrate scratch density and width. Our preliminary results show that damage occurs on the region of the coating where substrate scratches reside and etching of the substrate before coating does not seem to improve the laser damage resistance.

  7. Corrosion resistance and cytocompatibility of biodegradable surgical magnesium alloy coated with hydrogenated amorphous silicon.

    PubMed

    Xin, Yunchang; Jiang, Jiang; Huo, Kaifu; Tang, Guoyi; Tian, Xiubo; Chu, Paul K

    2009-06-01

    The fast degradation rates in the physiological environment constitute the main limitation for the applications of surgical magnesium alloys as biodegradable hard-tissue implants. In this work, a stable and dense hydrogenated amorphous silicon coating (a-Si:H) with desirable bioactivity is deposited on AZ91 magnesium alloy using magnetron sputtering deposition. Raman spectroscopy and Fourier transform infrared spectroscopy reveal that the coating is mainly composed of hydrogenated amorphous silicon. The hardness of the coated alloy is enhanced significantly and the coating is quite hydrophilic as well. Potentiodynamic polarization results show that the corrosion resistance of the coated alloy is enhanced dramatically. In addition, the deterioration process of the coating in simulated body fluids is systematically investigated by open circuit potential evolution and electrochemical impedance spectroscopy. The cytocompatibility of the coated Mg is evaluated for the first time using hFOB1.19 cells and favorable biocompatibility is observed.

  8. Tribological properties, corrosion resistance and biocompatibility of magnetron sputtered titanium-amorphous carbon coatings

    NASA Astrophysics Data System (ADS)

    Dhandapani, Vishnu Shankar; Subbiah, Ramesh; Thangavel, Elangovan; Arumugam, Madhankumar; Park, Kwideok; Gasem, Zuhair M.; Veeraragavan, Veeravazhuthi; Kim, Dae-Eun

    2016-05-01

    Amorphous carbon incorporated with titanium (a-C:Ti) was coated on 316L stainless steel (SS) by magnetron sputtering technique to attain superior tribological properties, corrosion resistance and biocompatibility. The morphology, topography and functional groups of the nanostructured a-C:Ti coatings in various concentrations were analyzed using atomic force microscopy (AFM), Raman, X-Ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Raman and XPS analyses confirmed the increase in sp2 bonds with increasing titanium content in the a-C matrix. TEM analysis confirmed the composite nature of the coating and the presence of nanostructured TiC for Ti content of 2.33 at.%. This coating showed superior tribological properties compared to the other a-C:Ti coatings. Furthermore, electrochemical corrosion studies were performed against stimulated body fluid medium in which all the a-C:Ti coatings showed improved corrosion resistance than the pure a-C coating. Preosteoblasts proliferation and viability on the specimens were tested and the results showed that a-C:Ti coatings with relatively high Ti (3.77 at.%) content had better biocompatibility. Based on the results of this work, highly durable coatings with good biocompatibility could be achieved by incorporation of optimum amount of Ti in a-C coatings deposited on SS by magnetron sputtering technique.

  9. Cellulose acetate/hydroxyapatite/chitosan coatings for improved corrosion resistance and bioactivity.

    PubMed

    Zhong, Zhenyu; Qin, Jinli; Ma, Jun

    2015-04-01

    Cellulose acetate (CA) nanofibers were deposited on stainless steel plates by electrospinning technique. The composite of hydroxyapatite (HAP) nanoparticles and chitosan (CHI) was coated subsequently by dip-coating. The structure and morphology of the obtained coatings were investigated by Fourier transform infrared spectroscopy and scanning electron microscopy. The stability of the coatings in physiological environment was studied using electrochemical polarization and impedance spectroscopy. The CA nanofibers were embedded in the HAP/CHI coating and the resulted composite film was densely packed and uniform on the substrate. The in vitro biomineralization study of the coated samples immersed in simulated body fluid (SBF) confirmed the formation ability of bone-like apatite layer on the surface of HAP-containing coatings. Furthermore, the coatings could provide corrosion resistance to the stainless steel substrate in SBF. The electrochemical results suggested that the incorporation of CA nanofibers could improve the corrosion resistance of the HAP/CHI coating. Thus, biocompatible CA/HAP/CHI coated metallic implants could be very useful in the long-term stability of the biomedical applications.

  10. Modification of aluminide coating with yttrium for improved resistance to corrosive erosion

    SciTech Connect

    Zhang, T.; Luo, Y.; Li, D.Y.

    1999-12-01

    Aluminide coatings on a mild steel substrate were modified by using an oxygen-active element, yttrium, for improved resistance to corrosive erosion. The performance of the yttrium-containing coating during the following three erosion conditions was evaluated: dry sand erosion at different temperatures, erosion in a dilute NaCl slurry containing 30% silica sand, and erosion in a dilute H{sub 2}SO{sub 4} slurry containing 30% silica sand. Results of the study demonstrated that yttrium significantly improved the resistance of the aluminide coating to both corrosive erosion and dry sand erosion.

  11. Titanium Carbides Coatings for Wear Resistant Biomedical Devices: Manufacturing and Modeling

    SciTech Connect

    Contro, R.; Vena, P.; Gastaldi, D.; Masante, S.; Cavallotti, P. L.; Nobili, L.; Bestetti, M.

    2008-02-15

    Deposition of Titanium Carbide coatings on Ti6Al4V substrate, through the reactive magnetron sputtering technique is here presented. The mechanical characterization of the coatings has been carried out through a set of indentation tests at different maximum applied loads. The elastic stiffness as well as the hardness of the coating-substrate system indicate that these coatings are suitable candidates for wear resistance applications in the orthopaedic field. Numerical simulation of the indentation tests allowed the identification of the constitutive parameters of the titanium carbide. Good agreement was achieved between experimental and numerical results.

  12. Characterization, mechanical properties and corrosion resistance of biocompatible Zn-HA/TiO2 nanocomposite coatings.

    PubMed

    Mirak, Mohammad; Alizadeh, Morteza; Ghaffari, Mohammad; Ashtiani, Mohammad Najafi

    2016-09-01

    Biocompatible Zinc-hydroxyapatite-titania and Zinc-hydroxyapatite nanocomposite coatings have been prepared by electrodeposition on NiTi shape memory alloy. Structures of coatings were characterized using X-ray diffraction (XRD). It was found that addition of TiO2 particles cause to reduction of crystallite size of coating. Scanning Electronic Microscope (SEM) observation showed that the Zn-HA/TiO2 coating consists of plate-like regions which can express that this plate-like structure can facilitate bone growth. X-ray photoelectron microscope (XPS) was performed to investigation of chemical state of composite coating and showed that Zinc matrix was bonded to oxygen. high-resolution transmission electron microscope (HRTEM) result illustrated the crystalline structure of nanocomposite coating. Mechanical behavior of coating was evaluated using microhardness and ball on disk wear test. The TiO2 incorporated composite coatings exhibited the better hardness and anti-wear performance than the Zn-HA coatings. Polarization measurements have been used to evaluate the electrochemical coatings performance. The Zn-HA/TiO2 composite coatings showed the highest corrosion resistance compared with Zn-HA and bare NiTi.

  13. Oxidation resistance of aluminum-coated Fe-20Cr alloys containing rare earths or yttrium

    SciTech Connect

    Sigler, D.R. )

    1993-10-01

    Aluminum-coated Fe-20Cr (rare earth or yttrium) alloy foils were developed with oxidation resistance equivalent or superior to Fe-20Cr-5Al (rare earth or yttrium) alloy foils. The coated foils were made by dipping Fe-20Cr sheet into a salt-covered aluminum bath and then rolling the sheet to foil. Oxidation resistance of the coated foil was enhanced by adding rare earths or yttrium to the Fe-20Cr substrate alloys to insure oxide adherence. Test results indicate that only sufficient addition to tie up sulfur as a stable sulfide is needed in the Fe-20Cr alloy. Aluminum-coated foils show lower oxide growth rates than similar Fe-Cr-Al alloys, most likely the result of fewer impurities (particularly Fe) is the coated foils' growing oxide scale. 31 refs., 18 figs., 2 tabs.

  14. Method for improving the oxidation-resistance of metal substrates coated with thermal barrier coatings

    DOEpatents

    Thompson, Anthony Mark; Gray, Dennis Michael; Jackson, Melvin Robert

    2002-01-01

    A method for providing a protective coating on a metal-based substrate is disclosed. The method involves the application of an aluminum-rich mixture to the substrate to form a discontinuous layer of aluminum-rich particles, followed by the application of a second coating over the discontinuous layer of aluminum-rich particles. Aluminum diffuses from the aluminum-rich layer into the substrate, and into any bond coat layer which is subsequently applied. Related articles are also described.

  15. Preparation, antibacterial effects and corrosion resistant of porous Cu-TiO2 coatings

    NASA Astrophysics Data System (ADS)

    Wu, Haibo; Zhang, Xiangyu; Geng, Zhenhua; Yin, Yan; Hang, Ruiqiang; Huang, Xiaobo; Yao, Xiaohong; Tang, Bin

    2014-07-01

    Antibacterial TiO2 coatings with different concentrations of Cu (Cu-TiO2) were prepared by micro-arc oxidation (MAO) on pre-sputtered CuTi films. The effect of Cu concentrations in CuTi films on the MAO process was investigated. The Cu-TiO2 coatings were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The corrosion resistance of Cu-TiO2 coatings was evaluated via potentiodynamic polarization method. The antibacterial properties were assessed by two methods: spread plate method and fluorescence staining. The experimental results demonstrate that the coatings are porous and consist of anatase phase, rutile phase and unoxidized titanium. The CuTi films are almost completely oxidized and the thickness of all MAO coatings is about 5-10 μm. Cu mainly exists as CuO in the TiO2 coatings. The Cu-TiO2 coatings exhibit excellent antibacterial activities, and the antibacterial rate gradually rise with the increase in Cu concentration in the MAO coatings. The corrosion resistance of MAO coatings is also improved slightly.

  16. Nanocomposite coatings on biomedical grade stainless steel for improved corrosion resistance and biocompatibility.

    PubMed

    Nagarajan, Srinivasan; Mohana, Marimuthu; Sudhagar, Pitchaimuthu; Raman, Vedarajan; Nishimura, Toshiyasu; Kim, Sanghyo; Kang, Yong Soo; Rajendran, Nallaiyan

    2012-10-24

    The 316 L stainless steel is one of the most commonly available commercial implant materials with a few limitations in its ease of biocompatibility and long-standing performance. Hence, porous TiO(2)/ZrO(2) nanocomposite coated over 316 L stainless steels was studied for their enhanced performance in terms of its biocompatibility and corrosion resistance, following a sol-gel process via dip-coating technique. The surface composition and porosity texture was studied to be uniform on the substrate. Biocompatibility studies on the TiO(2)/ZrO(2) nanocomposite coatings were investigated by placing the coated substrate in a simulated body fluid (SBF). The immersion procedure resulted in the complete coverage of the TiO(2)/ZrO(2) nanocomposite (coated on the surface of 316 L stainless steel) with the growth of a one-dimensional (1D) rod-like carbonate-containing apatite. The TiO(2)/ZrO(2) nanocomposite coated specimens showed a higher corrosion resistance in the SBF solution with an enhanced biocompatibility, surpassing the performance of the pure oxide coatings. The cell viability of TiO(2)/ZrO(2) nanocomposite coated implant surface was examined under human dermal fibroblasts culture, and it was observed that the composite coating enhances the proliferation through effective cellular attachment compared to pristine 316 L SS surface.

  17. Ablation Resistance of C/C Composites with Atmospheric Plasma-Sprayed W Coating

    NASA Astrophysics Data System (ADS)

    Zhou, Zhe; Wang, Yuan; Gong, Jieming; Ge, Yicheng; Peng, Ke; Ran, Liping; Yi, Maozhong

    2016-12-01

    To improve the ablation resistance of carbon/carbon (C/C) composites, tungsten (W) coating with thickness of 1.2 mm was applied by atmospheric plasma spraying. The antiablation property of the coated composites was evaluated by oxyacetylene flame ablation experiments. The phase composition of the coating was investigated by a combination of x-ray diffraction analysis and scanning electron microscopy with energy-dispersive x-ray spectroscopy analysis. The ablation resistance of the coated C/C substrates was compared with that of uncoated C/C composites and C/C-CuZr composites after ablation for 30 s. The properties of the coated C/C composites after ablation time of 10, 30, 60, 90, 120, and 180 s were further studied. The results indicated that the mass and linear ablation rates of the W-coated C/C composites were lower than those of uncoated C/C or C/C-CuZr composites after ablation for 30 s. The coating exhibited heat stability after 120 s of ablation, with mass loss and linear ablation rates of 7.39 × 10-3 g/s and 3.50 × 10-3 mm/s, respectively. However, the W coating became ineffective and failed after ablation for 180 s. Three ablation regions could be identified, in which the ablation mechanism of the coating changed from thermochemical to thermophysical erosion to mechanical scouring with increasing ablation time.

  18. The corrosion resistance and neutron-absorbing properties of coatings based on amorphous alloys

    NASA Astrophysics Data System (ADS)

    Sevryukov, O. N.; Polyansky, A. A.

    2016-04-01

    The object of the present study was the corrosion-resistant amorphizing alloys with an increased content of boron for cladding the surface of metals, rapidly quenched alloys without boron for protective coatings on a high-boron cladding layer, as well as steel samples with a protective coating with a high content of boron and without boron. The aim of the work is to investigate the corrosion resistance of a coating in water at the temperature of 40 °C in conditions of an open access of oxygen for 1000 h, as well as the features of the microstructure of clad samples before and after the corrosion tests. New data on the corrosion resistance of Cr18Ni10Ti steel samples with a protective layer from a rapidly quenched alloy Ni-19Cr-10Si (in wt.%) on a high-boron coating have been obtained.

  19. The impact of coating architecture on the hardness, friction and wear resistance of hard and tribological nanocomposite coatings

    NASA Astrophysics Data System (ADS)

    Endrino, Jose Luis

    Future generations of mechanical systems will place new demands on the tribological performance of interacting surfaces. Vapor-deposited surface coatings can provide extended lifetimes, increased efficiencies and energy savings for mechanical components and tools. These benefits can also be extended to space mechanisms and satellites with the use of vacuum solid lubricants. The material properties of surface coatings such as hardness, friction, and wear resistance in a particular environment are influenced by the characteristics of the coating microstructure which include density, grain size, grain boundary chemistry, porosity, and grain orientation. In this research effort bias sputter deposition, co-sputtering, and magnetron sputtering-pulsed laser deposition are used to deposit and control the formation of composite coating architectures. The developed microstructures were studied by x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Mechanical and tribological tests included nanoindentation and pin-on-disk. Results were analyzed in relation to the coatings' chemical composition and microstructure with the objective of establishing structure-property relations for these films. Hard coatings presented in this thesis include carbides that form a solid solution (Ti-Hf-C) as well as carbides that form composite microstructures (WC-SiC, HfC-SiC). Hardness measurements on these films indicated the potential of transition metal carbide-silicon carbide composites to be utilized as protective coatings. With the use of a substrate bias potential, a hardness of over 35 GPa was achieved for some HfC-SiC samples. By co-depositing from carbide and silver targets, composite tribological coatings (e.g. SiC-Ag, WC-Ag, TiC-Ag, HfC-Ag) were developed. These systems revealed how critical materials selection can be in the determination of a coating's architecture, and how carbide-silver films can be used to provide low friction

  20. Mechanical and corrosion resistance properties of TiO2 nanoparticles reinforced Ni coating by electrodeposition

    NASA Astrophysics Data System (ADS)

    Shao, W.; Nabb, D.; Renevier, N.; Sherrington, I.; Luo, J. K.

    2012-09-01

    Coatings have been widely used in engineering and decoration to protect components and products and enhance their life span. Nickel (Ni) is one of the most important hard coatings. Improvement in its tribological and mechanical properties would greatly enhance its use in industry. Nanocomposite coatings of metals with various reinforced nanoparticles have been developed in last few decades. Titania (TiO2) exhibit excellent mechanical properties. It is believed that TiO2 incorporation in Ni matrix will improve the properties of Ni coatings significantly. The main purpose of the current work is to investigate the mechanical and anti-corrosion properties of the electroplated nickel nanocomposite with a small percentage of TiO2. The surface morphology of nanocomposite coating was characterized by scanning electron microscopy (SEM). The hardness of the nanocoating was carried out using micromaterials nanoplatform. The sliding wear rate of the coating at room temperature in dry condition was assessed by a reciprocating ball-on-disk computer-controlled oscillating tribotester. The results showed the nanocomposite coatings have a smoother and more compact surface than the pure Ni layer and have higher hardness and lower wear rate than the pure Ni coating. The anti-corrosion property of nanocomposite coating was carried out in 3.5% NaCl and high concentrated 35% NaCl solution, respectively. The results also showed that the nanocomposite coating improves the corrosion resistance significantly. This present work reveals that incorporation of TiO2 in nickel nanocomposite coating can achieve improved corrosion resistance and mechanical properties of both hardness and wear resistance performances, and the improvement becomes stronger as the content of TiO2 is increased.

  1. The effect of polar end of long-chain fluorocarbon oligomers in promoting the superamphiphobic property over multi-scale rough Al alloy surfaces

    NASA Astrophysics Data System (ADS)

    Saifaldeen, Zubayda S.; Khedir, Khedir R.; Camci, Merve T.; Ucar, Ahmet; Suzer, Sefik; Karabacak, Tansel

    2016-08-01

    Rough structures with re-entrant property and their subsequent surface energy reduction with long-chain fluorocarbon oligomers are both critical in developing superamphiphobic (SAP, i.e. both super hydrophobic and superoleophobic) surfaces. However, morphology of the low-surface energy layer on a rough re-entrant substrate can strongly depend on the fluorocarbon oligomers used. In this study, the effect of polar end of different kinds of long-chain fluorocarbon oligomers in promoting a self-assembled monolayer with close packed molecules and robust adhesion on multi-scale rough Al alloy surfaces was investigated. Hierarchical Al alloy surfaces with microgrooves and nanograss structures were developed by a simple combination of one-directional mechanical sanding and post treatment in boiling de-ionized water (DIW). Three types of long-chain fluorocarbon oligomers of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PFDTS), 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane (PFDCS), and perfluorooctanoic acid (PFOA) were chemically vaporized onto these rough Al alloy surfaces. The PFDCS exhibited the lowest surface free energy of less than 10 mN/m. The contact angle and sliding angle measurements for water, ethylene glycol, and peanut oil verified the SAP property of hierarchical rough Al alloy surfaces treated with alkylsilane oligomers (PFDTS, PFDCS). However, the hierarchical surfaces treated with fluorocarbon oligomer with polar acidic tail (PFOA) showed highly amphiphobic properties but could not reach the threshold for SAP. Chemical stability of the hierarchical Al alloy surfaces treated with the fluorocarbon oligomers was tested under the harsh conditions of ultra-sonication in acetone and annealing at high temperature after different treatment times. Contact angle measurements revealed the robustness of the alkylsilane oligomers and deterioration of the PFOA coating particularly for low surface tension liquids. The robust adhesion and close-packing of the alkylsilane

  2. Plasma Electrolytic Oxidation (PEO) Coatings on an A356 Alloy for Improved Corrosion and Wear Resistance

    NASA Astrophysics Data System (ADS)

    Peng, Zhijing

    Plasma electrolytic oxidizing (PEO) is an advanced technique that has been used to deposit thick and hard ceramic coatings on aluminium (Al) alloys. This work was however to use the PEO process to produce thin ceramic oxide coatings on an A356 Al alloy for improving corrosion and wear resistance of the alloy. Effects of current density and treatment time on surface morphologies and thickness of the PEO coatings were investigated. The improvement of galvanic corrosion properties of the coated A356 alloy vs. steel and carbon fibre were evaluated in E85 fuel or NaCl environments. Tribological properties of the coatings were studied with comparison to the uncoated A356 substrate and other commercially-used engine bore materials. The research results indicated that the PEO coatings could have excellent tribological and corrosion properties for aluminium engine applications.

  3. Moisture resistant and anti-reflection optical coatings produced by plasma polymerization of organic compounds

    NASA Technical Reports Server (NTRS)

    Hollahan, J. R.; Wydeven, T.

    1975-01-01

    The need for protective coatings on critical optical surfaces, such as halide crystal windows or lenses used in spectroscopy, has long been recognized. It has been demonstrated that thin, one micron, organic coatings produced by polymerization of flourinated monomers in low temperature gas discharge (plasma) exhibit very high degrees of moisture resistence, e.g., hundreds of hours protection for cesium iodide vs. minutes before degradation sets in for untreated surfaces. The index of refraction of these coatings is intermediate between that of the halide substrate and air, a condition for anti-reflection, another desirable property of optical coatings. Thus, the organic coatings not only offer protection, but improved transmittance as well. The polymer coating is non-absorbing over the range 0.4 to 40 microns with an exception at 8.0 microns, the expected absorption for C-F bonds.

  4. Oxidation-resistant interfacial coatings for continuous fiber ceramic composites

    SciTech Connect

    Stinton, D.P.; Besmann, T.M.; Bleier, A.; Shanmugham, S.; Liaw, P.K.

    1995-08-01

    Continuous fiber ceramic composites mechanical behavior are influenced by the bonding characteristics between the fiber and the matrix. Finite modeling studies suggest that a low-modulus interfacial coating material will be effective in reducing the residual thermal stresses that are generated upon cooling from processing temperatures. Nicalon{trademark}/SiC composites with carbon, alumina and mullite interfacial coatings were fabricated with the SiC matrix deposited using a forced-flow, thermal gradient chemical vapor infiltration process. Composites with mullite interfacial coatings exhibited considerable fiber pull-out even after oxidation and have potential as a composite system.

  5. Effect of fluorocarbons on acetylcholinesterase activity and some counter measures

    NASA Technical Reports Server (NTRS)

    Young, W.; Parker, J. A.

    1975-01-01

    An isolated vagal sympathetic heart system has been successfully used for the study of the effect of fluorocarbons (FCs) on cardiac performance and in situ enzyme activity. Dichlorodifluoromethane sensitizes this preparation to sympathetic stimulation and to exogenous epinephrine challenge. Partial and complete A-V block and even cardiac arrest have been induced by epinephrine challenge in the FC sensitized heart. Potassium chloride alone restores the rhythmicity but not the normal contractility of the heart in such a situation. Addition of glucose will, however, completely restore the normal function of the heart which is sensitized by dichlorodifluoromethane. The ED 50 values of acetylcholinesterase activity which are used as a measure of relative effectiveness of fluorocarbons are compared with the maximum permissible concentration. Kinetic studies indicate that all the fluorocarbons tested so far are noncompetitive.

  6. Heat-resistant diffusion coating for niobium alloy

    SciTech Connect

    Zemskov, G.V.; Kogan, R.L.; Luk'yanov, V.M.

    1992-06-03

    The question of protecting niobium and its alloy from high-temperature corrosion is a current one at the present time. Diffusion coatings are receiving ever more widespread application for this purpose. Silicide diffusion coatings possess high durability. Much attention is being given abroad to a coating of chromium, titanium and silicon obtained by the method of vacuum treatment in an alloy of titanium with chromium, with subsequent siliconization. However, the indicated works do not present the results of the study for the purpose of selecting the optimal technological process ensuring a diffusion layer of maximal durability. The authors studied the possibility of using a simpler technological process as compared with that described for obtaining a tri-component coating containing titanium, chromium and silicon and protecting the niobium against oxidation at a temperature of 1100-1200 deg C.

  7. Oxidation resistance of composite silicide coatings on niobium

    SciTech Connect

    Gloshko, P.I.; Kurtsev, N.F.; Lisichenko, V.I.; Nadtoka, V.N.; Petrenko, M.I.; Zmii, V.I.

    1986-07-01

    This paper reports the oxidation of NbSi/sub 2/-MoSi/sub 2/ composite silicide coatings produced by diffusive siliconizing of molybdenum films on a niobium surface. Molybdenum-coated niobium was siliconized and an x-ray microspectral analysis of the composite silicide coating showed the phase composition to be an ca 80-um-thick outer molybdenum disilicide film with a characteristic coarsely crystalline columnar structure, and inner ca 20-um film of niobium disilicide consisting of the tiny columnar crystals, and a substrate/coating interface comprising a thin, 2-3 um film of lower silicide, i.e., Nb/sub 5/Si/sub 3/. The average grain sizes, unit cell parameters, and x-ray determined densities of the Mo films obtained by various methods are shown.

  8. Nanostructured wear resistant coating for reversible cultivator shovels: An experimental investigation

    NASA Astrophysics Data System (ADS)

    Dave, V.; Rao, G. P.; Tiwari, G. S.; Sanger, A.; Kumar, A.; Chandra, R.

    2016-04-01

    Cultivator, one of the agriculture farm tool, extensively suffers from the wear problem. In this paper, we report nanostructured chromium nitrite (CrN) coating for the cultivator shovels to mitigate wear problem. The (CrN) coating was developed using DC magnetron sputtering technique at 200 °C. The structural, morphological, hydrophobic and wear properties were investigated using X-ray diffractometer, scanning electron microscope, contact angle goniometer and custom designed soil bin assembly. The XRD reveals that the deposited coating was polycrystalline in nature with cubic structure. Also, The deposited coating was found to be anti wear resistant as well as hydrophobic in nature. The gravimetric wear for the coating developed at 200 °C coated was found out to be 8.15 gm and for non coated it was 14.48 gm tested for 100 hrs. The roughness of the coating plays an important role in determining the hydrophobicity of the coated film. Roughness and contact angle measured for 200 °C coated shovel was found out to be 11.17 nm and 105 ° respectively.

  9. Evaluation of Heat Checking and Washout of Heat Resistant Superalloys and Coatings for Die inserts

    SciTech Connect

    David Schwam; John F. Wallace; Yulong Zhu; Edward Courtright; Harold Adkins

    2005-01-30

    This project had two main objectives: (1) To design, fabricate and run a full size test for evaluating soldering and washout in die insert materials. This test utilizes the unique capabilities of the 350 Ton Squeeze Casting machine available in the Case Meal Casting Laboratory. Apply the test to evaluate resistance of die materials and coating, including heat resistant alloys to soldering and washout damage. (2) To evaluate materials and coatings, including heat resistant superalloys, for use as inserts in die casting of aluminum alloys.

  10. Polyglycerol coatings of glass vials for protein resistance.

    PubMed

    Höger, Kerstin; Becherer, Tobias; Qiang, Wei; Haag, Rainer; Friess, Wolfgang; Küchler, Sarah

    2013-11-01

    Proteins are surface active molecules which undergo non-specific adsorption when getting in contact with surfaces such as the primary packaging material. This process is critical as it may cause a loss of protein content or protein aggregation. To prevent unspecific adsorption, protein repellent coatings are of high interest. We describe the coating of industrial relevant borosilicate glass vials with linear methoxylated polyglycerol, hyperbranched polyglycerol, and hyperbranched methoxylated polyglycerol. All coatings provide excellent protein repellent effects. The hyperbranched, non-methoxylated coating performed best. The protein repellent properties were maintained also after applying industrial relevant sterilization methods (≥200 °C). Marginal differences in antibody stability between formulations stored in bare glass vials and coated vials were detected after 3 months storage; the protein repellent effect remained largely stable. Here, we describe a new material suitable for the coating of primary packaging material of proteins which significantly reduces the protein adsorption and thus could present an interesting new possibility for biomedical applications.

  11. Stress crack resistance of some pigmented and unpigmented tablet film coating systems.

    PubMed

    Okhamafe, A O; York, P

    1985-07-01

    Stress crack resistance parameters--tensile strength: Young's modulus ratio, relative surface energy, and toughness index--have been examined for unpigmented free films of hydroxypropyl methylcellulose containing polyvinyl alcohol, and polyethylene glycols 400 and 1000, as well as similar film systems pigmented with either talc or titanium dioxide. Incorporation of either polyvinyl alcohol or polyethylene glycols 400 and 1000 in hydroxypropyl methylcellulose film coatings eliminated the incidence of edge splitting in the coated tablets. Increase in pigment concentration generally led to a decrease in the crack resistance of pigmented films. There was a relation between the stress crack resistance of pigmented free films and the incidence of edge splitting of corresponding film coatings applied to aspirin tablets--generally, the higher the crack resistance the lower the incidence of edge splitting. A similar relationship applied to the unpigmented films only when the tensile strength: Young's modulus ratio was considered.

  12. Cause and Effects of Fluorocarbon Degradation in Electronics and Opto-Electronic Systems

    NASA Technical Reports Server (NTRS)

    Predmore, Roamer E.; Canham, John S.

    2002-01-01

    Trace degradation of fluorocarbon or halocarbon materials must be addressed in their application in sensitive systems. As the dimensions and/or tolerances of components in a system decrease, the sensitivity of the system to trace fluorocarbon or halocarbon degradation products increases. Trace quantities of highly reactive degradation products from fluorocarbons have caused a number of failures of flight hardware. It is of utmost importance that the risk of system failure, resulting from trace amounts of reactive fluorocarbon degradation products be addressed in designs containing fluorocarbon or halocarbon materials. Thermal, electrical, and mechanical energy input into the system can multiply the risk of failure.

  13. Novel fluoro-carbon functional monomer for dental bonding.

    PubMed

    Yoshihara, K; Yoshida, Y; Hayakawa, S; Nagaoka, N; Kamenoue, S; Okihara, T; Ogawa, T; Nakamura, M; Osaka, A; Van Meerbeek, B

    2014-02-01

    Among several functional monomers, 10-methacryloxydecyl dihydrogen phosphate (10-MDP) bonded most effectively to hydroxyapatite (HAp). However, more hydrolysis-resistant functional monomers are needed to improve bond durability. Here, we investigated the adhesive potential of the novel fluoro-carbon functional monomer 6-methacryloxy-2,2,3,3,4,4,5,5-octafluorohexyl dihydrogen phosphate (MF8P; Kuraray Noritake Dental Inc., Tokyo, Japan) by studying its molecular interaction with powder HAp using solid-state nuclear magnetic resonance ((1)H MAS NMR) and with dentin using x-ray diffraction (XRD) and by characterizing its interface ultrastructure at dentin using transmission electron microscopy (TEM). We further determined the dissolution rate of the MF8P_Ca salt, the hydrophobicity of MF8P, and the bond strength of an experimental MF8P-based adhesive to dentin. NMR confirmed chemical adsorption of MF8P onto HAp. XRD and TEM revealed MF8P_Ca salt formation and nano-layering at dentin. The MF8P_Ca salt was as stable as that of 10-MDP; MF8P was as hydrophobic as 10-MDP; a significantly higher bond strength was recorded for MF8P than for 10-MDP. In conclusion, MF8P chemically bonded to HAp. Despite its shorter size, MF8P possesses characteristics similar to those of 10-MDP, most likely to be associated with the strong chemical bond between fluorine and carbon. Since favorable bond strength to dentin was recorded, MF8P can be considered a good candidate functional monomer for bonding.

  14. Influence on the wear resistance of the particle size used in coatings of Alumina

    NASA Astrophysics Data System (ADS)

    Santos, A.; Guzmán, R.; Ramirez, Z. Y.

    2017-01-01

    In the literature, it is common to find that the size of the particles used in coatings through thermal spraying processes influences the hardness and wear resistance thereof; this project aimed to quantify the importance of this parameter in the adhesive and abrasive wear resistance when aluminium oxide is deposited on a substrate of AISI 1020 steel, through a thermal spraying by flame process. The methodology consisted of: a) morphological characterization of the powder used in the coatings by scanning electron microscopy, b) deposition of coatings, c) testing of adhesive and abrasive wear (ASTM G99-05 Standard test method for wear testing with a pin-on-disk apparatus and ASTM G65–04 Standard test method for measuring abrasion using dry sand/rubber wheel apparatus), and d) statistical analysis to determine the influence of particle size on wear resistance. The average size of the powder used for coatings was 92, 1690, 8990 and 76790nm. The obtained results allow to identify an inversely proportional behaviour between particle size and wear resistance, in both types of wear (adhesive and abrasive) is shown a logarithmic trend indicating an increase in loss mass during the test as the particle size is also increased and therefore a decrease in wear resistance of the coating.

  15. Oxidation resistant coatings for CoSb3

    NASA Astrophysics Data System (ADS)

    Zawadzka, K.; Godlewska, E.; Mars, K.; Nocun, M.

    2012-06-01

    Doped cobalt antimonides, are used as components of thermoelectric devices at temperatures not exceeding 450 °C because of poor thermal and chemical stability. In absence of oxygen they degrade by sublimation of antimony, while in air they easily oxidize to form volatile antimony oxides and non-volatile thick double oxide scales [1]. In both cases, protective coatings are indispensable to ensure safe performance of thermoelectric devices over extended times. The most promising solution, reported so far, is a thick aerogel coating, which practically stops antimony loss by sublimation. The assessment of coating effectiveness is generally based on thermogravimetric tests in vacuum, so permeability of oxygen and protection from oxidation cannot be evaluated. The paper presents investigations on the development of protective coatings, which would prevent oxidation of CoSb3. Two types of coatings were applied: magnetron sputtered Cr-Si thin layers [2] and thick enamel layers. Testing involved interrupted oxidation in air for 20-80 h at 500 °C and 600 °C. The Cr-Si thin layers appeared oxygen-tight at 500 °C while the enamel layers - even at 600 °C.

  16. NANOSCALE BOEHMITE FILLER FOR CORROSION AND WEAR RESISTANT POLYPHENYLENESULFIDE COATINGS.

    SciTech Connect

    SUGAMA,T.

    2003-06-26

    The authors evaluated the usefulness of nanoscale boehmite crystals as a filler for anti-wear and anti-corrosion polyphenylenesulfide (PPS) coatings exposed to a very harsh, 300 C corrosive geothermal environment. The boehmite fillers dispersed uniformly into the PPS coating, conferring two advanced properties: First, they reduced markedly the rate of blasting wear; second, they increased the PPS's glass transition temperature and thermal decomposition temperature. The wear rate of PPS surfaces was reduced three times when 5wt% boehmite was incorporated into the PPS. During exposure for 15 days at 300 C, the PPS underwent hydrothermal oxidation, leading to the substitution of sulfide linkages by the sulfite linkages. However, such molecular alteration did not significantly diminish the ability of the coating to protect carbon steel against corrosion. In fact, PPS coating filled with boehmite of {le} 5wt% adequately mitigated its corrosion in brine at 300 C. One concern in using this filler was that it absorbs brine. Thus, adding an excess amount of boehmite was detrimental to achieving the maximum protection afforded by the coatings.

  17. Gastro-resistant characteristics of GRAS-grade enteric coatings for pharmaceutical and nutraceutical products.

    PubMed

    Czarnocka, Justyna K; Alhnan, Mohamed A

    2015-01-01

    The use of naturally derived excipients to develop enteric coatings offers significant advantages over conventional synthetic polymers. Unlike synthetic polymers, they are biodegradable, relatively abundant, have no daily intake limits or restrictions on use for dietary and nutraceutical products. However, little information is available on their dissolution properties under different gastrointestinal conditions and in comparison to each other. This work investigated the gastric resistance properties of commercially available GRAS-based coating technologies. Three coating systems were evaluated: ethyl cellulose+carboxymethyl cellulose (EC-CMC), ethyl cellulose+sodium alginate (EC-Alg) and shellac+sodium alginate (Sh-Alg) combinations. The minimum coating levels were optimized to meet USP pharmacopoeial criteria for delayed release formulations (<10% release after 2h in pH 1.2 followed by >80% release after 45 min of pH change). Theophylline 150 mg tablets were coated with 6.5%, 7%, and 2.75% coating levels of formulations EC-CMC, EC-Alg and Sh-Alg, respectively. In vitro dissolution test revealed a fast release in pH 6.8 for ethyl cellulose based coatings: t80% value of 65 and 45 min for EC-CMC and EC-Alg respectively, while a prolonged drug release from Sh-Alg coating was observed in both pH 6.8 and 7.4 phosphate buffers. However, when more biologically relevant bicarbonate buffer was used, all coatings showed slower drug release. Disintegration test, carried out in both simulated gastric and intestinal fluid, confirmed good mechanical resistance of EC-CMC and EC-Alg coating, and revealed poor durability of the thinner Sh-Alg. Under elevated gastric pH conditions (pH 2, 3 and 4), EC-CMC and EC-Alg coatings were broken after 70, 30, 55 min and after 30, 15, 15 min, respectively, while Sh-Alg coated tablets demonstrated gastric resistance at all pH values. In conclusion, none of the GRAS-grade coatings fully complied with the different biological demands of delayed

  18. Novel Application of ZSM-5 Zeolite: Corrosion-Resistant Coating in Chemical Process Industry

    NASA Astrophysics Data System (ADS)

    Pande, H. B.; Parikh, P. A.

    2013-01-01

    As-synthesized zeolite ZSM-5 containing the structure-directing agent, tetrapropyl ammonium bromide, when used as a coating material on mild steel substrate material, has been found to offer a promising corrosion resisting results against HCl, HNO3, H3PO4, and H2SO4 of various concentrations at temperatures up to 60 °C under stagnant and stirred conditions. Stable and continuous coated layer is observed under the conditions studied in this work by weight loss and electrochemical methods. Encouraging results in terms of corrosion inhibition efficiency indicate high potential with zeolite (Si/Al ratio 25) material. Material costs compare favorably for zeolite coating against the conventionally used materials. Summarily, zeolite offers an environment-friendly and cost-effective alternate to the other toxic and carcinogenic materials as corrosion-resistant coating.

  19. Electro-spark deposition: A technique for producing wear resistant coatings

    SciTech Connect

    Sheldon, G.L. ); Johnson, R.N. )

    1984-12-01

    Electro-spark deposition (ESD) is a coating process using short duration, high current electrical pulses to deposit an electrode material on a metallic substrate. A principal attribute of the process is its ability to apply metallurgically bonded coatings with such a low total heat input that the bulk substrate material remains at or near ambient temperatures. A review of the process is briefly given, then current research using WC-TiC and Cr{sub 3}C{sub 2} electrodes to deposit coatings on Type 316 stainless steel and other substrates is presented. The ESD carbide coatings were found to be exceptionally hard, wear-resistant and spalling-resistant in high-stress rubbing tests. Several applications for nuclear reactor components are described. 17 refs., 18 figs., 1 tab.

  20. Development of multilayer oxidation resistant coatings on Cr-50Nb alloy

    NASA Astrophysics Data System (ADS)

    Zheng, Haizhong; Xiong, Lingling; Luo, Qinhao; Lu, Shiqiang

    2015-12-01

    To protect Cr-50Nb alloys from high-temperature oxidation, the Al2O3/Si-Al multilayer coatings were produced by pack cementation process, followed by sol-gel process and hot pressing. The results indicate that the multilayer coating is dense and exhibits good adherence to the substrate, which consists of a compact Al2O3 outer layer and an inner layer composed of Si, Al, Cr, Nb. Uncoated Cr-50Nb alloy occurs catastrophic oxidation at the initial oxidation stage at 1200 °C. However, the scale spalling resistance of the multilayer coating is improved significantly, and the multilayer coating exhibits good resistance to oxidation. During cyclic oxidation in air at 1200 °C for 100 h, the weight loss is 0.13 mg/cm2 and the mass gain is 3.38 mg/cm2.

  1. High temperature oxidation resistant coatings for the directionally solidified Ni-Nb-Cr-Al eutectic superalloy

    NASA Technical Reports Server (NTRS)

    Strangman, T. E.; Ulion, N. E.; Felten, E. J.

    1977-01-01

    Protective coatings required for the Ni-Nb-Cr-Al directionally solidified eutectic superalloy were developed and evaluated on the basis of oxidation resistance, diffusional stability, thermal fatigue, and creep resistance. NiCrAlY+Pt and NiCrAlY physical vapor-deposition coating systems exhibited the best combination of properties. Burner-rig testing indicated that the useful life of a 127-micron-thick NiCrAlY+Pt coating exceeds 1000 h at 1366 K. Eutectic-alloy creep lives at 1311 K and a stress of 151.7 MN/sq m were greater for NiCrAlY+Pt-coated specimens than for uncoated specimens by a factor of two.

  2. Method For Improving The Oxidation Resistance Of Metal Substrates Coated With Thermal Barrier Coatings

    DOEpatents

    Thompson, Anthony Mark; Gray, Dennis Michael; Jackson, Melvin Robert

    2003-05-13

    A method for providing a protective coating on a metal-based substrate is disclosed. The method involves the application of an aluminum-rich mixture to the substrate to form a discontinuous layer of aluminum-rich particles, followed by the application of a second coating over the discontinuous layer of aluminum-rich particles. Aluminum diffuses from the aluminum-rich layer into the substrate, and into any bond coat layer which is subsequently applied. Related articles are also described. A method for providing a protective coating on a metal-based substrate is disclosed. The method involves the application of an aluminum-rich mixture to the substrate to form a discontinuous layer of aluminum-rich particles, followed by the application of a second coating over the discontinuous layer of aluminum-rich particles. Aluminum diffuses from the aluminum-rich layer into the substrate, and into any bond coat layer which is subsequently applied. Related articles are also described.

  3. The corrosion resistance of zinc coatings in the presence of boron-doped detonation nanodiamonds (DND)

    NASA Astrophysics Data System (ADS)

    Burkat, G. K.; Alexandrova, G. S.; Dolmatov, V. Yu; Osmanova, E. D.; Myllymäki, V.; Vehanen, A.

    2017-02-01

    The effect of detonation nanodiamonds, doped with boron (boron-DND) in detonation synthesis on the process of zinc electrochemical deposition from zincate electrolyte is investigated. It is shown that the scattering power (coating uniformity) increases 2-4 times (depending on the concentration of DND-boron electrolyte conductivity does not change, the corrosion resistance of Zn- DND -boron coating increases 2.6 times in 3% NaCl solution (corrosion currents) and 3 times in the climatic chamber.

  4. Stability and Normal Zone Propagation Speed in YBCO Coated Conductors with Increased Interfacial Resistance (PREPRINT)

    DTIC Science & Technology

    2010-03-01

    AFRL-RZ-WP-TP-2010-2085 STABILITY AND NORMAL ZONE PROPAGATION SPEED IN YBCO COATED CONDUCTORS WITH INCREASED INTERFACIAL RESISTANCE...August 2006 – 25 August 2008 4. TITLE AND SUBTITLE STABILITY AND NORMAL ZONE PROPAGATION SPEED IN YBCO COATED CONDUCTORS WITH INCREASED INTERFACIAL...reproduce, release, perform, display, or disclose the work. 14. ABSTRACT We will discuss how stability and speed of normal zone propagation in YBCO

  5. The Corrosion Resistance and Paint Adhesion Properties of Chromate Conversion Coatings on Aluminium and Its Alloys

    DTIC Science & Technology

    1976-05-01

    aluminium and its alloys has been evaluated with respect to both corrosion resistance of, and paint adhesion to, the chromate films. The process involves...The findings in this Report will be used as the basis for a Defence Standard for chromate conversion coatings for aluminium and aluminium alloys...3 PROPRIETARY CHROMATE CONVERSION COATINGS FOR ALUMINIUM 17 4 PAINT ADHESION 19 5 DISCUSSION 21 6 CONCLUSIONS 24 Acknowledgments 25 Appendix A

  6. Heat sealable, flame and abrasion resistant coated fabric. [clothing and containers for space exploration

    NASA Technical Reports Server (NTRS)

    Tschirch, R. P.; Sidman, K. R. (Inventor)

    1981-01-01

    Flame retardant, abrasion resistant elastomeric compositions are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Coated fabrics employing such elastomeric compositions as coating film are flexible, lightweight, and air impermeable and can be made using heat or dielectric sealing procedures.

  7. A durability test rig and methodology for erosion-resistant blade coatings in turbomachinery

    NASA Astrophysics Data System (ADS)

    Leithead, Sean Gregory

    A durability test rig for erosion-resistant gas turbine engine compressor blade coatings was designed, completed and commissioned. Bare and coated 17-4PH steel V103-profile blades were rotated at up to 11500 rpm and impacted with Garnet sand for 5 hours at an average concentration of 2.51 gm3of air , at a blade leading edge Mach number of 0.50. The rig was determined to be an acceptable first stage axial compressor representation. Two types of 16 microm-thick coatings were tested: Titanium Nitride (TiN) and Chromium-Aluminum-Titanium Nitride (CrAlTiN), both applied using an Arc Physical Vapour Deposition technique at the National Research Council in Ottawa, Canada. A Leithead-Allan-Zhao (LAZ) score was created to compare the durability performance of uncoated and coated blades based on mass-loss and blade dimension changes. The bare blades' LAZ score was set as a benchmark of 1.00. The TiN-coated and CrAlTiN-coated blades obtained LAZ scores of 0.69 and 0.41, respectively. A lower score meant a more erosion-resistant coating. Major modes of blade wear included: trailing edge, leading edge and the rear suction surface. Trailing edge thickness was reduced, the leading edge became blunt, and the rear suction surface was scrubbed by overtip and recirculation zone vortices. It was found that the erosion effects of vortex flow were significant. Erosion damage due to reflected particles was not present due to the low blade solidity of 0.7. The rig is best suited for studying the performance of erosion-resistant coatings after they are proven effective in ASTM standardized testing. Keywords: erosion, compressor, coatings, turbomachinery, erosion rate, blade, experimental, gas turbine engine

  8. Development of coatings with improved corrosion resistance in sulfur-containing environments

    SciTech Connect

    Natesan, K. ); Johnson, R.N. )

    1990-01-01

    Corrosion of metallic structure materials at elevated temperatures in complex multicomponent gas environments is a potential problem in many fossil energy systems, especially those using coal as a feedstock. The use of appropriate corrosion-resistant coatings on metallic components can minimize material degradation and extend component life. In the present study, the chemical compatibility of a number of coatings is examined by exposing them to simulated oxygen/sulfur mixed-gas environments at metal temperatures of 500 and 650{degree}C. Coatings were developed via pack cementation and electrospark deposition techniques on T22 and T91 substrates. The oxidation/sulfidation test results for the coated specimens were compared with those for the uncoated alloys and for high-chromium structural alloys of interest in fossil energy applications. Coatings tested were Fe--Cr--Mo. Alloys tested include nickel base, nickel, and chromium alloys, and stainless steel 310. 5 refs., 12 figs., 2 tabs.

  9. Electrically Conductive, Corrosion-Resistant Coatings Through Defect Chemistry for Metallic Interconnects

    SciTech Connect

    Anil V. Virkar

    2006-12-31

    The principal objective of this work was to develop oxidation protective coatings for metallic interconnect based on a defect chemistry approach. It was reasoned that the effectiveness of a coating is dictated by oxygen permeation kinetics; the slower the permeation kinetics, the better the protection. All protective coating materials investigated to date are either perovskites or spinels containing metals exhibiting multiple valence states (Co, Fe, Mn, Cr, etc.). As a result, all of these oxides exhibit a reasonable level of electronic conductivity; typically at least about {approx}0.05 S/cm at 800 C. For a 5 micron coating, this equates to a maximum {approx}0.025 {Omega}cm{sup 2} area specific resistance due to the coating. This suggests that the coating should be based on oxygen ion conductivity (the lower the better) and not on electronic conductivity. Measurements of ionic conductivity of prospective coating materials were conducted using Hebb-Wagner method. It was demonstrated that special precautions need to be taken to measure oxygen ion conductivity in these materials with very low oxygen vacancy concentration. A model for oxidation under a protective coating is presented. Defect chemistry based approach was developed such that by suitably doping, oxygen vacancy concentration was suppressed, thus suppressing oxygen ion transport and increasing effectiveness of the coating. For the cathode side, the best coating material identified was LaMnO{sub 3} with Ti dopant on the Mn site (LTM). It was observed that LTM is more than 20 times as effective as Mn-containing spinels. On the anode side, LaCrO3 doped with Nb on the Cr site (LNC) was the material identified. Extensive oxidation kinetics studies were conducted on metallic alloy foils with coating {approx}1 micron in thickness. From these studies, it was projected that a 5 micron coating would be sufficient to ensure 40,000 h life.

  10. Gain and loss mechanisms in fluorocarbon plasmas

    NASA Astrophysics Data System (ADS)

    Nelson, Caleb Timothy

    Understanding dominant reaction channels for important gas-phase species in fluorocarbon plasmas is crucial to the ability to control surface evolution and morphology. In order to accomplish this goal a modified GEC reference ICP reactor is used in tandem with Fourier transform infrared spectroscopy (FTIR) to measure the densities of stable species. Integrated absorption cross-sections are presented for all fundamental bands in the 650 cm-1 to 2000 cm-1 region for C3F6, C4F 8, C3F8, C2F6, C2F 4, and CF4. The results show that although the absorption profile changes significantly, the integrated absorption cross-sections, with the exception of CF4, do not change significantly as gas temperature increases from 25°C to 200°C. However, the internal temperature of the absorbing species can be estimated from the rotational band maximum in most cases. Species densities obtained with the aforementioned cross-sections are used with a novel analysis technique to quantify gain and loss rates as functions of residence time, pressure, and deposited power. CF4, C2F6, C3F8, and C4F 10, share related production channels, which increase in magnitude as the plasma pressure, deposited power, or surface temperature are raised. CF 2 is primarily produced through a combination of surface production (the magnitude also increases with temperature) and electron impact dissociation of C2F4, while it is predominantly lost in the large reactor to gas-phase addition to form C2F4. Time-resolved FTIR results are used to measure a cross-section of 1.8x10-14 cm3/s for the reaction between CF2 radicals creating C2F4. Finally, C2F4 originates through the electron impact dissociation of c- C4F8. The loss process for C2F4 is undetermined, but the results indicate that it could occur on reactor surfaces. Neither the density of fluorine nor the ion flux to the chuck surface changes substantially with wall temperature. We show that increases in the deposition rate in a heated chamber are due to an

  11. Development of a Long-Life-Cycle, Highly Water-Resistant Solar Reflective Retrofit Roof Coating

    SciTech Connect

    Polyzos, Georgios; Hunter, Scott; Sharma, Jaswinder; Cheng, Mengdawn; Chen, Sharon S.; Demarest, Victoria; Fabiny, William; Destaillats, Hugo; Levinson, Ronnen

    2016-03-04

    Highly water-resistant and solar-reflective coatings for low-slope roofs are potentially among the most economical retrofit approaches to thermal management of the building envelope. Therefore, they represent a key building technology research program within the Department of Energy. Research efforts in industry and the Department of Energy are currently under way to increase long-term solar reflectance on a number of fronts. These include new polymer coatings technologies to provide longer-lasting solar reflectivity and improved test methodologies to predict long-term soiling and microbial performance. The focus on long-term improvements in soiling and microbial resistance for maximum reflectance does not address the single most important factor impacting the long-term sustainability of low-slope roof coatings: excellent water resistance. The hydrophobic character of asphaltic roof products makes them uniquely suitable for water resistance, but their low albedo and poor exterior durability are disadvantages. A reflective coating that maintains very high water resistance with increased long-term resistance to soiling and microbial activity would provide additional energy savings and extend roof service life.

  12. 21 CFR 177.1380 - Fluorocarbon resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., Extrusion, and Coating Materials,” which is incorporated by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from the American Society for Testing and Materials, 1916...

  13. 21 CFR 177.1380 - Fluorocarbon resins.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., Extrusion, and Coating Materials,” which is incorporated by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from the American Society for Testing and Materials, 1916...

  14. 21 CFR 177.1380 - Fluorocarbon resins.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., Extrusion, and Coating Materials,” which is incorporated by reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from the American Society for Testing and Materials, 1916...

  15. 21 CFR 177.1380 - Fluorocarbon resins.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Method D 3275-89 “Standard Specification for E-CTFE-Fluoroplastic Molding, Extrusion, and Coating... may be obtained from the American Society for Testing and Materials, 1916 Race St., Philadelphia,...

  16. METHOD FOR DETERMINING THE STABILITY OF FLUOROCARBON IOLS

    DOEpatents

    Sheldon, Z.D.; Haendler, H.M.

    1959-07-21

    A method of determining the stability of a fluorocarbon oil to uranium hexafluoride is presented. The method comprises reacting a weighed sample of the oil with condensed uranium hexafluoride in a reaction zone and titrating the amount of uranium tetrafluoride produced with potassium dichromate.

  17. Method and means for producing fluorocarbon finishes on fibrous structures

    NASA Technical Reports Server (NTRS)

    Toy, Madeline S. (Inventor); Stringham, Roger S. (Inventor); Fogg, Lawrence C. (Inventor)

    1981-01-01

    An improved process and apparatus is provided for imparting chemically bonded fluorocarbon finishes to textiles. In the process, the textiles are contacted with a gaseous mixture of fluoroolefins in an inert diluent gas in the presence of ultraviolet light under predetermined conditions.

  18. Biocorrosion resistance of coated magnesium alloy by microarc oxidation in electrolyte containing zirconium and calcium salts

    NASA Astrophysics Data System (ADS)

    Wang, Ya-Ming; Guo, Jun-Wei; Wu, Yun-Feng; Liu, Yan; Cao, Jian-Yun; Zhou, Yu; Jia, De-Chang

    2014-09-01

    The key to use magnesium alloys as suitable biodegradable implants is how to adjust their degradation rates. We report a strategy to prepare biocompatible ceramic coating with improved biocorrosion resistance property on AZ91D alloy by microarc oxidation (MAO) in a silicate-K2ZrF6 solution with and without Ca(H2PO4)2 additives. The microstructure and biocorrosion of coatings were characterized by XRD and SEM, as well as electrochemical and immersion tests in simulated body fluid (SBF). The results show that the coatings are mainly composed of MgO, Mg2SiO4, m-ZrO2 phases, further Ca containing compounds involve the coating by Ca(H2PO4)2 addition in the silicate-K2ZrF6 solution. The corrosion resistance of coated AZ91D alloy is significantly improved compared with the bare one. After immersing in SBF for 28 d, the Si-Zr5-Ca0 coating indicates a best corrosion resistance performance.

  19. Radiation-Resistant Hybrid Lotus Effect for Achieving Photoelectrocatalytic Self-Cleaning Anticontamination Coatings

    NASA Technical Reports Server (NTRS)

    Taylor, Edward W.; Pirich, Ronald G.

    2011-01-01

    An experiment involving radiation-resistant hydrophobic coatings is planned for space exposure and experimental testing on the International Space Station (ISS) in 2011. The Lotus biocide coatings are designed for supporting space exploration missions. This innovation is an antibacterial, anti-contamination, and self-cleaning coating that uses nano-sized semiconductor semimetal oxides to neutralize biological pathogens and toxic chemicals, as well as to mitigate dust accumulation (see figure). The Lotus biocide coating is thin (approximately microns thick), lightweight, and the biocide properties will not degrade with time or exposure to biological or chemical agents. The biocide is stimulated chemically (stoichiometric reaction) through exposure to light (photocatalysis), or by an applied electric field (electrocatalysis). The hydrophobic coating samples underwent preliminary high-energy proton and alpha-ray (helium ion) irradiations at the Lawrence Berkeley National Laboratory 88" cyclotron and demonstrated excellent radiation resistance for a portion of the Galactic Cosmic Ray (GRC) and Solar Proton spectrum. The samples will undergo additional post-flight studies when returned to Earth to affirm further the radiation resistance properties of the space exposed coatings.

  20. Amorphous metal formulations and structured coatings for corrosion and wear resistance

    DOEpatents

    Farmer, Joseph C [Tracy, CA

    2011-12-13

    A system for coating a surface comprising providing a source of amorphous metal that contains more than 11 elements and applying the amorphous metal that contains more than 11 elements to the surface by a spray. Also a coating comprising a composite material made of amorphous metal that contains more than 11 elements. An apparatus for producing a corrosion-resistant amorphous-metal coating on a structure comprises a deposition chamber, a deposition source in the deposition chamber that produces a deposition spray, the deposition source containing a composite material made of amorphous metal that contains more than 11 elements, and a system that directs the deposition spray onto the structure.

  1. Amorphous metal formulations and structured coatings for corrosion and wear resistance

    DOEpatents

    Farmer, Joseph C.

    2014-07-15

    A system for coating a surface comprising providing a source of amorphous metal that contains more than 11 elements and applying the amorphous metal that contains more than 11 elements to the surface by a spray. Also a coating comprising a composite material made of amorphous metal that contains more than 11 elements. An apparatus for producing a corrosion-resistant amorphous-metal coating on a structure comprises a deposition chamber, a deposition source in the deposition chamber that produces a deposition spray, the deposition source containing a composite material made of amorphous metal that contains more than 11 elements, and a system that directs the deposition spray onto the structure.

  2. Electrodeposition of high corrosion resistance Cu/Ni-P coating on AZ91D magnesium alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Shan; Cao, Fahe; Chang, Linrong; Zheng, JunJun; Zhang, Zhao; Zhang, Jianqing; Cao, Chunan

    2011-08-01

    High corrosion resistance Cu/Ni-P coatings were electrodeposited on AZ91D magnesium alloy via suitable pretreatments, such as one-step acid pickling-activation, once zinc immersion and environment-friendly electroplated copper as the protective under-layer, which made Ni-P deposit on AZ91D Mg alloy in acid plating baths successfully. The pH value and current density for Ni-P electrodeposition were optimized to obtain high corrosion resistance. With increasing the phosphorous content of the Ni-P coatings, the deposits were found to gradually transform to amorphous structure and the corrosion resistance increased synchronously. The anticorrosion ability of AZ91D Mg alloy was greatly improved by the amorphous Ni-P deposits, which was investigated by potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS). The corrosion current density ( Icorr) of the coated Mg alloy substrate is about two orders of magnitude less than that of the uncoated.

  3. Study of coatings for improved fire and decay resistance of mine timbers

    NASA Technical Reports Server (NTRS)

    Baum, B.

    1977-01-01

    The purpose of this program was to find a fire- and rot-retardant polymer/fungicide reaction product for coating mine timbers. Fire-retardant polymers were screened as films and coatings on fir wood. Curable polyimide appeared to be flame retardant and evolved a minimum of fumes when exposed to a flame. Several organic and metal, low toxicity, fungicides were reacted with the polyimide in-situ on the wood. These coated samples were screened for fungus resistance. All formulations rated well - even the polyimide film without additives was fungicidal. The fir wood control itself resisted internal damage during the ten weeks of fungus exposure. A more severe test for fungus resistance will be required.

  4. Fatigue resistant carbon coatings for rolling/sliding contacts

    SciTech Connect

    Singh, Harpal; Ramirez, Giovanni; Eryilmaz, Osman; Greco, Aaron; Doll, Gary; Erdemir, Ali

    2016-06-01

    The growing demands for renewable energy production have recently resulted in a significant increase in wind plant installation. Field data from these plants show that wind turbines suffer from costly repair, maintenance and high failure rates. Often times the reliability issues are linked with tribological components used in wind turbine drivetrains. The primary failure modes in bearings and gears are associated with micropitting, wear, brinelling, scuffing, smearing and macropitting all of which occur at or near the surface. Accordingly, a variety of surface engineering approaches are currently being considered to alter the near surface properties of such bearings and gears to prevent these tribological failures. In the present work, we have evaluated the tribological performance of compliant highly hydrogenated diamond like carbon coating developed at Argonne National Laboratory, under mixed rolling/sliding contact conditions for wind turbine drivetrain components. The coating was deposited on AISI 52100 steel specimens using a magnetron sputter deposition system. The experiments were performed on a PCS Micro-Pitting-Rig (MPR) with four material pairs at 1.79 GPa contact stress, 40% slide to roll ratio and in polyalphaolefin (PAO4) basestock oil (to ensure extreme boundary conditions). The post-test analysis was performed using optical microscopy, surface profilometry, and Raman spectroscopy. The results obtained show a potential for these coatings in sliding/rolling contact applications as no failures were observed with coated specimens even after 100 million cycles compared to uncoated pair in which they failed after 32 million cycles, under the given test conditions.

  5. Antisoiling technology: Theories of surface soiling and performance of antisoiling surface coatings

    NASA Technical Reports Server (NTRS)

    Cuddihy, E. F.; Willis, P. B.

    1984-01-01

    Physical examination of surfaces undergoing natural outdoor soiling suggests that soil matter accumulates in up to three distinct layers. The first layer involves strong chemical attachment or strong chemisorption of soil matter on the primary surface. The second layer is physical, consisting of a highly organized arrangement of soil creating a gradation in surface energy from a high associated with the energetic first layer to the lowest possible state on the outer surfce of the second layer. The lowest possible energy state is dictated by the physical nature of the regional atmospheric soiling materials. These first two layers are resistant to removal by rain. The third layer constitutes a settling of loose soil matter, accumulating in dry periods and being removed during rainy periods. Theories and evidence suggest that surfaces that should be naturally resistant to the formation of the first two-resistant layers should be hard, smooth, hydrophobic, free of first-period elements, and have the lowest possible surface energy. These characteristics, evolving as requirements for low-soiling surfaces, suggest that surfaces or surface coatings should be of fluorocarbon chemistry. Evidence for the three-soil-layer concept, and data on the positive performance of candidate fluorocarbon coatings on glass and transparent plastic films after 28 months of outdoor exposure, are presented.

  6. Extended Functionality of Environmentally-Resistant Mo-Si-B-Based Coatings

    NASA Astrophysics Data System (ADS)

    Perepezko, J. H.; Sakidja, R.

    2013-02-01

    Multiphase Mo-Si-B alloys with compositions which yield the ternary intermetallic Mo5SiB2 (T2) phase as a key microstructure constituent together with the Mo and Mo3Si phases, offer an attractive balance of high melting temperature, oxidation resistance, and mechanical properties. The investigation of reaction kinetics involving the T2 phase enables the analysis of oxidation in terms of diffusion pathways and the design of effective coatings. From this basis, kinetic biasing is used together with pack cementation to develop Mo-Si-B-based multilayered coatings with an aluminoborosilica surface and in situ diffusion barriers with self-healing characteristics for enhanced oxidation resistance. While a combustion environment contains water vapor that can accelerate an attack of silica-based coatings, the Mo-Si-B-based coatings provide oxidation resistance in water vapor up to at least 1,500°C. An exposure to hot ionized gas species generated in an arc jet confirms the robust coating performance in extreme environments. To extend the application beyond Mo-based systems, a two-stage process has been implemented to provide effective oxidation resistance for refractory metal cermets, SiC and ZrB2 ultra-high-temperature composites.

  7. Effect of fluorocarbon-for-blood exchange on regional blood flow in rats

    SciTech Connect

    Lee, P.A.; Sylvia, A.L.; Piantadosi, C.A. )

    1988-04-01

    Cerebrocirculatory responses to total perfluorocarbon (FC-43)-for-blood replacement were studied in anesthetized, ventilated rats breathing 100% O{sub 2}. Changes in total and regional cerebral blood flow (CBF) were measured using the radiolabeled-microsphere technique. The data were compared with two control groups of hemoglobin-circulated animals; one group was exposed to arterial hypoxia and the other to isovolemic hemodilution with Krebs-Henseleit-albumin (KHA) solution. Exchange transfusion with FC-43 doubled total and regional CBF, causing preferential flow increases to the cortex and cerebellum. Estimated cerebrovascular resistance fell to 50% of the preexchange value. Both hemodilution and hypoxia control experiments produced CBF responses similar to those obtained in FC-43 animals. Although calculated arterial O{sub 2} contents in all three groups of animals were similar, blood viscosity was normal in hypoxic rats and reduced in KHA and FC-43 animals. Since arterial and cerebrovenous Po{sub 2}s were both high in fluorocarbon-circulated rats, over results suggest that decreased O{sub 2} content and perhaps lower viscosity of the circulating fluorocarbon were responsible for increases in CBF required to maintain sufficient delivery of O{sub 2} to the brain.

  8. Development of a special purpose spacecraft interior coating, phase 1

    NASA Technical Reports Server (NTRS)

    Bartoszek, E. J.; Nannelli, P.

    1975-01-01

    Coating formulations were developed consisting of latex blends of fluorocarbon polymers, acrylic resins, stabilizers, modifiers, other additives, and a variety of inorganic pigments. Suitable latex primers were also developed from an acrylic latex base. The formulations dried to touch in about one hour and were fully dry in about twenty-four hours under normal room temperature and humidity conditions. The resulting coatings displayed good optical and mechanical properties, including excellent bonding to (pre-treated) substrates. In addition, the preferred compositions were found to be self-extinguishing when applied to nonflammable substrates and could meet the offgassing requirements specified by NASA for the intended application. Improvements are needed in abrasion resistance and hardness.

  9. Investigation of thermostability of resistive coatings based on carbon-filled polyurethane

    NASA Astrophysics Data System (ADS)

    Potekaev, A. I.; Malinovskaya, T. D.; Melentyev, S. V.; Pavlov, S. V.

    2015-10-01

    The influence of thermal treatment and dispersed carbon fillers on the thermostability of polyurethane binder is established. The conditions of thermal treatment of thick film composite resistive coatings have been defined to be further used in structures of electric heaters. It was found that the thermostability of resistive coatings based on polyurethane varnish Kontracid D3010 is reached by means of thermal treatment at a temperature of 120°C during 2 hours and is characterized by the completion of a reaction between the hydroxyl and isocyanate groups.

  10. Corrosion Resistance of 304L SS Spray Coated with Zirconia Nanoparticles

    NASA Astrophysics Data System (ADS)

    Maheswari, A. Uma; Sivakumar, M.; Indhumathi, N.; Mohan, Sreedevi R.

    2016-09-01

    Influence of substrate temperature on corrosion (in 3.5% NaCl) and wear resistance of nanostructured zirconia thin film coated 304L SS substrates are studied by electrochemical and nano-indentation methods. This analysis shows 304L SS substrate spray coated with nanostructured zirconia at substrate temperature closer to the boiling point of the spray solvent ethanol exhibited good corrosion and wear resistance behaviour. This is because of the compressive stress developed during film fabrication at lower substrate temperature (∼50 °C) and hence constrains the indentation plasticity, which leads to higher indentation load than the bare 304L SS.

  11. Dwindling the resistance value of PEDOT:PSS - coated on fabric yarns

    NASA Astrophysics Data System (ADS)

    Amba Sankar K., N.; Mohanta, Kallol

    2016-05-01

    Herein we describe by dip coating method to transform typical fabric yarn to conductive fiber. Different types of yarns have been used to coat from a known conductive polymer, Poly (3,4ethylenedioxythiophene) Poly (styrene sulfonic acid). We have optimized the method to have lesser resistance of the conductive yarns. The minimum resistance achieved has a value of 77 Ω/cm. This value is not high as metals but could be comparable to that of metal oxides or semiconducting materials. However, flexibility of yarns and feeling of fabric combining with the conductivity developed in this process is suitable for wearable electronics and also as gas sensors, electromagnetic shielding.

  12. 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.

  13. Enhancement of oxidation resistance via a self-healing boron carbide coating on diamond particles

    PubMed Central

    Sun, Youhong; Meng, Qingnan; Qian, Ming; Liu, Baochang; Gao, Ke; Ma, Yinlong; Wen, Mao; Zheng, Weitao

    2016-01-01

    A boron carbide coating was applied to diamond particles by heating the particles in a powder mixture consisting of H3BO3, B and Mg. The composition, bond state and coverage fraction of the boron carbide coating on the diamond particles were investigated. The boron carbide coating prefers to grow on the diamond (100) surface than on the diamond (111) surface. A stoichiometric B4C coating completely covered the diamond particle after maintaining the raw mixture at 1200 °C for 2 h. The contribution of the boron carbide coating to the oxidation resistance enhancement of the diamond particles was investigated. During annealing of the coated diamond in air, the priory formed B2O3, which exhibits a self-healing property, as an oxygen barrier layer, which protected the diamond from oxidation. The formation temperature of B2O3 is dependent on the amorphous boron carbide content. The coating on the diamond provided effective protection of the diamond against oxidation by heating in air at 1000 °C for 1 h. Furthermore, the presence of the boron carbide coating also contributed to the maintenance of the static compressive strength during the annealing of diamond in air. PMID:26831205

  14. Corrosion-resistant antifretting coating for the protection of blade locking pieces in GTE compressors and fans

    NASA Astrophysics Data System (ADS)

    Muboyadzhyan, S. A.; Gorlov, D. S.; Egorova, L. P.; Bulavintseva, E. E.

    2014-09-01

    The properties of a corrosion-resistant antifretting coating on EP866Sh steel and VT8M-1 titanium alloy samples are studied. The results of corrosion resistance, heat resistance, fretting resistance, long-term strength, and high-cycle fatigue tests and the results of physical metallurgy and metallographic investigations of the samples with the coating before and after the tests are presented.

  15. Drug Resistance and Pseudoresistance: An Unintended Consequence of Enteric Coating Aspirin

    PubMed Central

    Grosser, Tilo; Fries, Susanne; Lawson, John A.; Kapoor, Shiv C.; Grant, Gregory R.; FitzGerald, Garret A.

    2013-01-01

    Background Low dose aspirin reduces the secondary incidence of myocardial infarction and stroke. Drug resistance to aspirin might result in treatment failure. Despite this concern, no clear definition of “aspirin resistance” has emerged and estimates of its incidence have varied remarkably. We aimed to determine the commonality of a mechanistically consistent, stable and specific phenotype of true pharmacological resistance to aspirin – such as might be explained by genetic causes. Methods and Results Healthy volunteers (n=400) were screened for their response to a single oral dose of 325 mg immediate release or enteric coated aspirin. Response parameters reflected the activity of aspirin's molecular target, cyclooxygenase-1. Individuals who appeared “aspirin resistant” on one occasion underwent repeat testing and if still “resistant” were exposed to low dose enteric coated aspirin (81 mg) and clopidogrel (75 mg) for one week each. Variable absorption caused a high frequency of apparent resistance to a single dose of 325 mg enteric coated aspirin (up to 49%) but not to immediate release aspirin (0%). All individuals responded to aspirin upon repeated exposure, extension of the post dosing interval or addition of aspirin to their platelets ex vivo. Conclusions Pharmacological resistance to aspirin is rare; this study failed to identify a single case of true drug resistance. Pseudoresistance, reflecting delayed and reduced drug absorption, complicates enteric coated but not immediate release aspirin administration. Clinical Trial Registration Information clinicaltrials.gov. Identifier: NCT00948987. PMID:23212718

  16. Improvements in Microstructure and Wear Resistance of Plasma-Sprayed Fe-Based Amorphous Coating by Laser-Remelting

    NASA Astrophysics Data System (ADS)

    Jiang, Chaoping; Chen, Hong; Wang, Gui; Chen, Yongnan; Xing, Yazhe; Zhang, Chunhua; Dargusch, Matthew

    2017-03-01

    Amorphous coating technology is an attractive way of taking advantage of the superior properties of amorphous alloys for structural applications. However, the limited bonds between splats within the plasma-sprayed coatings result in a typically lamellar and porous coating structure. To overcome these limitations, the as-sprayed coating was treated by a laser-remelting process. The microstructure and phase composition of two coatings were analyzed using scanning electron microscopy with energy-dispersive spectroscopy, transmission electron microscopy, and x-ray diffraction. The wear resistance of the plasma-sprayed coating and laser-remelted coating was studied comparatively using a pin-on-disc wear test under dry friction conditions. It was revealed that the laser-remelted coating exhibited better wear resistance because of its defect-free and amorphous-nanocrystalline composited structure.

  17. Corrosion resistance and development length of steel reinforcement with cementitious coatings

    NASA Astrophysics Data System (ADS)

    Pei, Xiaofei

    This research program focused on the corrosion resistance and development length of reinforcing steel coated with Cementitious Capillary Crystalline Waterproofing (CCCW) materials. The first part of this research program involved using the half-cell potential method to evaluate the corrosion resistance of CCCW coating materials. One hundred and two steel bars were embedded in concrete cylinders and monitored. In total, 64 steel reinforcing bars were coated with CCCW prior to embedment, 16 mortar cylinders were externally coated with CCCW, and 22 control (uncoated) samples were tested. All the samples were immersed in a 3.5% concentration chloride solution for a period of one year. Three coating types were studied: CCCW-B, CCCW-B+ C and CCCW-C+D. The test results showed that the CCCW coating materials delayed the corrosion activity to varying degrees. In particular, CCCW-C+D applied on the reinforcing steel surface dramatically delayed the corrosion activity when compared to the control samples. After being exposed to the chloride solution for a period of one year, no sign of corrosion was observed for the cylinders where the concrete surface was coated. The second part of this research evaluated the bond strength and development length of reinforcing steel coated with two types of CCCW coating materials (CCCW-B+C and CCCW-C+D) using a modified pull-out test method. A self-reacting inverted T-shaped beam was designed to avoid compression in the concrete surrounding the reinforcing steel. Steel reinforcing bars were embedded along the web portion of the T-beam with various embedded lengths and were staggered side by side. In total, six T-beams were fabricated and each beam contained 8 samples. Both short-term (7 days) and long-term (3 months) effects of water curing were evaluated. The reinforcing steel bars coated with CCCW-B+C demonstrated a higher bond strength than did samples coated with CCCW-C+D. However, the bond strengths of samples with coating materials

  18. Liquid-oxygen compatible, flame-resistant coating.

    NASA Technical Reports Server (NTRS)

    Bright, C. W.

    1977-01-01

    Polychloroprene rubber composition, using commercially available components, exhibits superior extrusion and durability and is highly flame and corrosion resistant. Material experiences major applications in fields of aeronautics and safety.

  19. Microstructure and Erosion Resistance Performance of ZrAlN/Cu Coating

    NASA Astrophysics Data System (ADS)

    Du, Jun; Zhu, Xiaoying; Zhang, Ping; Cai, Zhihai

    ZrAlN/Cu coating has been deposited onto Ti-6Al-4 V substrate by reactive magnetron sputtering in order to improve its erosion resistance. The morphology and microstructure were studied combined with Field Emission Scanning Electron Microscrope(FSEM), X-ray Diffraction(XRD), X-ray Photoelectron Spectroscopy(XPS) and Transmission Electron Microscopy(TEM). Coatings hardness and toughness were measured by nano-indentation method and Vicker indentation method respectively. It has been found that Zr0.79Al0.19Cu0.02N coating possess dense columnar structure with 20∼40 nm columnar grains exbibiting (100) preferential orientation. XRD reflection peaks slightly shifts to higher angle, showing some of 19at%Al and 2at%Cu substitutely dissolves into face-centered cubic(FCC) ZrN lattice, XPS proves the existence of AlN and Cu phase in coating. Zr0.79Al0.19Cu0.02N coating demonstrates best erosion resistance at 15°∼90° impingement angle compared with Ti6Al4 V substrate, ZrN and Zr0.80Al0.20N coating, attributing to combination of high hardness(40.7 GPa) and good toughness.

  20. Oxidation Resistant, Cr Retaining, Electrically Conductive Coatings on Metallic Alloys for SOFC Interconnects

    SciTech Connect

    Vladimir Gorokhovsky

    2008-03-31

    This report describes significant results from an on-going, collaborative effort to enable the use of inexpensive metallic alloys as interconnects in planar solid oxide fuel cells (SOFCs) through the use of advanced coating technologies. Arcomac Surface Engineering, LLC, under the leadership of Dr. Vladimir Gorokhovsky, is investigating filtered-arc and filtered-arc plasma-assisted hybrid coating deposition technologies to promote oxidation resistance, eliminate Cr volatility, and stabilize the electrical conductivity of both standard and specialty steel alloys of interest for SOFC metallic interconnect (IC) applications. Arcomac has successfully developed technologies and processes to deposit coatings with excellent adhesion, which have demonstrated a substantial increase in high temperature oxidation resistance, stabilization of low Area Specific Resistance values and significantly decrease Cr volatility. An extensive matrix of deposition processes, coating compositions and architectures was evaluated. Technical performance of coated and uncoated sample coupons during exposures to SOFC interconnect-relevant conditions is discussed, and promising future directions are considered. Cost analyses have been prepared based on assessment of plasma processing parameters, which demonstrate the feasibility of the proposed surface engineering process for SOFC metallic IC applications.

  1. 21 CFR 177.1380 - Fluorocarbon resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components...) Chlorotrifluoroethylene-1,1-difluoroethylene-tetrafluoroethylene co-polymer resins produced by copolymerization of..., Extrusion, and Coating Materials,” which is incorporated by reference in accordance with 5 U.S.C. 552(a)...

  2. Thermal stability and oxidation resistance of Ti–Al–N coatings

    PubMed Central

    Chen, Li; Paulitsch, Jörg; Du, Yong; Mayrhofer, Paul H.

    2012-01-01

    Ti1 − xAlxN coatings are widely used for wear resistant applications due to their excellent mechanical and thermal properties, which depend to a great extent on the Al content. Here, we concentrate on a comparative study of the effect of Al content on crystal structure, thermal stability and oxidation resistance of Ti1 − xAlxN coatings. In agreement to earlier studies, thermal annealing of the individual cubic (c) and wurtzite (w) structured metastable Ti1 − xAlxN coatings induces decomposition into their stable phases c-TiN and w-AlN. The decomposition process for c-Ti1 − xAlxN involves an intermediate formation of cubic Al-rich and Ti-rich domains which results in a hardness increase to 34.7 and 34.4 GPa for x = 0.52 and 0.62 when annealed at 950 and 900 °C, respectively. In general, coatings with an Al content closer to the solubility limit, exhibit an earlier decomposition process, and hence an earlier peak-hardness. During exposure of the Ti1 − xAlxN coatings to ambient air at elevated temperatures Al2O3, TiO2 and Al2TiO5 are formed. The oxidation resistance of as-deposited single-phase Ti1 − xAlxN coatings, cubic or wurtzite structured, increases with increasing Al content. However, coatings containing Al contents at the metastable solubility limit, which result in a mixed cubic–wurtzite structure, have the worst oxidation resistance of the Al-containing coatings investigated. The single phase wurtzite structured coating w-Ti0.25Al0.75N shows the best oxidation resistance, with only ~0.7 μm oxide scale thickness, after thermal exposure for 20 h at 850 °C in ambient air. PMID:23471551

  3. High-Frequency Testing of Composite Fan Vanes With Erosion-Resistant Coating Conducted

    NASA Technical Reports Server (NTRS)

    Bowman, Cheryl L.; Sutter, James K.; Naik, Subhash; Otten, Kim D.; Perusek, Gail P.

    2003-01-01

    The mechanical integrity of hard, erosion-resistant coatings were tested using the Structural Dynamics Laboratory at the NASA Glenn Research Center. Under the guidance of Structural Mechanics and Dynamics Branch personnel, fixturing and test procedures were developed at Glenn to simulate engine vibratory conditions on coated polymer-matrix- composite bypass vanes using a slip table in the Structural Dynamics Laboratory. Results from the high-frequency mechanical bench testing, along with concurrent erosion testing of coupons and vanes, provided sufficient confidence to engine-endurance test similarly coated vane segments. The knowledge gained from this program will be applied to the development of oxidation- and erosion-resistant coatings for polymer matrix composite blades and vanes in future advanced turbine engines. Fan bypass vanes from the AE3007 (Rolls Royce America, Indianapolis, IN) gas turbine engine were coated by Engelhard (Windsor, CT) with compliant bond coatings and hard ceramic coatings. The coatings were developed collaboratively by Glenn and Allison Advanced Development Corporation (AADC)/Rolls Royce America through research sponsored by the High-Temperature Engine Materials Technology Project (HITEMP) and the Higher Operating Temperature Propulsion Components (HOTPC) project. High-cycle fatigue was performed through high-frequency vibratory testing on a shaker table. Vane resonant frequency modes were surveyed from 50 to 3000 Hz at input loads from 1g to 55g on both uncoated production vanes and vanes with the erosion-resistant coating. Vanes were instrumented with both lightweight accelerometers and strain gauges to establish resonance, mode shape, and strain amplitudes. Two high-frequency dwell conditions were chosen to excite two strain levels: one approaching the vane's maximum allowable design strain and another near the expected maximum strain during engine operation. Six specimens were tested per dwell condition. Pretest and posttest

  4. Microstructures and Dry Sliding Wear Resistance of the Laser Ceramics Composite Coating on Pure Ti

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Zhang, Yuanbin; Luo, Hui; Huo, Yushuang

    2012-06-01

    In this study, Al-Ti-Co was used to improve the surface performance of pure Ti. Laser cladding is an important surface modification technique, which can be used to improve the surface performance of pure Ti. Laser cladding of the Al-Ti-Co + TiB2 pre-placed powders on pure Ti can form ceramics reinforced the composite coating, which improved the wear resistance of the substrate. Characteristics of the composite coating were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness and wear tests. And the laser-cladded coating can also have major dilution from the substrate. Due to the action of the fine grain strengthening and the phase constituent, the wear resistance and microhardness of pure Ti surface were greatly improved.

  5. Resistance of polysaccharide coatings to proteins, hematopoietic cells, and marine organisms.

    PubMed

    Cao, Xinyu; Pettit, Michala E; Conlan, Sheelagh L; Wagner, Wolfgang; Ho, Anthony D; Clare, Anthony S; Callow, James A; Callow, Maureen E; Grunze, Michael; Rosenhahn, Axel

    2009-04-13

    The interaction of covalently coupled hyaluronic acid, alginic acid, and pectic acid with proteins, cells (hematopoietic KG1a and Jurkat cells), and marine organisms (algal zoospores and barnacle cypris larvae) is compared. In contrast to cells and proteins for which such polysaccharide coatings are known for their antiadhesive properties, marine algal spores and barnacle cyprids were able to colonize the surfaces. Of the three polysaccharides, hyaluronic acid showed the lowest settlement of both Ulva zoopores and barnacles. Photoelectron spectroscopy reveals that the polysaccharide coatings tend to bind bivalent ions, such as calcium, from salt water. Such pretreatment with a high salinity medium significantly changes the protein and hematopoietic cell resistance of the surfaces. Complexation of bivalent ions is therefore considered as one reason for the decreased resistance of polysaccharide coatings when applied in the marine environment.

  6. Effect of Heat Treatment on Wear Resistance of Nickel Aluminide Coatings Deposited by HVOF and PTA

    NASA Astrophysics Data System (ADS)

    Benegra, M.; Santana, A. L. B.; Maranho, O.; Pintaude, G.

    2015-08-01

    This study aims to compare the wear resistance of nickel aluminide coatings deposited using plasma transferred arc (PTA) and high-velocity oxygen fuel (HVOF) processes. Wear resistance was measured in rubber wheel abrasion tests. In both deposition processes, the same raw material (nickel aluminide powder) was atomized and deposited on a 316L steel plate substrate. After deposition, specimens were subjected to thermal cycling, aiming solubilization and precipitation. Coatings deposited using PTA developed different microstructures as a result of the incorporation of substrate elements. However, despite the presence of these microstructures, they performed better than coatings processed using HVOF before the heat treatment. After thermal cycling, the superficial hardness after the wear tests for both processes was similar, resulting in similar mass losses.

  7. Engineering meter-scale laser resistant coatings for the near IR

    SciTech Connect

    Stolz, C J; Adams, J J; Shirk, M D; Norton, M A; Weiland, T L

    2005-08-26

    Laser resistant coatings are needed for beam steering (mirrors), pulse switching (polarizers), and high transport efficiency on environmental barriers (windows/lenses) on large laser systems. A range of defects limit the exposure fluence of these coatings. By understanding the origin and damage mechanisms for these defects, the deposition process can be optimized to realize coatings with greater laser resistance. Electric field modeling can provide insight into which defects are most problematic. Laser damage growth studies are useful for determining a functional laser damage criteria. Mitigation techniques such as micro-machining with a single-crystal diamond cutting tool or short pulse laser ablation using the burst technique can be used to arrest growth in damage sites to extend optic lifetime.

  8. Factors influencing the ballistic impact resistance of elastomer-coated metal substrates

    NASA Astrophysics Data System (ADS)

    Roland, C. M.; Fragiadakis, D.; Gamache, R. M.; Casalini, R.

    2013-02-01

    An experimental study was carried out of various factors affecting the ballistic penetration resistance of elastomer/steel bilayers. For blunt penetrators, the contribution of the coating to performance is optimized using the hardest substrates, front surface placement of the elastomer, and (when normalizing by added weight) thin, ca. 2-3 mm, coatings. These results, none of which are predicted by existing models, evince the marked coupling of coating and substrate in the impact response of the bilayer. We also show that nanoparticle fillers have a modest effect on ballistic performance of polyurea coatings, changing the penetration velocity by a few percent or less. This contrasts with the linear dynamic mechanical behavior, which shows much more significant increases in energy absorption due to nano-reinforcement.

  9. Alkali resistant optical coatings for alkali lasers and methods of production thereof

    DOEpatents

    Soules, Thomas F; Beach, Raymond J; Mitchell, Scott C

    2014-11-18

    In one embodiment, a multilayer dielectric coating for use in an alkali laser includes two or more alternating layers of high and low refractive index materials, wherein an innermost layer includes a thicker, >500 nm, and dense, >97% of theoretical, layer of at least one of: alumina, zirconia, and hafnia for protecting subsequent layers of the two or more alternating layers of high and low index dielectric materials from alkali attack. In another embodiment, a method for forming an alkali resistant coating includes forming a first oxide material above a substrate and forming a second oxide material above the first oxide material to form a multilayer dielectric coating, wherein the second oxide material is on a side of the multilayer dielectric coating for contacting an alkali.

  10. Heat-resistant coatings for niobium and niobium-base alloys (review)

    SciTech Connect

    Dzyadykevich, Y.V.

    1986-06-01

    The author shows that it is possible to formulate the directions in developments whose purpose is to increase the heat resistance of niobium and niobium-base alloys. These include the creation of a barrier layer for retarding undesirable diffusion processes at the coating-base interface, the formation on niobium alloy parts of alloy silicide layers, the obtaining on parts operating at temperatures above 1300 C of a coating of molybdenum disilicide, the application to previously siliconized niobium alloys of a barrier layer of heterophase coatings, the matrix of which is a low-melting component and the filler refractory compounds, and the addition to the oxidizing gaseous medium of various additions increasing the service life of the protective coating.

  11. Applications in the Nuclear Industry for Corrosion-Resistant Amorphous-Metal Thermal-Spray Coatings

    SciTech Connect

    Farmer, J; Choi, J

    2007-07-18

    Amorphous metal and ceramic thermal spray coatings have been developed that can be used to enhance the corrosion resistance of containers for the transportation, aging and disposal of spent nuclear fuel and high-level radioactive wastes. Fe-based amorphous metal formulations with chromium, molybdenum and tungsten have shown the corrosion resistance believed to be necessary for such applications. Rare earth additions enable very low critical cooling rates to be achieved. The boron content of these materials, and their stability at high neutron doses, enable them to serve as high efficiency neutron absorbers for criticality control. Ceramic coatings may provide even greater corrosion resistance for container applications, though the boron-containing amorphous metals are still favored for criticality control applications. These amorphous metal and ceramic materials have been produced as gas atomized powders and applied as near full density, non-porous coatings with the high-velocity oxy-fuel process. This paper summarizes the performance of these coatings as corrosion-resistant barriers, and as neutron absorbers. Relevant corrosion models are also discussed, as well as a cost model to quantify the economic benefits possible with these new materials.

  12. Wear-resistant ball bearings for space applications. [coated with titanium carbide

    NASA Technical Reports Server (NTRS)

    Boving, H.; Hintermann, H. E.; Haenni, W.; Bondivenne, E.; Boeto, M.; Conde, M.

    1977-01-01

    Ball bearings for hostile environments were developed. They consist of normal ball bearing steel parts of which the rings are coated with hard, wear-resistant, chemical vapor deposited (C.V.D) TiC. Experiments in ultrahigh vacuum, using cages of various materials with self-lubricating properties, have shown that such bearings are suitable for space applications.

  13. Oxidation resistant coating for titanium alloys and titanium alloy matrix composites

    NASA Technical Reports Server (NTRS)

    Brindley, William J. (Inventor); Smialek, James L. (Inventor); Rouge, Carl J. (Inventor)

    1992-01-01

    An oxidation resistant coating for titanium alloys and titanium alloy matrix composites comprises an MCrAlX material. M is a metal selected from nickel, cobalt, and iron. X is an active element selected from Y, Yb, Zr, and Hf.

  14. Biocidal activity of metalloacid-coated surfaces against multidrug-resistant microorganisms

    PubMed Central

    2012-01-01

    Background The antimicrobial effects of a coating of molybdenum trioxide (MoO3) has been recently described. The metalloacid material produces oxonium ions (H3O+), which creates an acidic pH that is an effective, non specific antimicrobial. We determined the in vitro antimicrobial activity of molybdenum trioxide metalloacid-coated surfaces. Methods Metalloacid-coated and non-coated (control) surfaces were contaminated by exposing them for 15 minutes to microbial suspensions containing 105 cfu/mL. Eleven microorganisms responsible for nosocomial infections were tested: two Staphylococcus aureus strains (the hetero-vancomycin intermediate MRSA Mu50 strain and a ST80-PVL-producing MRSA strain); a vancomycin-resistant vanA Enterococcus faecium strain; three extended-spectrum beta-lactamase-producing Enterobacteriaceae strains; a MBL-producing Pseudomonas aeruginosa strain; a multidrug-resistant Acinetobacter baumannii strain; a toxin-producing Clostridium difficile strain; and two fungi (Candida albicans and Aspergillus fumigatus). The assay tested the ability of the coated surfaces to kill microorganisms. Results Against all non-sporulating microorganisms tested, metalloacid-coated surfaces exhibited significant antimicrobial activity relative to that of the control surfaces within two to six hours after contact with the microorganisms (p < 0.001). Microorganism survival on the coated surfaces was greatly impaired, whereas microorganism survival on control surfaces remained substantial. Conclusions We suggest that, facing the continuing shedding of microorganisms in the vicinity of colonized or infected patients, the continuous biocidal effect of hydroxonium oxides against multidrug-resistant microorganisms may help limit environmental contamination between consecutive cleaning procedures. PMID:23148568

  15. Effect of the deposition temperature on corrosion resistance and biocompatibility of the hydroxyapatite coatings

    NASA Astrophysics Data System (ADS)

    Vladescu, A.; Braic, M.; Azem, F. Ak; Titorencu, I.; Braic, V.; Pruna, V.; Kiss, A.; Parau, A. C.; Birlik, I.

    2015-11-01

    Hydroxyapatite (HAP) ceramics belong to a class of calcium phosphate-based materials, which have been widely used as coatings on titanium medical implants in order to improve bone fixation and thus to increase the lifetime of the implant. In this study, HAP coatings were deposited from pure HAP targets on Ti6Al4V substrates using the radio-frequency magnetron sputtering technique at substrate temperatures ranging from 400 to 800 °C. The surface morphology and the crystallographic structure of the films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion resistance of the coatings in saliva solution at 37 °C was evaluated by potentiodynamic polarization. Additionally, the human osteosarcoma cell line (MG-63) was used to test the biocompatibility of the coatings. The results showed that all of the coatings grown uniformly and that the increasing substrate temperature induced an increase in their crystallinity. Corrosion performance of the coatings was improved with the increase of the substrate temperature from 400 °C to 800 °C. Furthermore, all the coatings support the attachment and growth of the osteosarcoma cells with regard to the in vitro test findings.

  16. Laser-Assisted Cold-Sprayed Corrosion- and Wear-Resistant Coatings: A Review

    NASA Astrophysics Data System (ADS)

    Olakanmi, E. O.; Doyoyo, M.

    2014-06-01

    Laser-assisted cold spray (LACS) process will be increasingly employed for depositing coatings because of its unique advantages: solid-state deposition of dense, homogeneous, and pore-free coatings onto a range of substrates; and high build rate at reduced operating costs without the use of expensive heating and process inert gases. Depositing coatings with excellent performance indicators via LACS demands an accurate knowledge and control of processing and materials' variables. By varying the LACS process parameters and their interactions, the functional properties of coatings can be manipulated. Moreover, thermal effect due to laser irradiation and microstructural evolution complicate the interpretation of LACS mechanical deformation mechanism which is essential for elucidating its physical phenomena. In order to provide a basis for follow-on-research that leads to the development of high-productivity LACS processing of coatings, this review focuses on the latest developments in depositing corrosion- and wear-resistant coatings with the emphasis on the composition, structure, and mechanical and functional properties. Historical developments and fundamentals of LACS are addressed in an attempt to describe the physics behind the process. Typical technological applications of LACS coatings are also identified. The investigations of all process sequences, from laser irradiation of the powder-laden gas stream and the substrate, to the impingement of thermally softened particles on the deposition site, and subsequent further processes, are described. Existing gaps in the literature relating to LACS-dependent microstructural evolution, mechanical deformation mechanisms, correlation between functional properties and process parameters, processing challenges, and industrial applications have been identified in order to provide insights for further investigations and innovation in LACS deposition of wear- and corrosion-resistant coatings.

  17. Corrosion-resistant front surface aluminum mirror coatings

    NASA Astrophysics Data System (ADS)

    Guenther, Karl H.; Penny, Iain; Willey, Ronald R.

    1993-03-01

    Front surface metal mirrors need protection of the inherently fragile metal film deposited on a glass substrate. Conventional evaporated dielectric thin-film overcoats provide limited protection because of their less than dense packing. These films usually have a columnar structure with voids between the columns. The voids give access to the underlying metal film for humidity and corrosive gases or liquids. Some progress in developing better coatings was made in the early 1980s with ion-assisted deposition. Front surface aluminum mirrors with dielectric thin films deposited by reactive low-voltage ion plating have a still higher survival time, by a factor of up to three under comparable test conditions. The transmission of our best samples increased to only 10 percent when immersed in 0.2 M NaOH for 20 h. By comparison, an unprotected aluminum film dissolves in less than 5 min. Electron beam evaporated dielectric coatings provide protection for about 1.5 to 2 h in the same test solution. The reason for the significant improvement brought about by reactive low-voltage ion plating deposition, and its advantage for large-scale production is discussed.

  18. Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems

    SciTech Connect

    Gopala N. Krishnan; Ripudaman Malhotra; Esperanza Alvarez; Kai-Hung Lau; Jordi Perez-Mariano; Angel Sanjurjo

    2006-06-30

    Heat-exchangers, particle filters, turbines, and other components in integrated coal gasification combined cycle system must withstand the highly sulfiding conditions of the high-temperature coal gas over an extended period of time. The performance of components degrades significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low-cost alloy may improve its resistance to such sulfidation attack, and decrease capital and operating costs. The alloys used in the gasifier service include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive nickel-cobalt alloys. During this period, we analyzed several coated and exposed samples of 409 steel by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). We report here on findings of this analysis: (1) A SS409 coupon that was coated with multilayered combined nitrides of Ti, Al, and Si showed adherent coatings on the surface; (2) A similarly coated coupon, after exposure to simulated coal gas at 900 C for 300 h, revealed that the coating has cracked during the exposure; (3) An SS409 coupon that was coated with nitrides of Ti and Si with a barrier layer of tungsten in between to improve the adhesion of the coating and to prevent outward diffusion of iron to the surface. (4) A porous coupon was coated with nitrides of Ti and Al and examination of the coupon revealed deposition of Ti at the interior surfaces. A similarly prepared coupon was exposed to simulated coal gas at 370 C for 300 h, and it showed no corrosion.

  19. Nanoenhanced polyurea as a blast resistant coating for concrete masonry walls

    NASA Astrophysics Data System (ADS)

    Rivera, Heather Kathryn Daniell

    Blast impact is a major concern in the world today. The leading cause of death due to blast impacts is rapidly moving debris. To prevent this many researchers are looking for methods of improved blast resistance for concrete masonry walls. However, many available protective coatings are not flame retardant. This thesis focuses on nanoenhanced polyurea for applications in improving blast resistance, while possessing improved flame retardancy, of concrete masonry walls. The polyurea that is being researched is enhanced with nanoadditives in an effort improve both blast and fire resistance. These materials are dynamically tested and those showing marked improvement are chosen for experimental and computational testing.

  20. Novel heat-resistance UV curable waterborne polyurethane coatings modified by melamine

    NASA Astrophysics Data System (ADS)

    Fang, Z. H.; Duan, H. Y.; Zhang, Z. H.; Wang, J.; Li, D. Q.; Huang, Y. X.; Shang, J. J.; Liu, Z. Y.

    2011-03-01

    Novel UV curable waterborne polyurethane coatings (UVWPU) modified by melamine was prepared using isophorone diisocyanate (IPDI), polyethylene glycol (PEG), α,α-dimethylol propionic acid (DMPA), hydroxyethyl acrylate (HEA) as main materials. Copolymer structure was verified using Fourier transform infrared spectroscopy (FT-IR). Performance of the coatings was evaluated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), and mechanical tests such as pencil hardness and resistance to water. The results showed that the modified UVWPU film had the good thermal resistance, water resistance and mechanical properties. The optimum melamine dosage was 4.70 wt.%, the glass transition temperature ( Tg) of the modified film increased by 20.4 °C and 5% weight-loss temperature (253 °C) increased by 105 °C. No change color, crinkle, desquamate, dehisce and frothy were found after the modified film dried at 130 °C for 2 h.

  1. Significance of thermal contact resistance in two-layer thermal-barrier-coated turbine vanes

    NASA Technical Reports Server (NTRS)

    Liebert, C. H.; Gaugler, R. E.

    1980-01-01

    The importance of thermal contact resistance between layers in heat transfer through two layer, plasma sprayed, thermal barrier coatings applied to turbine vanes was investigated. Results obtained with a system of NiCrAlY bond and yttria stabilized zirconia ceramic show that thermal contact resistance between layers is negligible. These results also verified other studies which showed that thermal contact resistance is negligible for a different coating system of NiCr bond calcia stabilized zirconia ceramic. The zirconia stabilized ceramic thermal conductivity data scatter presented in the literature is ?20 to -10 percent about a curve fit of the data. More accurate predictions of heat transfer and metal wall temperatures are obtained when the thermal conductivity values are used at the ?20 percent level.

  2. Thermal Shock Resistance of Stabilized Zirconia/Metal Coat on Polymer Matrix Composites by Thermal Spraying Process

    NASA Astrophysics Data System (ADS)

    Zhu, Ling; Huang, Wenzhi; Cheng, Haifeng; Cao, Xueqiang

    2014-12-01

    Stabilized zirconia/metal coating systems were deposited on the polymer matrix composites by a combined thermal spray process. Effects of the thicknesses of metal layers and ceramic layer on thermal shock resistance of the coating systems were investigated. According to the results of thermal shock lifetime, the coating system consisting of 20 μm Zn and 125 μm 8YSZ exhibited the best thermal shock resistance. Based on microstructure evolution, failure modes and failure mechanism of the coating systems were proposed. The main failure modes were the formation of vertical cracks and delamination in the outlayer of substrate, and the appearance of coating spallation. The residual stress, thermal stress and oxidation of substrate near the substrate/metal layer interface were responsible for coating failure, while the oxidation of substrate near the substrate/coating interface was the dominant one.

  3. Electroless Ni-P-PTFE-Al2O3 Dispersion Nanocomposite Coating for Corrosion and Wear Resistance

    NASA Astrophysics Data System (ADS)

    Sharma, Ankita; Singh, A. K.

    2014-01-01

    With the aim to produce a coating having good corrosion and wear resistance alongside hardness but lesser friction coefficient, Ni-P-PTFE-Al2O3 (NiPPA) dispersion coating was developed. This was achieved by introducing nanosized polytetrafluoroethylene (PTFE) and alumina (Al2O3) in the Ni-P matrix deposited on mild steel substrate. The coating was characterized using scanning electron microscopy, energy dispersive analysis of x-ray, and x-ray diffractrometry. Microhardness and wear resistance of the coating was measured using Vicker's hardness tester and Pin-on-Disc method, respectively. The corrosion behavior was measured using electrochemical polarization and immersion tests with and without exposure in 3.5% NaCl solution. It is observed that codeposition of Al2O3 and PTFE particles with Ni-P coating results in comparatively smooth surface with nodular grains. The NiPPA coating was observed to have moderate hardness between electroless Ni-P-PTFE and Ni-P-Al2O3 coating and good wear resistance with lubricating effect. Addition of both PTFE and Al2O3 is observed to enhance corrosion resistance of the Ni-P coating. However, improvement in corrosion resistance is more due to addition of Al2O3 than PTFE. Continuous exposure for 10-20 days in corrosive solution is found to deteriorate corrosion protection properties of the coating.

  4. The heat resistance of a polyurethane coating filled with modified nano-CaCO3

    NASA Astrophysics Data System (ADS)

    Li, Bin; Li, Song-Mei; Liu, Jian-Hua; Yu, Mei

    2014-10-01

    The modification of polyurethane coating by adding surface-modified CaCO3 nanoparticles (nano-CaCO3) was investigated in this paper. To improve interfacial interaction between the nano-CaCO3 and the polyurethane (PU) matrix, a silane coupling agent (KH560) was used to modify the nano-CaCO3. The grafting of KH560 on the nano-CaCO3 surfaces was characterized by the TEM, FTIR and TGA techniques. The modification of the nano-CaCO3 surfaces with KH560 was demonstrated to improve the dispersity of nano-CaCO3. FTIR, SEM and AFM were used to characterize the polyurethane coating. The FTIR spectrum indicated that the modification of nano-CaCO3 does not influence the chemical structure of the PU matrix. The roughness and gloss of the nanocomposite coatings containing various amount of nano-CaCO3 were evaluated using a roughness tester and a brightness meter. The heat resistance of the polyurethane coating containing various amounts of nano-CaCO3 was evaluated using the TGA technique. The results revealed that nano-CaCO3 treatment with KH560 improves the nanoparticle dispersion and heat-resistance of polyurethane coating.

  5. Preparation and corrosion resistance of pulse electrodeposited Zn and Zn-SiC nanocomposite coatings

    NASA Astrophysics Data System (ADS)

    Sajjadnejad, M.; Mozafari, A.; Omidvar, H.; Javanbakht, M.

    2014-05-01

    Pure Zn and Zn matrix composite coatings containing nano-sized SiC particles with an average size of 50 nm were prepared from the zinc sulfate bath. The effects of the pulse frequency, maximum current density and duty cycle on the amount of particles embedded were examined. Electron microscopic studies revealed that the coating morphology was modified by the presence of SiC nanoparticles. In the presence of SiC nanoparticles deposit grows in outgrowth mode resulting in a very rough and porous microstructure. However, at very low and very high duty cycles a smooth and pore free microstructure was obtained. Corrosion resistance properties of the coatings were studied using potentiodynamic polarization technique in 1 M NaCl solution. It was established that presence of well-dispersed nanoparticles significantly improves corrosion resistance of the zinc by filling gaps and defects between zinc flakes and leading to a smoother surface. However, presence of the SiC nanoparticles led to a mixed microstructure with fine and coarse zinc flakes in some coatings, which presented a weak corrosion behavior. Incorporation of SiC nanoparticles enhanced hardness of the Zn coatings by fining deposit structure and through the dispersion hardening effect.

  6. The effect of Teflon coating on the resistance to sliding of orthodontic archwires.

    PubMed

    Farronato, Giampietro; Maijer, Rolf; Carìa, Maria Paola; Esposito, Luca; Alberzoni, Dario; Cacciatore, Giorgio

    2012-08-01

    Teflon is an anti-adherent and aesthetic material. The aim of this study was to evaluate, in vitro, the influence of Teflon coating on the resistance to sliding (RS) of orthodontic archwires. For this purpose, Teflon-coated archwires were examined using frictional resistance tests by means of a universal testing machine and compared with conventional uncoated wires. Twelve types of archwires with round and rectangular sections (0.014, 0.018, and 0.018 × 0.025 inches) and of different materials (stainless steel and nickel-titanium) were tested with two passive self-ligating brackets (SmartClip™ and Opal(®)) and one active self-ligating bracket (Quick(®)). Each archwire-bracket combination was tested 10 times under 8 simulated clinical scenarios. Statistical comparisons were conducted between the uncoated and Teflon-coated archwires using Wilcoxon and Mann-Whitney tests, and linear regression analysis. For all bracket-archwire combinations, Teflon-coated archwires resulted lower friction than the corresponding uncoated archwires (P < 0.01). The results showed that Teflon coating has the potential to reduce RS of orthodontic archwires.

  7. Electrical resistivity and dielectric properties of helical microorganism cells coated with silver by electroless plating

    NASA Astrophysics Data System (ADS)

    Cai, Jun; Lan, Mingming; Zhang, Deyuan; Zhang, Wenqiang

    2012-09-01

    In this paper, microorganism cells (Spirulina platens) were used as forming templates for the fabrication of the helical functional particles by electroless silver plating process. The morphologies and ingredients of the coated Spirulina cells were analyzed with scanning electron microscopy and energy dispersive spectrometer. The crystal structures were characterized by employing the X-ray diffraction. The electrical resistivity and dielectric properties of samples containing different volume faction of sliver-coated Spirulina cells were measured and investigated by four-probe meter and vector network analyzer. The results showed that the Spirulina cells were successfully coated with a uniform silver coating and their initial helical shapes were perfectly kept. The electrical resistivity and dielectric properties of the samples had a strong dependence on the volume content of sliver-coated Spirulina cells and the samples could achieve a low percolation value owing to high aspect ratio and preferable helical shape of Spirulina cells. Furthermore, the conductive mechanism was analyzed with the classic percolation theory, and the values of ϕ and t were obtained.

  8. 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)

  9. Reaction of uranium and the fluorocarbon FC-75

    NASA Astrophysics Data System (ADS)

    Young, R. H.

    1985-04-01

    Because of criticality concerns with water cooling in enriched uranium upgrading, a fluorocarbon has been evaluated as a replacement coolant for internal module components in the Plasma Separation Process (PSP). The interaction of bulk uranium and of powdered uranium with FC-75 has been investigated at temperatures between 200 and 700 C. The gas pressure and the metal temperature were monitored as a function of time. Modest temperature changes of 50 to 100 C were observed for the bulk uranium/fluorocarbon reaction. Much larger changes (up to 1000 C) were noted for the reaction involving high surface area uranium powder. These temperature transients, particularly for the powdered uranium reaction, were short-lived ( 10 seconds) and indicative of the formation of a protective layer of reaction products. Analysis of residual gas products by infrared spectroscopy indicated that one potentially serious hazard, UF6, was not present; however, several small toxic fluorocarbons were produced by thermolysis and/or reaction. X-ray diffraction analysis of the residual solids indicated UF4 and UO2 were the major solid products.

  10. Using CrAIN Multilayer Coatings to Improve Oxidation Resistance of Steel Interconnects for Solid Oxide Fuel Cell Stacks

    SciTech Connect

    Smith, Richard J.; Tripp, C.; Knospe, Anders; Ramana, C. V.; Gorokhovsky, Vladimir I.; Shutthanandan, V.; Gelles, David S.

    2004-06-01

    The requirements of low cost and high-tempurature corrosion resistance for bipolar interconnect plates in solid oxide fuel cell stacks has directed attention to the use of metal plates with oxidation resistant coatings. We have investigatedt he performance of steel plates with multilayer coatings consisting of CrN for electrical conductivity and CrAIN for oxidation resistance. The coatings were deposited usin large area filterd arc deposition technolgy, and subsequently annealed in air for up to 25 hours at 800 degrees celsius. The composition, structer and morphology of the coated plates were characterized using RBS, nuclear reaction analysis, AFM and TEM techniques. By altering the architecture of the layers within the coatings, the rate of oxidation was reduced by more than an order of magnitute. Electrical resistance was measured at room temperature.

  11. Hierarchical ZnO particles grafting by fluorocarbon polymer derivative: Preparation and superhydrophobic behavior

    NASA Astrophysics Data System (ADS)

    Gao, Dahai; Jia, Mengqiu

    2015-07-01

    Superhydrophobic surfaces on the basis of hierarchical ZnO particles grafted by fluoroethylene-vinylether (FEVE) polymer derivative were prepared using a facile, mild and low-cost method. X-ray diffraction (XRD) and scanning electron microscope (SEM) revealed that the resulting ZnO particles via hydrothermal process exhibit micro-nano dual-scale morphology with high purity under a suitable surfactant amount and alkali concentration. The grafting of FEVE derivative was confirmed by Fourier transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectrometer (EDS), suggesting that hierarchical surface of ZnO particles was an imported monomolecular layer of fluorocarbon polymer. The obtained surface fabricated by drop-casting shows considerably high contact angle and good resistance to water immersion. The wetting behavior in this work was furthermore analyzed by theoretical wetting model. This work demonstrates that the sufficient low-wettable surface and high roughness both take a vital role in the superhydrophobic behavior.

  12. Tungsten coating for improved wear resistance and reliability of microelectromechanical devices

    DOEpatents

    Fleming, James G.; Mani, Seethambal S.; Sniegowski, Jeffry J.; Blewer, Robert S.

    2001-01-01

    A process is disclosed whereby a 5-50-nanometer-thick conformal tungsten coating can be formed over exposed semiconductor surfaces (e.g. silicon, germanium or silicon carbide) within a microelectromechanical (MEM) device for improved wear resistance and reliability. The tungsten coating is formed after cleaning the semiconductor surfaces to remove any organic material and oxide film from the surface. A final in situ cleaning step is performed by heating a substrate containing the MEM device to a temperature in the range of 200-600 .degree. C. in the presence of gaseous nitrogen trifluoride (NF.sub.3). The tungsten coating can then be formed by a chemical reaction between the semiconductor surfaces and tungsten hexafluoride (WF.sub.6) at an elevated temperature, preferably about 450.degree. C. The tungsten deposition process is self-limiting and covers all exposed semiconductor surfaces including surfaces in close contact. The present invention can be applied to many different types of MEM devices including microrelays, micromirrors and microengines. Additionally, the tungsten wear-resistant coating of the present invention can be used to enhance the hardness, wear resistance, electrical conductivity, optical reflectivity and chemical inertness of one or more semiconductor surfaces within a MEM device.

  13. Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems

    SciTech Connect

    Gopala N. Krishnan; Ripudaman Malhotra; Esperanza Alvarez; Kai-Hung Lau; Angel Sanjurjo

    2006-01-01

    Heat-exchangers, particle filters, turbines, and other components in integrated coal gasification combined cycle system must withstand the highly sulfiding conditions of the high-temperature coal gas over an extended period of time. The performance of components degrades significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low-cost alloy may improve its resistance to such sulfidation attack, and decrease capital and operating costs. The alloys used in the gasifier service include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive nickel-cobalt alloys. During this period we tested coated alloy coupons under conditions designed to mimic the conditions in the filter unit after the high-temperature heat recovery unit (HTHRU). The filter unit is another important area where corrosion has caused unscheduled downtime, and the remedy has been the use of sintered metal tubes made of expensive alloys such as inconel. The objective of our test was to determine if those coatings on 400-series steel that were not able to withstand the harsher conditions of the HTHRU, may be sufficiently resistant for use in the filter unit, at the reduced temperatures. Indeed, most of our coatings survived well; the exceptions were the coated porous samples of SS316. We continued making improvements to our coatings apparatus and the procedure began during the last quarter. As a result of these modifications, the coupons we are now producing are uniform. We describe the improved procedure for preparing diffusion coatings. Finally, because porous samples of steel in grades other than SS316 are not readily available, we also decided to procure SS409 powder and fabricate our own sintered porous coupons.

  14. The Effect of Zirconium Addition on the Oxidation Resistance of Aluminide Coatings

    NASA Astrophysics Data System (ADS)

    Zagula-Yavorska, Maryana; Pytel, Maciej; Romanowska, Jolanta; Sieniawski, Jan

    2015-04-01

    Nickel, Mar M247, and Mar M200 superalloys were coated with zirconium-doped aluminide deposited by the chemical vapor deposition method. All coatings consisted of two layers: an additive one, comprising of the β-NiAl phase and the interdiffusion one. The interdiffusion layer on pure nickel consisted of the γ'-Ni3Al phase and β-NiAl phase on superalloys. Precipitations of zirconium-rich particles were found near the coating's surface and at the interface between the additive and the interdiffusion layer. Zirconium doping of aluminide coating improved the oxidation resistance of aluminide coatings deposited both on the nickel substrate and on the Mar M200 superalloy. Precipitations of ZrO2 embedded by the Al2O3 oxide were formed during oxidation. It seems that the ZrO2 oxide increases adhesion of the Al2O3 oxide to the coating and decreases the propensity of the Al2O3 oxide rumpling and spalling.

  15. Concentrated polymer brush-modified silica particle coating confers biofouling-resistance on modified materials.

    PubMed

    Yoshikawa, Chiaki; Qiu, Jun; Shimizu, Yoshihisa; Huang, Chih-Feng; Gelling, Onko-Jan; van den Bosch, Edith

    2017-01-01

    Biofouling, an undesired adsorption of biological material to otherwise inert surfaces, is detrimental in medical, pharmaceutical, and other sectors. Concentrated polymer brushes (CPB) confer non-biofouling properties on modified surfaces but are cumbersome to fabricate. Here, a simple and versatile method of fabricating non-biofouling coatings for various substrates was developed using CPB-modified silica nanoparticles (SiPs). Concentrated poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA) brushes were grafted on SiPs by surface-initiated atom transfer radical polymerization. CPB-SiPs were spin-coated onto silicon wafers or quartz crystal microbalance (QCM) sensor chips with phenyl azido cross-linkers. SiP cross-linking was then performed by ultra violet irradiation for 20s, or by heating at 120°C for 12h. Protein adsorption to coatings was studied by QCM approach and human umbilical vein endothelial cell adhesion to coatings was examined. SiP to cross-linker weight ratios were varied from 2.0/0.5 to 9.0/0.5 (wt/wt%) and the coatings almost completely suppressed protein adsorption and cell adhesion to treated surfaces. The coating was also applied to polymeric films, rendering these materials biofouling-resistant.

  16. Design of barrier coatings on kink-resistant peripheral nerve conduits

    PubMed Central

    Clements, Basak Acan; Bushman, Jared; Murthy, N Sanjeeva; Ezra, Mindy; Pastore, Christopher M; Kohn, Joachim

    2016-01-01

    Here, we report on the design of braided peripheral nerve conduits with barrier coatings. Braiding of extruded polymer fibers generates nerve conduits with excellent mechanical properties, high flexibility, and significant kink-resistance. However, braiding also results in variable levels of porosity in the conduit wall, which can lead to the infiltration of fibrous tissue into the interior of the conduit. This problem can be controlled by the application of secondary barrier coatings. Using a critical size defect in a rat sciatic nerve model, the importance of controlling the porosity of the nerve conduit walls was explored. Braided conduits without barrier coatings allowed cellular infiltration that limited nerve recovery. Several types of secondary barrier coatings were tested in animal studies, including (1) electrospinning a layer of polymer fibers onto the surface of the conduit and (2) coating the conduit with a cross-linked hyaluronic acid-based hydrogel. Sixteen weeks after implantation, hyaluronic acid-coated conduits had higher axonal density, displayed higher muscle weight, and better electrophysiological signal recovery than uncoated conduits or conduits having an electrospun layer of polymer fibers. This study indicates that braiding is a promising method of fabrication to improve the mechanical properties of peripheral nerve conduits and demonstrates the need to control the porosity of the conduit wall to optimize functional nerve recovery. PMID:26977288

  17. High Density Infrared (HDI) Transient Liquid Coatings for Improved Wear and Corrosion Resistance

    SciTech Connect

    Ronald W. Smith

    2007-07-05

    This report documents a collaborative effort between Oak Ridge National Laboratory (ORNL), Materials Resources International and an industry team of participants to develop, evaluate and understand how high density infrared heating technology could be used to improve infiltrated carbide wear coatings and/or to densify sprayed coatings. The research included HDI fusion evaluations of infiltrated carbide suspensions such (BrazeCoat® S), composite suspensions with tool steel powders, thermally sprayed Ni-Cr- B-Si (self fluxing alloy) and nickel powder layers. The applied work developed practical HDI / transient liquid coating (TLC) procedures on test plates that demonstrated the ability to fuse carbide coatings for industrial applications such as agricultural blades, construction and mining vehicles. Fundamental studies helped create process models that led to improved process understanding and control. The coating of agricultural blades was demonstrated and showed the HDI process to have the ability to fuse industrial scale components. Sliding and brasive wear tests showed that high degree of wear resistance could be achieved with the addition of tool steel powders to carbide particulate composites.

  18. Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems

    SciTech Connect

    Gopala N. Krishnan; Ripudaman Malhotra; Esperanza Alvarez; Kai-Hung Lau; Angel Sanjurjo

    2005-09-01

    Heat-exchangers, particle filters, turbines, and other components in integrated coal gasification combined cycle system must withstand the highly sulfiding conditions of the high-temperature coal gas over an extended period of time. The performance of components degrades significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low-cost alloy may improve its resistance to such sulfidation attack, and decrease capital and operating costs. The alloys used in the gasifier service include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive nickel-cobalt alloys. During this reporting period, we conducted several exposure tests with coated and uncoated coupons including a ''500-h'' test. The first experiment was a 316-h test and was designed to look at the performance of Ti/Ta nitride coatings, which seemed to fare the best in earlier tests. The next experiment was a 112-h test with a range of pure metals and commercially available materials. Its purpose was to help identify those metals that best withstood gasifier environment, and hence should be good ingredients for coatings. Finally, we ran a ''500-h'' test, which was also our milestone, with coupons coated with Ti/Ta nitride or Cr/Al coatings.

  19. Mussel-inspired modification of dextran for protein-resistant coatings of titanium oxide.

    PubMed

    Park, Jae Yoon; Kim, Jee Seon; Nam, Yoon Sung

    2013-09-12

    Surface modification of inorganic materials to prevent non-specific protein adsorption is critically important for developing a biocompatible materials' platform for medical implantation, diagnostics, and therapeutics. Here we report mussel-inspired chemical modification of dextran for anti-fouling coatings of metal oxide. Catechols are conjugated to dextran via a carbamate ester linkage, producing catechol-grafted dextran with a grafting density of 7.3 mol.%. Titanium dioxide (TiO₂) is coated with the catechol-grafted dextran, and the anti-fouling effect of dextran coatings is examined by using the adsorption of human serum albumin. The mussel-inspired dextran coatings show excellent resistance to non-specific protein adsorption: the adsorption equilibrium constant (K) is 0.69 Lg(-1) for dextran-coated TiO₂ while that for pristine TiO₂ surface is 3.53 Lg(-1). This study suggests that catechol-grafted dextran is a promising material for effective anti-fouling coatings of implantable inorganic materials.

  20. Pressure vessel with impact and fire resistant coating and method of making same

    NASA Technical Reports Server (NTRS)

    DeLay, Thomas K. (Inventor)

    2005-01-01

    An impact and fire resistant coating laminate is provided which serves as an outer protective coating for a pressure vessel such as a composite overwrapped vessel with a metal lining. The laminate comprises a plurality of fibers (e.g., jute twine or other, stronger fibers) which are wound around the pressure vessel and an epoxy matrix resin for the fibers. The epoxy matrix resin including a plurality of microspheres containing a temperature responsive phase change material which changes phase in response to exposure thereof to a predetermined temperature increase so as to afford increased insulation and heat absorption.

  1. Pressure Vessel with Impact and Fire Resistant Coating and Method of Making Same

    NASA Technical Reports Server (NTRS)

    DeLay, Thomas K. (Inventor)

    2005-01-01

    An impact and fire resistant coating laminate is provided which serves as an outer protective coating for a pressure vessel such as a composite overwrapped vessel with a metal lining. The laminate comprises a plurality of fibers (e.g., jute twine or other, stronger fibers) which are wound around the pressure vessel and an epoxy matrix resin for the fibers. The epoxy matrix resin including a plurality of microspheres containing a temperature responsive phase change material which changes phase in response to exposure thereof to a predetermined temperature increase so as to afford increased insulation and hear absorption.

  2. Assessment of Erosion Resistance of Coated Polymer Matrix Composites for Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Sutter, James K.; Horan, Richard A.; Naik, Subhash K.; Cupp, Randall J.

    2004-01-01

    The erosion behavior of tungsten carbide-cobalt (WC-Co) coated and uncoated polymer matrix composites (PMCs) was examined with solid particle impingement using air jets. Erosion tests were conducted with Arizona road dust impinging at 20 degrees, 60 degrees, and 90 degrees angles at a velocity of 229 meters per second at both 294 and 366 K. Noncontact optical profilometry was used to measure the wear volume loss. Results indicate that the WC-Co coating enhanced erosion resistance and reduced erosion wear volume loss by a factor of nearly 2. This should contribute to longer wear lives, reduced related breakdowns, decreased maintenance costs, and increased product reliability.

  3. Development of a protective decorative fire resistant low smoke emitting, thermally stable coating material

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The development of suitable electrocoatings and subsequent application to nonconductive substrates are discussed. Substrates investigated were plastics or resin-treated materials such as FX-resin (phenolic-type resin) impregnated fiberglass mat, polyphenylene sulfide, polyether sulfone and polyimide-impregnated unidirectional fiberglass. Efforts were aimed at formulating a fire-resistant, low smoke emitting, thermally stable, easily cleaned coating material. The coating is to be used for covering substrate panels, such as aluminum, silicate foam, polymeric structural entities, etc., all of which are applied in the aircraft cabin interior and thus subject to the spillages, scuffing, spotting and the general contaminants which prevail in aircraft passenger compartments.

  4. Corrosion-resistant multilayer coatings for the 28-75 nm wavelength region

    SciTech Connect

    Soufli, R; Fernandez-Perea, M; Al, E T

    2011-11-08

    Corrosion has prevented use of SiC/Mg multilayers in applications requiring good lifetime stability. We have developed Al-based barrier layers that dramatically reduce corrosion, while preserving high reflectance and low stress. The aforementioned advances may enable the implementation of corrosion-resistant, high-performance SiC/Mg coatings in the 28-75 nm region in applications such as tabletop EUV/soft x-ray laser sources and solar physics telescopes. Further study and optimization of corrosion barrier structures and coating designs is underway.

  5. Protection of 2024-T3 aluminium alloy by corrosion resistant phytic acid conversion coating

    NASA Astrophysics Data System (ADS)

    Shi, Hongwei; Han, En-Hou; Liu, Fuchun; Kallip, Silvar

    2013-09-01

    The corrosion protection properties of environmentally friendly phytic acid conversion coatings were studied on 2024-T3 aluminium alloy. The films were prepared under acidic conditions with various pH values and characterised by SEM, EDS, ATR-FTIR and electrochemical techniques. The results indicate that the conversion coatings obtained by immersing the alloy in phytic acid solutions at pH from 3 to 5.5 provide excellent corrosion resistance. ATR-FTIR confirms that the film is formed by deposition of reaction products between Al3+ and phosphate groups in phytic acid molecules. The conformation models of the deposition film are proposed.

  6. Improvement of the wear resistance of electroplated Au-Ni coatings by Zr ion bombardment of Ni-B sublayer

    SciTech Connect

    Lyazgin, Alexander Shugurov, Artur Sergeev, Viktor Neufeld, Vasily; Panin, Alexey; Shesterikov, Evgeny

    2015-10-27

    The effect of bombardment of the Ni-B sublayer by Zr ion beams on the surface morphology and tribomechanical properties of Au-Ni coatings was investigated. It was found that the treatment has no significant effect on the surface roughness and grain size of the Au-Ni coatings, while it provides essential reducing of their friction coefficient and improvement of wear resistance. It is shown that increased wear resistance of these coatings was caused by their strain hardening resulted from localization of plastic strain. The optimal Zr fluence were determined that provide the maximum reduction of linear wear of the coatings.

  7. The study of crack resistance of TiAlN coatings under mechanical loading and thermal cycle testing

    SciTech Connect

    Akulinkin, Alexandr Shugurov, Artur Sergeev, Viktor; Panin, Alexey; Cheng, C.-H.

    2015-10-27

    The effect of preliminary ion bombardment of 321 stainless steel substrate on crack resistance of TiAlN coatings at uniaxial tension and thermal cycling is studied. The ion-beam treatment of the substrate is shown to substantially improve the adhesion strength of the coatings that prevents their delamination and spalling under uniaxial tension. The resistance to crack propagation and spalling by the thermal shock is higher in the TiAlN coating deposited onto the substrate subjected to Ti ion bombardment as compared to that in the TiAlN coating deposited onto the initial substrate.

  8. Thermally resistant polymers for fuel tank sealants

    NASA Technical Reports Server (NTRS)

    Webster, J. A.

    1972-01-01

    Conversion of fluorocarbon dicarboxylic acid to intermediates whose terminal functional groups permit polymerization is discussed. Resulting polymers are used as fuel tank sealers for jet fuels at elevated temperatures. Stability and fuel resistance of the prototype polymers is explained.

  9. A preliminary petrogenetic grid for REE fluorocarbonates and associated minerals

    NASA Astrophysics Data System (ADS)

    Williams-Jones, Anthony E.; Wood, Scott A.

    1992-02-01

    The bulk of the world's economic LREE reserves occur as fluorocarbonate minerals, notably bastnaesite. However, despite the importance of these minerals, very little is known about the physicochemical conditions controlling their formation. In this paper we attempt to partly redress this deficiency by qualitatively determining P- T and compositional relationships for part of the system Ln(CO 3)F-CaCO 3-F 2(CO 3) -1-H 2O, including the minerals fluorite, calcite, bastnaesite, parisite, synchysite and fluocerite. This degenerate ( n + 3)-phase multisystem has 23 possible base P- T topologies, plus their mirror images and trivial conjugates, from which we have been able to select a single probable stable topology using a combination of published experimental phase equilibrium data, molar volume and entropy estimates and natural assemblage data. Compositional relationships in the system have been established by constructing log ( aca2+ · aF-2) vs. log ( a F -2/a CO 32-) diagrams for each of the stable divariant regions shown on the P- T net. Important conclusions of the study with respect to P- T relationships are (1) that all of the above REE-fluorocarbonate minerals can form at comparatively low pressure and temperature; (2) that bastnaesite + fluorite is a low-temperature assemblage and, in the presence of synchysite or calcite, is also restricted to low or high pressure, respectively; (3) that parisite + fluorite is stable to higher temperatures; (4) that bastnaesite + synchysite + calcite is restricted to high P- T conditions; (5) that parisite reacts to form bastnaesite and calcite at high temperatures (<620°C at 1 kb); and (6) that bastnaesite-(La) decomposes by a decarbonation reaction at temperatures <750°C at 1 kb and at lower temperatures with decreasing ionic radius of the lanthanide. The principal conclusions with respect to compositional relationships are (1) that transformations among the REE fluorocarbonates cannot occur through changes in F

  10. Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems

    SciTech Connect

    Gopala N. Krishnan; Ripudaman Malhotra; Jordi Perez; Marc Hornbostel; Kai-Hung Lau; Angel Sanjurjo

    2007-05-31

    Advanced electric power generation systems use a coal gasifier to convert coal to a gas rich in fuels such as H{sub 2} and CO. The gas stream contains impurities such as H{sub 2}S and HCl, which attack metal components of the coal gas train, causing plant downtime and increasing the cost of power generation. Corrosion-resistant coatings would improve plant availability and decrease maintenance costs, thus allowing the environmentally superior integrated-gasification-combined-cycle (IGCC) plants to be more competitive with standard power-generation technologies. Heat-exchangers, particle filters, turbines, and other components in the IGCC system must withstand the highly sulfiding conditions of the high-temperature coal gas over an extended period of time. The performance of components degrades significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low cost alloy will improve is resistance to such sulfidation attack and decrease capital and operating costs. The alloys used in the gasifier service include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive nickel-cobalt alloys. The Fe- and Ni-based high-temperature alloys are susceptible to sulfidation attack unless they are fortified with high levels of Cr, Al, and Si. To impart corrosion resistance, these elements need not be in the bulk of the alloy and need only be present at the surface layers. In this study, the use of corrosion-resistant coatings on low alloy steels was investigated for use as high-temperature components in IGCC systems. The coatings were deposited using SRI's fluidized-bed reactor chemical vapor deposition technique. Diffusion coatings of Cr and Al were deposited by this method on to dense and porous, low alloy stainless steel substrates. Bench-scale exposure tests at 900 C with a simulated coal gas stream containing 1.7% H{sub 2}S showed that the low alloy steels such SS405 and SS409 coated with {approx

  11. Improvement of corrosion resistance of transparent conductive multilayer coating consisting of silver layers and transparent metal oxide layers

    SciTech Connect

    Koike, Katsuhiko; Yamazaki, Fumiharu; Okamura, Tomoyuki; Fukuda, Shin

    2007-05-15

    An optical filter for plasma display panel (PDP) requires an electromagnetic shield with very high ability. The authors investigated a transparent conductive multilayer coating consisting of silver (Ag) layers and transparent metal oxide layers. The durability of the multilayer sputter coating, including the silver layer, is very sensitive to the surrounding atmosphere. For example, after an exposure test they found discolored points on the multilayer sputter coatings, possibly caused by migration of silver atoms in the silver layers. In their investigation, they modified the top surface of the multilayer sputter coatings with transition metals to improve the corrosion resistance of the multilayer coating. Specifically, they deposited transition metals 0.5-2 nm thick on the top surface of the multilayer coatings by sputtering. They chose indium tin oxide (ITO) as the transparent metal oxide. They applied the multilayer sputter coatings of seven layers to a polyethylene terephthalate (PET) film substrate. A cross-sectional structure of the film with the multilayer coatings is PET film/ITO/Ag/ITO/Ag/ITO/Ag/ITO. They evaluated the corrosion resistance of the films by a salt-water immersion test. In the test, they immersed the film with multilayer coatings into salt water, and then evaluated the appearance, transmittance, and electrical resistance of the multilayer coatings. They investigated several transition metals as the modifying material, and found that titanium and tantalum drastically improved the resistance of the multilayer coatings to the salt-water exposure without a significant decline in transmittance. They also investigated the relation between elapsed time after deposition of the modifying materials and resistance to the salt water. Furthermore, they investigated the effects of a heat treatment and an oxide plasma treatment on resistance to the salt water.

  12. Advanced fluorocarbon-based systems for oxygen and drug delivery, and diagnosis.

    PubMed

    Riess, J G; Krafft, M P

    1997-01-01

    Fluorocarbons and fluorocarbon-derived materials constitute a vast family of synthetic components that have a range of remarkable properties including exceptional chemical and biological inertness, gas-dissolving capacity, low surface tension, high fluidity, excellent spreading characteristics, unique hydro- and lipophobicity, high density, absence of protons, and magnetic susceptibility close to that of water. These properties lead to a diversity of products and applications as illustrated by those products that are already in advanced clinical trials, which comprise: 1) an injectable oxygen carrier, i.e. blood substitute, consisting of a fluorocarbon-in-water emulsion for use in surgery to alleviate the problems raised by the transfusion of homologous blood; the same emulsion is also being evaluated with cardiopulmonary bypass patients; 2) a neat fluorocarbon for treatment of acute respiratory failure by liquid ventilation; and 3) fluorocarbon-based or stabilized gas bubbles to be used as contrast agents for the assessment of heart function and detection of perfusion defects by ultrasound imaging. Proper selection of the fluorocarbon best suited for the intended application, formulation optimization, and advanced stabilization and processing procedures led to effective, ready-for-use products with minimal side-effects. Further highly fluorinated materials, including amphiphiles and various fluorocarbon-based colloidal systems that have potential as pulmonary, topical and ophthalmological drug delivery agents, and as skin protection barriers, are now being investigated. Such systems include drug-in-fluorocarbon suspensions, reverse water-in-fluorocarbon emulsions, oil-in-fluorocarbon emulsions, multiple emulsions, microemulsions, fluorocarbon gels, fluorinated liposomes, fluorinated tubules and other novel supramolecular systems.

  13. The Microstructure and Wear Resistance of Microarc Oxidation Composite Coatings Containing Nano-Hexagonal Boron Nitride (HBN) Particles

    NASA Astrophysics Data System (ADS)

    Li, Zhenwei; Di, Shichun

    2017-03-01

    The composite coatings containing HBN were prepared on 2024 aluminum alloy by microarc oxidation in the electrolyte with nano-HBN particles. The microstructure, surface roughness, phase composition, hardness, adhesion strength and wear resistance of composite coatings were analyzed by SEM, EDS, laser confocal microscope, XRD, Vickers hardness tester, scratch test and ball-on-disc abrasive tests. The results revealed that composite coatings were mainly composed of γ-Al2O3, α-Al2O3, mullite and HBN. With increasing the content of HBN particles in the electrolyte, the size and number of the pores on the surface of composite coatings decreased significantly. Compared to the MAO coatings without HBN, the composite coatings exhibited better wear resistance, as demonstrated by the lower friction coefficient and the lower wear rate.

  14. Corrosion resistance of biodegradable polymeric layer-by-layer coatings on magnesium alloy AZ31

    NASA Astrophysics Data System (ADS)

    Cui, Lan-Yue; Zeng, Rong-Chang; Zhu, Xiao-Xiao; Pang, Ting-Ting; Li, Shuo-Qi; Zhang, Fen

    2016-06-01

    Biocompatible polyelectrolyte multilayers (PEMs) and polysiloxane hybrid coatings were prepared to improve the corrosion resistance of biodegradable Mg alloy AZ31. The PEMs, which contained alternating poly(sodium 4-styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH), were first self-assembled on the surface of the AZ31 alloy substrate via electrostatic interactions, designated as (PAH/PSS)5/AZ31. Then, the (PAH/PSS)5/AZ31 samples were dipped into a methyltrimethoxysilane (MTMS) solution to fabricate the PMTMS films, designated as PMTMS/(PAH/PSS)5/AZ31. The surface morphologies, microstructures and chemical compositions of the films were investigated by FE-SEM, FTIR, XRD and XPS. Potentiodynamic polarization, electrochemical impedance spectroscopy and hydrogen evolution measurements demonstrated that the PMTMS/(PAH/PSS)5/AZ31 composite film significantly enhanced the corrosion resistance of the AZ31 alloy in Hank's balanced salt solution (HBSS). The PAH and PSS films effectively improved the deposition of Ca-P compounds including Ca3(PO4)2 and hydroxyapatite (HA). Moreover, the corrosion mechanism of the composite coating was discussed. These coatings could be an alternative candidate coating for biodegradable Mg alloys.

  15. Influence of Processing and Heat Treatment on Corrosion Resistance and Properties of High Alloyed Steel Coatings

    NASA Astrophysics Data System (ADS)

    Hill, Horst; Weber, Sebastian; Raab, Ulrich; Theisen, Werner; Wagner, Lothar

    2012-09-01

    Corrosion and abrasive wear are two important aspects to be considered in numerous engineering applications. Looking at steels, high-chromium high-carbon tool steels are proper and cost-efficient materials. They can either be put into service as bulk materials or used as comparatively thin coatings to protect lower alloyed construction or heat treatable steels from wear and corrosion. In this study, two different corrosion resistant tool steels were used for the production of coatings and bulk material. They were processed by thermal spraying and super solidus liquid phase sintering as both processes can generally be applied to produce coatings on low alloyed substrates. Thermally sprayed (high velocity oxygen fuel) coatings were investigated in the as-processed state, which is the most commonly used condition for technical applications, and after a quenching and tempering treatment. In comparison, sintered steels were analyzed in the quenched and tempered condition only. Significant influence of alloy chemistry, processing route, and heat treatment on tribological properties was found. Experimental investigations were supported by computational thermodynamics aiming at an improvement of tribological and corrosive resistance.

  16. Acrylic coatings exhibiting improved hardness, solvent resistance and glossiness by using silica nano-composites

    NASA Astrophysics Data System (ADS)

    Dashtizadeh, Ahmad; Abdouss, Majid; Mahdavi, Hossein; Khorassani, Manuchehr

    2011-01-01

    To prepare nano-composite emulsion acrylic resins with improved surface hardness and solvent resistance, nano-silica particles were treated with surfactants. The monomers of methyl methacrylate/butylacrylate were co-polymerized on the surface of dispersed silica particles. Several emulsions with different silica contents and copolymer mole fractions were prepared. Finally the emulsions were modified to water-based acrylic coatings and improved properties such as surface hardness, solvent resistance and glossiness were determined. The study of coatings was directed to find the improved resin by optimum surface properties. Size distribution and morphology of latexes were characterized by Fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy and scanning electron microscopy. The glass transition temperature of nano-composites was measured and discussed its relation with silica contents, monomer mole fractions and improved properties of coatings. The optimum pendulum hardness of coatings was on 0.46 methyl methacrylate mole fraction and 120 g silica content. An increase in pendulum hardness of nano-composites with the addition of modified silica was observed. DLS and TEM studies indicate that silica particles were dispersed homogenously through the polymer matrix.

  17. Evaluation of atomic oxygen resistant protective coatings for fiberglass-epoxy composites in LEO

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Paulsen, Phillip E.; Brady, Joyce A.

    1989-01-01

    Fiberglass-epoxy composite masts are the prime structural members for the Space Station Freedom solar array. At the altitude where Space Station Freedom will operate, atomic oxygen atoms are the most predominant species. Atomic oxygen is highly reactive and has been shown to oxidize organic and some metallic materials. Tests with random and directed atomic oxygen exposure have shown that the epoxy is removed from the composite exposing brittle glass fibers which could be easily removed from the surface where they could contaminate Space Station Freedom Systems. Protection or fiber containment systems; inorganic based paints, aluminum braid, and a metal coating; were evaluated for resistance to atomic oxygen, vacuum ultraviolet radiation, thermal cycling, and mechanical flexing. All appeared to protect well against atomic oxygen and provide fiber containment except for the single aluminum braid covering. UV radiation resistance was acceptable and in general, thermal cycling and flexure had little to no effect on the mass loss rate for most coatings.

  18. Electrostatic coating enhances bioavailability of insecticides and breaks pyrethroid resistance in mosquitoes

    PubMed Central

    Andriessen, Rob; Snetselaar, Janneke; Suer, Remco A.; Osinga, Anne J.; Deschietere, Johan; Lyimo, Issa N.; Mnyone, Ladslaus L.; Brooke, Basil D.; Ranson, Hilary; Knols, Bart G. J.; Farenhorst, Marit

    2015-01-01

    Insecticide resistance poses a significant and increasing threat to the control of malaria and other mosquito-borne diseases. We present a novel method of insecticide application based on netting treated with an electrostatic coating that binds insecticidal particles through polarity. Electrostatic netting can hold small amounts of insecticides effectively and results in enhanced bioavailability upon contact by the insect. Six pyrethroid-resistant Anopheles mosquito strains from across Africa were exposed to similar concentrations of deltamethrin on electrostatic netting or a standard long-lasting deltamethrin-coated bednet (PermaNet 2.0). Standard WHO exposure bioassays showed that electrostatic netting induced significantly higher mortality rates than the PermaNet, thereby effectively breaking mosquito resistance. Electrostatic netting also induced high mortality in resistant mosquito strains when a 15-fold lower dose of deltamethrin was applied and when the exposure time was reduced to only 5 s. Because different types of particles adhere to electrostatic netting, it is also possible to apply nonpyrethroid insecticides. Three insecticide classes were effective against strains of Aedes and Culex mosquitoes, demonstrating that electrostatic netting can be used to deploy a wide range of active insecticides against all major groups of disease-transmitting mosquitoes. Promising applications include the use of electrostatic coating on walls or eave curtains and in trapping/contamination devices. We conclude that application of electrostatically adhered particles boosts the efficacy of WHO-recommended insecticides even against resistant mosquitoes. This innovative technique has potential to support the use of unconventional insecticide classes or combinations thereof, potentially offering a significant step forward in managing insecticide resistance in vector-control operations. PMID:26324912

  19. Enhanced high temperature oxidization resistance of silica coated γ-Ce2S3 red pigments

    NASA Astrophysics Data System (ADS)

    Liu, Shun-Guo; Li, Yue-Ming; Wang, Zhu-Mei; Shen, Zong-Yang; Xie, Zhi-Xiang

    2016-11-01

    Silica layer coated γ-Ce2S3 red pigments were successfully prepared based on a Stober method followed by a hydrogen-argon atmosphere heat treatment at 700 °C. The effect of water/ethanol volume ratio and tetraethoxysilane concentration on the microstructure of the coating layer and its high temperature oxidizing protection to pigments was investigated. A transparent silica coating layer with dense microstructure and about 60 nm thickness can provide a favorable protection for the red hue of the γ-Ce2S3 pigments. The oxidization resistant temperature was enhanced to 550 °C for the dense silica layer coated γ-Ce2S3 pigments as compared to ≤350 °C for the uncoated ones. A red color (L* = 29.59, a* = 27.53 and b* = 27.66) was still remained for such silica coated γ-Ce2S3 pigments after heated treated at 550 °C in air, indicating its potential for high temperature industrial applications.

  20. Biocompatibility of corrosion-resistant zeolite coatings for titanium alloy biomedical implants.

    PubMed

    Bedi, Rajwant S; Beving, Derek E; Zanello, Laura P; Yan, Yushan

    2009-10-01

    Titanium alloy, Ti6Al4V, is widely used in dental and orthopedic implants. Despite its excellent biocompatibility, Ti6Al4V releases toxic Al and V ions into the surrounding tissue after implantation. In addition, the elastic modulus of Ti6Al4V ( approximately 110GPa) is significantly higher than that of bone (10-40GPa), leading to a modulus mismatch and consequently implant loosening and deosteointegration. Zeolite coatings are proposed to prevent the release of the toxic ions into human tissue and enhance osteointegration by matching the mechanical properties of bone. Zeolite MFI coatings are successfully synthesized on commercially pure titanium and Ti6Al4V for the first time. The coating shows excellent adhesion by incorporating titanium from the substrate within the zeolite framework. Higher corrosion resistance than the bare titanium alloy is observed in 0.856M NaCl solution at pHs of 7.0 and 1.0. Zeolite coatings eliminate the release of cytotoxic Al and V ions over a 7 day period. Pluripotent mouse embryonic stem cells show higher adhesion and cell proliferation on the three-dimensional zeolite microstructure surface compared with a two-dimensional glass surface, indicating that the zeolite coatings are highly biocompatible.

  1. Development of HVOF Sprayed Erosion/Oxidation Resistant Coatings for Composite Structural Components in Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Knight, R.; Ivosevic, M.; Twardowski, T. E.; Kalidindi, S. R.; Sutter, James K.; Kim, D. Y.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Thermally sprayed coatings are being studied and developed as methods of enabling lightweight composites to be used more extensively as structural components in propulsion applications in order to reduce costs and improve efficiency through weight reductions. The primary goal of this work is the development of functionally graded material [FGM] polymer/metal matrix composite coatings to provide improved erosion/oxidation resistance to polyimide-based polymer matrix composite [PMC] substrates. The goal is to grade the coating composition from pure polyimide, similar to the PMC substrate matrix on one side, to 100 % WC-Co on the other. Both step-wise and continuous gradation of the loading of the WC-Co reinforcing phase are being investigated. Details of the coating parameter development will be presented, specifically the high velocity oxy-fuel [HVOF] combustion spraying of pure PMR-11 matrix material and layers of various composition PMR-II/WC-Co blends onto steel and PMR-15 composite substrates. Results of the HVOF process optimization, microstructural characterization, and analysis will be presented. The sprayed coatings were evaluated using standard metallographic techniques - optical and scanning electron microscopy [SEM]. An SEM + electron dispersive spectroscopy [EDS] technique has also been used to confirm retention of the PMR-II component. Results of peel/butt adhesion testing to determine adhesion will also be presented.

  2. Development of HVOF Sprayed Erosion/Oxidation Resistant Coatings for Composite Structural Components in Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Ivosevic, M.; Twardowski, T.; Kalidindi, S.; Knight, R.; Sutter, J.; Kim, D. Y.

    1990-01-01

    Thermally sprayed coatings are being studied and developed as methods of enabling lightweight composites to be used more extensively as structural components in propulsion applications in order to reduce costs and improve efficiency through weight reductions. The primary goal of this work is the development of functionally graded material [FGM] polymer/metal matrix composite coatings to provide improved erosion/oxidation resistance to polyimide-based polymer matrix composite [PMC] substrates. The goal is to grade the coating composition from pure polyimide, similar to the PMC substrate matrix on one side, to 100% WC-Co on the other. Both step-wise and continuous gradation of the loading of the WC-Co reinforcing phase are being investigated, Details of the coating parameter development will be presented, specifically the high velocity oxy-fuel [HVOF] combustion spraying of pure PMR-I1 matrix material and layers of various composition PMR-II/WC-Co blends onto steel and PMR-15 composite substrates. Results of the HVOF process optimization, microstructural characterization, and analysis will be presented. The sprayed coatings were evaluated using standard metallographic techniques - optical and scanning electron microscopy [SEMI. An SEM + electron dispersive spectroscopy [EDS] technique has also been used to confirm retention of the PMR-I1 component. Results of peel/butt adhesion testing to determine adhesion will also be presented.

  3. Graphene coating makes carbon nanotube aerogels superelastic and resistant to fatigue

    NASA Astrophysics Data System (ADS)

    Kim, Kyu Hun; Oh, Youngseok; Islam, M. F.

    2012-09-01

    Lightweight materials that are both highly compressible and resilient under large cyclic strains can be used in a variety of applications. Carbon nanotubes offer a combination of elasticity, mechanical resilience and low density, and these properties have been exploited in nanotube-based foams and aerogels. However, all nanotube-based foams and aerogels developed so far undergo structural collapse or significant plastic deformation with a reduction in compressive strength when they are subjected to cyclic strain. Here, we show that an inelastic aerogel made of single-walled carbon nanotubes can be transformed into a superelastic material by coating it with between one and five layers of graphene nanoplates. The graphene-coated aerogel exhibits no change in mechanical properties after more than 1 × 106 compressive cycles, and its original shape can be recovered quickly after compression release. Moreover, the coating does not affect the structural integrity of the nanotubes or the compressibility and porosity of the nanotube network. The coating also increases Young's modulus and energy storage modulus by a factor of ~6, and the loss modulus by a factor of ~3. We attribute the superelasticity and complete fatigue resistance to the graphene coating strengthening the existing crosslinking points or `nodes' in the aerogel.

  4. Increasing wear resistance of copper friction pair with electrically-conductive tribological Cu-Mo-S coatings

    NASA Astrophysics Data System (ADS)

    Zharkov, S. Yu.; Sergeev, V. P.; Fedorischeva, M. V.; Sergeev, O. V.; Kalashnikov, M. P.

    2016-11-01

    The composite solid lubricant Cu-Mo-S coating was produced by pulse magnetron sputtering system. The electrical resistivity of deposited Cu-Mo-S coatings was (22.8±3) × 10-8 Ohm×m. Cu-Mo-S coatings decrease the wear rate of the copper friction pair by 38 times. The decrease in the wear rate occurs owing to the formation of a transferred film on the counterface.

  5. Corrosion resistance of Ti-Ta-Zr coatings in the Boiling Acid Solutions

    NASA Astrophysics Data System (ADS)

    Polyakov, I. A.; Lenivtseva, O. G.; Samoylenko, V. V.; Colkovski, M. G.; Ivanchik, I. S.

    2016-11-01

    In this study corrosion resistance of Ti-Ta-Zr coatings fabricated on VT14 titanium alloy workpieces using a high-energy electron beam injected in the atmosphere was investigated. Estimation of corrosion resistance of surface alloyed layers was carried out by the weight-change method. Boiling solution of 65 % nitric acid in water and 5 % of sulfuric acid in water were used as the corrosive environments. Investigation of samples after corrosion tests was carried out using a Carl Zeiss EVO 50 XVP scanning electron microscope.

  6. Laser damage resistant pits in dielectric coatings created by femtosecond laser machining

    SciTech Connect

    Wolfe, J; Roger Qiu, ,; Stolz, C; Thomas, M; Martinez, C; Ozkan, A

    2009-11-03

    Replacing growing damage sites with benign, laser damage resistant features in multilayer dielectric films may enable large mirrors to be operated at significantly higher fluences. Laser damage resistant features have been created in high reflecting coatings on glass substrates using femtosecond laser machining. These prototype features have been damage tested to over 40 J/cm{sup 2} (1064nm, 3ns pulselength) and have been shown not to damage upon repeated irradiation at 40J/cm{sup 2}. Further work to optimize feature shape and laser machining parameters is ongoing.

  7. Effects of coating roughness and biofouling on ship resistance and powering.

    PubMed

    Schultz, Michael P

    2007-01-01

    Predictions of full-scale ship resistance and powering are made for antifouling coating systems with a range of roughness and fouling conditions. The estimates are based on results from laboratory-scale drag measurements and boundary layer similarity law analysis. In the present work, predictions are made for a mid-sized naval surface combatant at cruising speed and near maximum speed. The results indicate that slime films can lead to significant increases in resistance and powering, and heavy calcareous fouling results in powering penalties up to 86% at cruising speed. The present estimates show good agreement with results from full-scale ship power trials.

  8. Oxidation resistance of Al2O3-nanostructured/CSZ composite compared to conventional CSZ and YSZ thermal barrier coatings

    NASA Astrophysics Data System (ADS)

    Keyvani, A.; Bahamirian, M.

    2016-10-01

    Thermal barrier coatings are widely used in combustion sections of turbine engines, however, their main disadvantage is the spallation from the bond coat, occurring due to oxidation and formation of thermally grown oxide (TGO). In this paper, the oxidation resistance of yttria stabilized zirconia (YSZ), ceria stabilized zirconia (CSZ), and Al2O3-nanostructured/CSZ composite coatings have been studied and compared with each other. Samples were heated in air at 1100 °C using an electrical furnace. Three types of the top coats were applied by thermal spray technique on IN738LC base metal. Scanning electron microscopy was used to study the microstructure of the coatings before and after the oxidation. The experimental results showed that Al2O3-nanostructured/CSZ composite coating exhibits considerably better oxidation resistance compared to conventional YSZ and CSZ coatings. The microstructural analysis indicated a smaller growth of TGO in the Al2O3-nanostructured/CSZ composite coating, improving the oxidation resistance of the coating.

  9. Process for producing a well-adhered durable optical coating on an optical plastic substrate. [abrasion resistant polymethyl methacrylate lenses

    NASA Technical Reports Server (NTRS)

    Kubacki, R. M. (Inventor)

    1978-01-01

    A low temperature plasma polymerization process is described for applying an optical plastic substrate, such as a polymethyl methacrylate lens, with a single layer abrasive resistant coating to improve the durability of the plastic.

  10. Robust Ultralow-k Dielectric (Fluorocarbon) Deposition by Microwave Plasma-Enhanced Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Kikuchi, Yoshiyuki; Miyatani, Kotaro; Kobayashi, Yasuo; Kawamura, Kohei; Nemoto, Takenao; Nakamura, Masahiro; Matsumoto, Hirokazu; Ito, Azumi; Shirotori, Akihide; Nozawa, Toshihisa; Matsuoka, Takaaki

    2012-05-01

    A robust fluorocarbon film was successfully deposited on a substrate at a temperature above 400 °C by the new microwave plasma-enhanced chemical vapor deposition (MWPE-CVD) method using the linear C5F8 precursor instead of a conventional cyclic C5F8 one. The fluorocarbon performed keeping the dielectric constant low as a value of 2.25 by controlling the molecular structure forming cross-linked poly(tetrafluoroethylene) (PTFE) chains with configurational carbon atoms. The novel fluorocarbon demonstrates less fluorine degassing at an elevated temperature, with high mechanical strength and without degradation of adhesion of the fluorocarbon film to SiCN and SiOx stacked films after thermal stress at 400 °C and 1 atm N2 for 1 h. Consequently, this robust fluorocarbon film is considered a promising candidate for general porous silicon materials with applications to practical integration processes as an interlayer dielectric.

  11. Preparation and Testing of Corrosion and Spallation-Resistant Coatings

    SciTech Connect

    Hurley, John

    2015-11-01

    This Energy & Environmental Research Center (EERC) project is designed to determine if plating APMT®, a specific highly oxidation-resistant oxide dispersion-strengthened FeCrAl alloy made by Kanthal, onto nickel-based superalloy turbine parts is a viable method for substantially improving the lifetimes and maximum use temperatures of the parts. The method for joining the APMT plate to the superalloys is called evaporative metal bonding and involves placing a thin foil of zinc between the plate and the superalloy, clamping them together, and heating in an atmosphere-controlled furnace. Upon heating, the zinc melts and dissolves the oxide skins of the alloys at the bond line, allowing the two alloys to diffuse into each other. The zinc then diffuses through the alloys and evaporates from their surfaces. During this annual reporting period, the finite element model was completed and used to design clamping jigs to hold the APMT plate to the larger blocks of superalloys during the bonding process. The clamping system was machined from titanium–zirconium–molybdenum and used to bond the APMT plate to the superalloy blocks. The bond between the APMT plate was weak for one of each of the superalloy blocks. We believe that this occurred because enough oxidation had occurred on the surface of the parts as a result of a 1-month time period between sandblasting to prepare the parts and the actual bonding process. The other blocks were, therefore, bonded within 1 day of preparing the parts for bonding, and their joints appear strong. Scanning electron microscopy analyses of representative joints showed that no zinc remained in the alloys after bonding. Also, phases rich in hafnium and tantalum had precipitated near the bond line in the APMT. Iron from the APMT had diffused into the superalloys during bonding, more extensively in the CM247LC than in the Rene 80. Nickel from the superalloys had diffused into the APMT, again more extensively in the joint with the CM247LC than

  12. A Study on Wear Resistance of HVOF-Sprayed Ni-MoS2 Self-Lubricating Composite Coatings

    NASA Astrophysics Data System (ADS)

    Liu, Y. L.; Jeng, M. C.; Hwang, J. R.; Chang, C. H.

    2015-02-01

    Composite coating techniques are becoming increasingly popular owing to their peculiar performances. In this study, the wear resistance of thermally sprayed Ni-MoS2 composite coatings on an AISI 1020 steel substrate was investigated. Ni-MoS2 composite powder (size: 60-90 μm) containing 25 wt.% of dispersed MoS2 was prepared by electroless plating. Ni-MoS2 composite coatings were then prepared by HVOF thermal spraying. The coatings were characterized by structural, surface morphological, and compositional analyses by means of microhardness tests, SEM/EDS, XRD, and ICP-AES. For the evaluation of their anti-wear properties, the composites were subjected to ball-on-disk dry wear tests based on the ASTM G99 standard at room temperature. Experimental results showed that some of the MoS2 content dispersed in the Ni-based composite coating burnt away during the high-temperature spraying process, thereby reducing the MoS2 concentration in the coating. In the wear test, the weight loss in the Ni-MoS2 composite coating was minimal under a low load (<15 N) but increased rapidly with increasing load (>30 N). The average wear rate of the coatings was found to be ~1/40 times that of a Ni coating, showing that the wear resistance of the composite coatings was significantly improved by MoS2 addition.

  13. Preparation and testing of corrosion and spallation-resistant coatings

    SciTech Connect

    Hurley, John

    2012-09-30

    This Energy & Environmental Research Center (EERC) project is designed to determine if plating APMT, a specific highly oxidation-resistant oxide dispersion-strengthened FeCrAl alloy made by Kanthal, onto nickel-based superalloy turbine parts is a viable method for substantially improving the lifetimes and maximum use temperatures of the parts. The method for joining the APMT plate to the superalloys is called evaporative metal bonding. It involves placing a thin foil of zinc (Zn) between the plate and the superalloy, clamping them together, and heating in an atmosphere-controlled furnace. Upon heating, the Zn melts and dissolves the oxide skins of the alloys at the bond line, allowing the two alloys to diffuse into each other. The Zn then diffuses through the alloys and evaporates from their surfaces. Laboratory testing has shown that the diffusion rate of Zn through the FeCrAl alloy is much faster than through the nickel superalloys. This means that the FeCrAl will serve as a sink for the Zn bonding alloy during the evaporative metal bonding process. Also, the testing has shown that the Zn diffusion mechanism is bulk diffusion, and not intergranular. This is a surprise. However, it means that quantification of the Zn diffusivities in these samples will be significantly simpler than would have been the case if grain boundary diffusion dominated. In addition to the laboratory testing, gas impinger and particulate samples are being collected from a combustor firing syngas and natural gas to determine what types of microcontaminants may reach a turbine firing syngas. The syngas is created in one of two different pilot-scale pressurized coal gasifiers. The initial analysis of the impinger solutions was for standard U.S. Environmental Protection Agency (EPA) Method 29 determination of hazardous metals and did not include major element analysis. When syngas is fired, the amount of Mn in the combustor gas increases substantially. Halogens (Br2 and Cl2) and hydrogen

  14. Preparation and testing of corrosion and spallation-resistant coatings

    SciTech Connect

    Hurley, John P.; Cavalli, Matthew N.

    2016-06-30

    The goal of this project was to take a recently developed method of bonding oxide dispersion-strengthened (ODS) FeCrAl plating to nickel superalloys closer to commercial use in syngas-fired turbines. The project was designed to better understand and develop the bonding process and to determine if plating APMT®, a specific highly oxidation-resistant ODS FeCrAl alloy made by Kanthal, onto nickel-based superalloy turbine parts is a viable method for substantially improving the lifetimes and maximum use temperatures of the parts. The superalloys investigated for protection were CM247LC and Rene® 80, both alumina scale-forming alloys. The method for bonding the APMT plate to the superalloys is called evaporative metal bonding, which involves placing a thin foil of zinc between the plate and the superalloy, clamping them together, and heating in an atmosphere-controlled furnace. Upon heating, the zinc melts and dissolves the oxide skins of the alloys at the bond line, allowing the two alloys to diffuse into each other. The zinc then diffuses through the alloys and evaporates from their surfaces, creating a bond between the APMT and the superalloy that is stronger than the APMT itself. Testing showed that the diffusivity of zinc in both APMT and CM247LC is quite similar at 700°C but 15 times higher in the APMT at 1214°C. Coefficients of thermal expansion were determined for each of the alloys as a function of temperature. This information was entered into a finite-element model using ANSYS, which was used to design a clamping jig for pressing the APMT to the superalloys at the bonding temperature. Scanning electron microscopy analyses of representative joints showed that no zinc remained in the alloys after bonding Unfortunately, the analyses also showed some small pieces of broken aluminum oxide scale near the bond lines, indicating that its scale was not sufficiently removed during prebonding cleaning. Samples from each of the bonded blocks were sent to Siemens for

  15. Enhancement of seawater corrosion resistance in copper using acetone-derived graphene coating

    NASA Astrophysics Data System (ADS)

    Huh, Jae-Hoon; Kim, Seung Hyun; Chu, Jae Hwan; Kim, Sung Youb; Kim, Ji Hyun; Kwon, Soon-Yong

    2014-03-01

    We show that acetone-derived graphene coating can effectively enhance the corrosion efficiency of copper (Cu) in a seawater environment (0.5-0.6 M (~3.0-3.5%) sodium chloride). By applying a drop of acetone (~20 μl cm-2) on Cu surfaces, rapid thermal annealing allows the facile and rapid synthesis of graphene films on Cu surfaces with a monolayer coverage of almost close to ~100%. Under optimal growth conditions, acetone-derived graphene is found to have a relatively high crystallinity, comparable to common graphene grown by chemical vapor deposition. The resulting graphene-coated Cu surface exhibits 37.5 times higher corrosion resistance as compared to that of mechanically polished Cu. Further, investigation on the role of graphene coating on Cu surfaces suggests that the outstanding corrosion inhibition efficiency (IE) of 97.4% is obtained by protecting the underlying Cu against the penetration of both dissolved oxygen and chlorine ions, thanks to the closely spaced atomic structure of the graphene sheets. The increase of graphene coating thickness results in the enhancement of the overall corrosion IE up to ~99%, which can be attributed to the effective blocking of the ionic diffusion process via grain boundaries. Overall, our results suggest that the acetone-derived graphene film can effectively serve as a corrosion-inhibiting coating in the seawater level and that it may have a promising role to play for potential offshore coating.We show that acetone-derived graphene coating can effectively enhance the corrosion efficiency of copper (Cu) in a seawater environment (0.5-0.6 M (~3.0-3.5%) sodium chloride). By applying a drop of acetone (~20 μl cm-2) on Cu surfaces, rapid thermal annealing allows the facile and rapid synthesis of graphene films on Cu surfaces with a monolayer coverage of almost close to ~100%. Under optimal growth conditions, acetone-derived graphene is found to have a relatively high crystallinity, comparable to common graphene grown by

  16. Oxidation-resistant coating for gamma titanium aluminides by pack cementation

    SciTech Connect

    Mabuchi, H.; Tsuda, H.; Kawakami, T.; Nakamatsu, S.; Matsui, T.; Morii, K.

    1999-08-06

    Gamma titanium aluminides ({gamma}-TiAl alloys), having an L1{sub 0}-type structure, are candidate materials for use in future gas turbine aero-engines and automotive engines because of their low density, high specific strength and high stiffness. In air, however, it is well known that titanium aluminide oxidizes at a more rapid rate at temperatures above 1,123 K; therefore, the oxidation resistance becomes a critical factor for TiAl alloys to be used at high temperatures (perhaps above 1,073 K). Coatings for the TiAl alloy are essential to high temperature oxidation resistance. The Al-Ti-Cr ternary phase diagram at 1,423 K indicates that the L1{sub 2} phase field is in equilibrium with the TiAl(L1{sub 0}) phase field. Furthermore, the L1{sub 0}- and L1{sub 2}-alloys in this ternary system resemble each other very closely in crystal structure and lattice parameter (TiAl(L1{sub 0}); a = 0.4005, c = 0.4070 nm (27), Ti-67Al-8Cr(L1{sub 2}); a = 0.3960nm (25)). Therefore, the L1{sub 2}-(Al,Cr){sub 3}Ti alloy can be considered applicable to L1{sub 0}-TiAl alloys as an optimum material for coatings. The purpose of this study is to apply L1{sub 2} alloy coatings to the TiAl alloys by pack cementation techniques, and to evaluate the oxidation resistance of the coated alloys.

  17. PREPARATION AND TESTING OF CORROSIONAND SPALLATION-RESISTANT COATINGS

    SciTech Connect

    Hurley, John

    2014-11-01

    This Energy & Environmental Research Center (EERC) project is designed to determine if plating APMT®, a specific highly oxidation-resistant oxide dispersion-strengthened FeCrAl alloy made by Kanthal, onto nickel-based superalloy turbine parts is a viable method for substantially improving the lifetimes and maximum use temperatures of the parts. The method for joining the APMT plate to the superalloys is called evaporative metal bonding and involves placing a thin foil of zinc (Zn) between the plate and the superalloy, clamping them together, and heating in an atmosphere-controlled furnace. Upon heating, the Zn melts and dissolves the oxide skins of the alloys at the bond line, allowing the two alloys to diffuse into each other. The Zn then diffuses through the alloys and evaporates from their surfaces. Laboratory testing to determine the diffusion rate of Zn through the alloys has been completed. However, an analytical solution does not exist to model the diffusion of zinc through the alloys. For this reason, a finite difference algorithm using MATLAB was developed. It makes use of the hopscotch algorithm. The model allows the user to specify the dimensions of the metal parts, the Zn concentration at the bondline, the mesh size, time step, and Zn diffusivity. The experimentally measured values of diffusivity for Zn in APMT and Rene 80/CM 247LC are approximately 2.7 × 10-12 and 4 × 10-14 m2/s, respectively. While the qualitative behavior of the model appears correct, a comparison of the diffusion predictions with the experimental results from earlier in the project indicates that the expected Zn concentration is significantly higher than that measured experimentally. The difference depends on the assumed initial concentration, which is difficult to quantify exactly under experimental conditions for t = 0. In addition to the diffusion work, the coefficients of thermal expansions were determined for each of the alloys as a function of temperature. This information

  18. High-temperature oxidation/sulfidation resistance of iron-aluminide coatings

    SciTech Connect

    Tortorelli, P.F.; Wright, I.G.; Goodwin, G.M.; Howell, M.

    1996-04-01

    Iron aluminides containing > 20-25 at. % Al have oxidation and sulfidation resistance at temperatures well above those at which these alloys have adequate mechanical strength. Accordingly, these alloys may find application as coatings or claddings on more conventional higher-strength materials which are generally less corrosion-resistant at high temperatures. To this end, iron-aluminide coatings were prepared by gas tungsten arc and gas metal arc weld-overlay techniques. Specimens were cut from weld deposits and exposed to a highly aggressive oxidizing-sulfidizing (H2S-H2-H2O-Ar) environment at 800 C. All the weld overlayers showed good corrosion behavior under isothermal conditions, including a gas metal arc-produced deposit with only 21 at. % Al. Rapid degradation in corrosion resistance was observed under thermal cycling conditions when the initally grown scales spalled and the rate of reaction was then not controlled by formation of slowly growing Al oxide. Higher starting Al concentrations (> {approximately} 25 at. %) are needed to assure overall oxidation-sulfidation resistance of the weld overlays, but hydrogen cracking susceptibility must be minimized in order to physically separate the corrosive species from the reactive substrate material.

  19. Wear behaviour of wear-resistant adaptive nano-multilayered Ti-Al-Mo-N coatings

    NASA Astrophysics Data System (ADS)

    Sergevnin, V. S.; Blinkov, I. V.; Volkhonskii, A. O.; Belov, D. S.; Kuznetsov, D. V.; Gorshenkov, M. V.; Skryleva, E. A.

    2016-12-01

    Coating samples in the Ti-Al-Mo-N system were obtained by arc-PVD method at variable bias voltage Ub applied to the substrate, and the partial pressure of nitrogen P(N2) used as a reaction gas. The deposited coatings were characterized by a nanocrystalline structure with an average grain size of 30-40 nm and multilayered architecture with alternating layers of (Ti,Al)N nitride and Mo-containing phases with a thickness comparable to the grain size. Coatings of (Ti,Al)N-Mo-Mo2N and (Ti,Al)N-Mo2N compositions were obtained by changing deposition parameters. The obtained coatings had hardness of 40 GPa and the relative plastic deformation under microindentation up to 60%. (Ti,Al)N-Mo2N coatings demonstrated better physicomechanical characteristics, showing high resistance to crack formation and destruction through the plastic deformation mechanism without brittle fracturing, unlike (Ti,Al)N-Mo-Mo2N. The friction coefficient of the study coatings (against Al2O3 balls under dry condition using a pin-on-disc method) reached the values of 0.35 and 0.5 at 20 °C and 500 °C respectively, without noticeable wear within this temperature range. These tribological properties were achieved by forming MoO3 acting as a solid lubricant. At higher temperatures the deterioration in the tribological properties is due to the high rate of MoO3 sublimation from friction surfaces.

  20. Effect of Sr on the bioactivity and corrosion resistance of nanoporous niobium oxide coating for orthopaedic applications.

    PubMed

    Pauline, S Anne; Rajendran, N

    2014-03-01

    In this study, strontium incorporated Nb2O5 was synthesized in two different proportions by sol-gel methodology and was deposited on 316L SS by spin coating method. The synthesis conditions were optimized to obtain a nanoporous morphology. The prepared Sr-incorporated Nb2O5 coatings were uniform, smooth and well adherent on to the substrate 316L SS. The coatings were characterized by attenuated total reflectance-infrared spectroscopy (ATR-IR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM) and transmission electron microscopy (TEM) and the formation of Sr-incorporated Nb2O5 coatings with nanoporous morphology was confirmed. Static water contact angle measurements showed an enhancement in the wettability of the obtained coatings. In vitro bioactivity test of the coated substrates showed that 0.05M Sr-incorporated Nb2O5 coating had better bioactivity compared to 0.1M Sr-incorporated coating. Solution analysis studies confirmed the controlled release of Sr ions from the coating, which aid and enhance hydroxyapatite (HAp) growth. Electrochemical studies confirmed that the coatings provided excellent corrosion protection to the base material as increased charge transfer resistance and decreased double layer capacitance was observed for the coated substrates.

  1. Enhanced Corrosion Resistance of PVD-CrN Coatings by ALD Sealing Layers.

    PubMed

    Wan; Zhang, Teng Fei; Ding, Ji Cheng; Kim, Chang-Min; Park, So-Won; Yang, Yang; Kim, Kwang-Ho; Kwon, Se-Hun

    2017-12-01

    Multilayered hard coatings with a CrN matrix and an Al2O3, TiO2, or nanolaminate-Al2O3/TiO2 sealing layer were designed by a hybrid deposition process combined with physical vapor deposition (PVD) and atomic layer deposition (ALD). The strategy was to utilize ALD thin films as pinhole-free barriers to seal the intrinsic defects to protect the CrN matrix. The influences of the different sealing layers added in the coatings on the microstructure, surface roughness, and corrosion behaviors were investigated. The results indicated that the sealing layer added by ALD significantly decreased the average grain size and improved the corrosion resistance of the CrN coatings. The insertion of the nanolaminate-Al2O3/TiO2 sealing layers resulted in a further increase in corrosion resistance, which was attributed to the synergistic effect of Al2O3 and TiO2, both acting as excellent passivation barriers to the diffusion of corrosive substances.

  2. Combined slurry and cavitation erosion resistance of HVOF spray coated SS 410 steel

    NASA Astrophysics Data System (ADS)

    Amarendra, H. J.; Prathap, M. S.; Karthik, S.; Abhishek, A. M.; Madhu surya, K. C.; Gujjar gowda, S.; Anilkumar, T.

    2016-09-01

    The hydro turbine materials surface is degraded due to the slurry erosion and cavitation. The solid particles carried by water impacting the material results in slurry erosion. The damage occurred due to slurry erosion is the concern, when considered individually. The erosion damage is observed to be severe when slurry erosion and cavitation are combined. The hydro turbine material, martensitic stainless (SS 410) is surface modified with 80Ni-Cr by High Velocity Oxy Fuel spray process. The coated material subjected to post thermal treatment at a temperature of 950 ° C, soaked at 1 h, 2 h and 3 h are subjected to combined slurry and cavitation erosion test. The cavitation is created by using Cavitation Inducers. The tests are conducted by using silica sand as the erodent with three different sizes of 150, 200 and 300 μm. The results are compared with the as-received specimen. The results confirmed the effect of heat treatment on the end results, as the coated thermal treated specimens showed better erosion resistance against the as-received specimen. The eroded specimens are characterized by Scanning Electron Microscope. The thermal treated HVOF coated specimens shown the better erosion resistance.

  3. Microstructural Study on Oxidation Resistance of Nonmodified and Platinum Modified Aluminide Coating

    NASA Astrophysics Data System (ADS)

    Zagula-Yavorska, Maryana; Sieniawski, Jan

    2014-03-01

    Platinum electroplating layers (3 and 7 μm thick) were deposited on the surface of the Inconel 713 LC, CMSX 4, and Inconel 625 Ni-base superalloys. Diffusion treatment at 1050°C for 2 h under argon atmosphere was performed after electroplating. Diffusion treated samples were aluminized according to the low activity CVD process at 1050°C for 8 h. The nonmodified aluminide coatings consist of NiAl phase. Platinum modification let to obtain the (Ni,Pt)Al phase in coatings. The coated samples were subjected to cyclic oxidation testing at 1100°C. It was discovered that increase of the platinum electroplating thickness from 3 to 7 μm provides the improvement of oxidation resistance of aluminide coatings. Increase of the platinum thickness causes decreases in weight change and decreases in parabolic constant during oxidation. The platinum provides the pure Al2O3 oxide formation, slow growth oxide layer, and delay the oxide spalling during heating-cooling thermal cycles.

  4. Structural transformations in heat-resistant protective coatings on nickel alloys

    SciTech Connect

    Veksler, Yu.G.; Lesnikov, V.P.; Paleeva, S.Ya.; Lesnikova, E.G.; Myal'nitsa, G.F.

    1987-09-01

    In this work a comprehensive metallophysical study was carried out for two aluminosilicide slip coatings of the systems Al-Si and Al-Nb-Si and an electron-beam Co-Cr-Al-Y coating on alloy EP-539 (17...19% Cr, 4...6% Co, 2.5...4% W, 4.5...6.5% Mo, 2...3% Ti, 3...4% Al, 1.4...2% Nb, balance Ni) after high-temperature testing. The protective properties of the coatings were evaluated from the results of laboratory tests for heat resistance at 1000/sup 0/C in the combustion products of diesel fuel with added sulfur at 970, 1000, and 1060/sup 0/C for 100 h and after full-scale tests for 150, 250, 400, and 700 h. Metallographic, hardness, x-ray, and micro x-ray studies of the coating were carried out. Layer-by-layer phase composition and the lattice spacing of the main phases were determined. X-ray analysis was carried out in an a DRON-1 diffractometer in copper K/sub ..-->../-radiation, and x-ray microanalysis was carried out in a MS-46 Cameca microanalyzer

  5. Self-lubricating, low-friction, wear-resistant Al-based quasicrystalline coatings

    PubMed Central

    Silva Guedes de Lima, Bruno Alessandro; Medeiros Gomes, Rodinei; Guedes de Lima, Severino Jackson; Dragoe, Diana; Barthes-Labrousse, Marie-Geneviève; Kouitat-Njiwa, Richard; Dubois, Jean-Marie

    2016-01-01

    Abstract After gas atomization, a quasicrystalline powder based on aluminium was used to prepare a thick coating by high-velocity oxygen-fuel flame torch spraying. This layer was deposited on top of a bond-coat layer on a steel plate. A post-spraying annealing treatment turned the two layers to their stable state, a γ-brass crystal and an icosahedral quasicrystal, respectively. The projection parameters were selected in such a way that the coating behaved like a self-lubricating material, which offered very good wear resistance (duration of pin-on-disk tests superior to 5 km with negligible material loss) and low friction (µ ≤ 6% against sintered tungsten carbide), in contrast to the state of the art. This property was achieved thanks to, on the one hand, excellent bonding to the substrate via the bound coat, and on the other hand, presence at the boundaries between quasicrystalline flakes of a mixture of both threefold and fourfold coordinated carbon originating from spray processing. Application to hard materials used in mechanical devices is appealing, especially because soft, lubricating additives may not be needed, thus considerably increasing the lifetime of the devices and reducing waste of materials. PMID:27877859

  6. Self-lubricating, low-friction, wear-resistant Al-based quasicrystalline coatings.

    PubMed

    Silva Guedes de Lima, Bruno Alessandro; Medeiros Gomes, Rodinei; Guedes de Lima, Severino Jackson; Dragoe, Diana; Barthes-Labrousse, Marie-Geneviève; Kouitat-Njiwa, Richard; Dubois, Jean-Marie

    2016-01-01

    After gas atomization, a quasicrystalline powder based on aluminium was used to prepare a thick coating by high-velocity oxygen-fuel flame torch spraying. This layer was deposited on top of a bond-coat layer on a steel plate. A post-spraying annealing treatment turned the two layers to their stable state, a γ-brass crystal and an icosahedral quasicrystal, respectively. The projection parameters were selected in such a way that the coating behaved like a self-lubricating material, which offered very good wear resistance (duration of pin-on-disk tests superior to 5 km with negligible material loss) and low friction (µ ≤ 6% against sintered tungsten carbide), in contrast to the state of the art. This property was achieved thanks to, on the one hand, excellent bonding to the substrate via the bound coat, and on the other hand, presence at the boundaries between quasicrystalline flakes of a mixture of both threefold and fourfold coordinated carbon originating from spray processing. Application to hard materials used in mechanical devices is appealing, especially because soft, lubricating additives may not be needed, thus considerably increasing the lifetime of the devices and reducing waste of materials.

  7. Evaluating the thermal damage resistance of graphene/carbon nanotube hybrid composite coatings

    NASA Astrophysics Data System (ADS)

    David, L.; Feldman, A.; Mansfield, E.; Lehman, J.; Singh, G.

    2014-03-01

    We study laser irradiation behavior of multiwalled carbon nanotubes (MWCNT) and chemically modified graphene (rGO)-composite spray coatings for use as a thermal absorber material for high-power laser calorimeters. Spray coatings on aluminum test coupon were exposed to increasing laser irradiance for extended exposure times to quantify their damage threshold and optical absorbance. The coatings, prepared at varying mass % of MWCNTs in rGO, demonstrated significantly higher damage threshold values at 2.5 kW laser power at 10.6 μm wavelength than carbon paint or MWCNTs alone. Electron microscopy and Raman spectroscopy of irradiated specimens show that the coating prepared at 50% CNT loading endure at least 2 kW.cm-2 for 10 seconds without significant damage. The improved damage resistance is attributed to the unique structure of the composite in which the MWCNTs act as an efficient absorber of laser light while the much larger rGO sheets surrounding them, dissipate the heat over a wider area.

  8. Evaluating the thermal damage resistance of graphene/carbon nanotube hybrid composite coatings

    PubMed Central

    David, L.; Feldman, A.; Mansfield, E.; Lehman, J.; Singh, G.

    2014-01-01

    We study laser irradiation behavior of multiwalled carbon nanotubes (MWCNT) and chemically modified graphene (rGO)-composite spray coatings for use as a thermal absorber material for high-power laser calorimeters. Spray coatings on aluminum test coupon were exposed to increasing laser irradiance for extended exposure times to quantify their damage threshold and optical absorbance. The coatings, prepared at varying mass % of MWCNTs in rGO, demonstrated significantly higher damage threshold values at 2.5 kW laser power at 10.6 μm wavelength than carbon paint or MWCNTs alone. Electron microscopy and Raman spectroscopy of irradiated specimens show that the coating prepared at 50% CNT loading endure at least 2 kW.cm−2 for 10 seconds without significant damage. The improved damage resistance is attributed to the unique structure of the composite in which the MWCNTs act as an efficient absorber of laser light while the much larger rGO sheets surrounding them, dissipate the heat over a wider area. PMID:24603681

  9. Corrosion resistance of Zn-Al layered double hydroxide/poly(lactic acid) composite coating on magnesium alloy AZ31

    NASA Astrophysics Data System (ADS)

    Zeng, Rong-Chang; Li, Xiao-Ting; Liu, Zhen-Guo; Zhang, Fen; Li, Shuo-Qi; Cui, Hong-Zhi

    2015-12-01

    A Zn-Al layered double hydroxide (ZnAl-LDH) coating consisted of uniform hexagonal nano-plates was firstly synthesized by co-precipitation and hydrothermal treatment on the AZ31 alloy, and then a poly(lactic acid) (PLA) coating was sealed on the top layer of the ZnAl-LDH coating using vacuum freeze-drying. The characteristics of the ZnAl-LDH/PLA composite coatings were investigated by means of XRD, SEM, FTIR and EDS. The corrosion resistance of the coatings was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the ZnAl-LDH coating contained a compact inner layer and a porous outer layer, and the PLA coating with a strong adhesion to the porous outer layer can prolong the service life of the ZnAl-LDH coating. The excellent corrosion resistance of this composite coating can be attributable to its barrier function, ion-exchange and self-healing ability.

  10. Integration Process Development for Improved Compatibility with Organic Non-Porous Ultralow-k Dielectric Fluorocarbon on Advanced Cu Interconnects

    NASA Astrophysics Data System (ADS)

    Gu, Xun; Tomita, Yugo; Nemoto, Takenao; Miyatani, Kotaro; Saito, Akane; Kobayashi, Yasuo; Teramoto, Akinobu; Kuroda, Rihito; Kuroki, Shin-Ichiro; Kawase, Kazumasa; Nozawa, Toshihisa; Matsuoka, Takaaki; Sugawa, Shigetoshi; Ohmi, Tadahiro

    2012-05-01

    Integration of an organic non-porous ultralow-k dielectric, fluorocarbon (k= 2.2), into advanced Cu interconnects was demonstrated. The challenges of process-induced damage, such as delamination and variances of both the structure and electrical properties of the fluorocarbon during fabrication, were investigated on Cu/fluorocarbon damascene interconnects. A titanium-based barrier layer, instead of a tantalum-based barrier layer, was used to avoid delamination between Cu and fluorocarbon in Cu/fluorocarbon interconnects. A moisture-hermetic dielectric protective layer was also effective to avoid damage induced by wet chemical cleaning. On the other hand, a post-etching nitrogen plasma treatment to form a stable protective layer on the surface of the fluorocarbon was proposed for the practical minimization of damage introduction to fluorocarbon in the following damascene process, such as post-etching cleaning.

  11. Low-temperature radiation-resistant material for ball-bearing retainers

    NASA Technical Reports Server (NTRS)

    Desau, P. O.; Emmons, W. F.

    1970-01-01

    Radiation resistant material, made of polyimide polymers and S-glass cloth, is used in ball bearing retainers for extreme environments. Material displays satisfactory wear resistance, lubricity, and stability. Results of comparative tests with fluorocarbon materials are given.

  12. Micellization behavior of aromatic moiety bearing hybrid fluorocarbon sulfonate surfactants.

    PubMed

    Wadekar, Mohan N; Boekhoven, Job; Jager, Wolter F; Koper, Ger J M; Picken, Stephen J

    2012-02-21

    Aggregation behavior and thermodynamic properties of two novel homologous aromatic moiety bearing hybrid fluorocarbon surfactants, sodium 2-(2-(4-ethylphenyl)-1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoroethanesulfonate (1) and sodium 2-(1,1,2,2-tetrafluoro-2-(4-vinylphenyl)ethoxy)-1,1,2,2-tetrafluoroethanesulfonate (2) were studied using surface tension measurements and isothermal titration calorimetry (ITC) in dilute aqueous solutions at room temperature. Because of the aromatic group in the hydrophobic tail, both surfactants are soluble at room temperature unlike their starting precursor, 5-iodooctafluoro-3-oxapentanesulfonate as well as several other fluorocarbon sulfonic acid salts. Moreover, the surfactant 2 has the ability that it can be polymerized once microemulsions are formed with it. The ionic conductivity measurements of 1 at five different temperatures from 288 to 313 K were carried out to study the effect of temperature on the micellization and its thermodynamics. The pseudophase separation model was applied to estimate thermodynamic quantities from conductivity data. The Gibbs energy of micellization versus temperature exhibited the characteristic U-shaped behavior with a minimum at 306 K. The micellization process was found to be largely entropy driven. Because of its hybrid structure, the entropy change of micellization for 1 was larger than what is common for hydrocarbon surfactants like SDS but less than for fully fluorinated surfactants like NaPFO. The micellization process was found to be following the entropy-enthalpy compensation phenomena.

  13. Fluorocarbon 113 exposure and cardiac dysrhythmias among aerospace workers.

    PubMed

    Egeland, G M; Bloom, T F; Schnorr, T M; Hornung, R W; Suruda, A J; Wille, K K

    1992-01-01

    We investigated the cardiotoxic effects of 1,1,2-Trichloro-1,2,2- Trifluoroethane (fluorocarbon 113 or FC113) exposures among healthy workers cleaning rocket and ground support equipment for the National Aeronautic and Space Administration (NASA) programs. Exposure and ambulatory electrocardiographic (ECG) monitoring data were evaluated on 16 workers, each of whom was examined on exposed and nonexposed workdays. We examined whether there was a greater rate of dysrhythmias on an exposed workday relative to a nonexposed workday. Overall, we found no within subject differences in the rate of ventricular and supraventricular premature beats (number per 1,000 heart beats), fluctuations in the length of the P-R interval, or heart rate. We found that levels of FC113 exposures below the Occupational Safety and Health Administration (OSHA) 8-hour time-weighted-average (TWA) standard of 1,000 ppm did not induce cardiac dysrhythmias or subtle changes in cardiac activity. However, because fluorocarbons may sensitize the heart to epinephrine, this study's negative findings based on sedentary and fairly healthy workers may not be generalizable to other populations of workers who are not as healthy or engaged in more physically demanding work.

  14. Microstructure, bonding strength and thermal shock resistance of ceramic coatings on steels prepared by plasma electrolytic oxidation

    NASA Astrophysics Data System (ADS)

    Wang, Yunlong; Jiang, Zhaohua; Yao, Zhongping

    2009-11-01

    Ceramic coatings were successfully prepared on steel by plasma electrolytic oxidation (PEO) in aluminate electrolyte and silicate electrolyte, respectively. The microstructure of the coatings including surface morphology, phase and element composition were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The bonding strength between the ceramic coating and the substrate was tested using different methods including tensile tests and shearing tests. The thermal shock resistance of the coatings was also evaluated. The results indicated that coatings obtained in both electrolytes were porous and coarse. The average diameters of the pores were below 10 μm. PEO coatings obtained in aluminate electrolyte were composed of Fe 3O 4 and FeAl 2O 4, while those obtained in silicate electrolyte were in a noncrystal state. PEO coatings obtained in aluminate electrolyte showed similar change trend of tensile strength and shearing strength with increasing treating time, namely, a relatively high values with middle time treating and low value with short and long time treating. The best coating was the samples treated with 30 min, whose tensile strength was 20.6 MPa and shearing strength was 16 MPa. The tensile strength and shearing strength of coatings obtained in silicate electrolyte were not strongly influenced by the treating time, the values of which were range in 14 ± 2 MPa and 11 ± 2 MPa, respectively. Coatings obtained in both electrolytes showed the best thermal shock resistance with middle time treating. Coatings obtained in silicate electrolyte show a little better thermal shock resistance than those obtained in aluminate electrolyte.

  15. Transgenic Sugarcane Resistant to Sorghum mosaic virus Based on Coat Protein Gene Silencing by RNA Interference

    PubMed Central

    Guo, Jinlong; Gao, Shiwu; Lin, Qinliang; Wang, Hengbo; Que, Youxiong; Xu, Liping

    2015-01-01

    As one of the critical diseases of sugarcane, sugarcane mosaic disease can lead to serious decline in stalk yield and sucrose content. It is mainly caused by Potyvirus sugarcane mosaic virus (SCMV) and/or Sorghum mosaic virus (SrMV), with additional differences in viral strains. RNA interference (RNAi) is a novel strategy for producing viral resistant plants. In this study, based on multiple sequence alignment conducted on genomic sequences of different strains and isolates of SrMV, the conserved region of coat protein (CP) genes was selected as the target gene and the interference sequence with size of 423 bp in length was obtained through PCR amplification. The RNAi vector pGII00-HACP with an expression cassette containing both hairpin interference sequence and cp4-epsps herbicide-tolerant gene was transferred to sugarcane cultivar ROC22 via Agrobacterium-mediated transformation. After herbicide screening, PCR molecular identification, and artificial inoculation challenge, anti-SrMV positive transgenic lines were successfully obtained. SrMV resistance rate of the transgenic lines with the interference sequence was 87.5% based on SrMV challenge by artificial inoculation. The genetically modified SrMV-resistant lines of cultivar ROC22 provide resistant germplasm for breeding lines and can also serve as resistant lines having the same genetic background for study of resistance mechanisms. PMID:25685813

  16. The resistance to wear and corrosion of laser-cladding Al 2O 3 ceramic coating on Mg alloy

    NASA Astrophysics Data System (ADS)

    Gao, Ya-li; Wang, Cun-shan; Yao, Man; Liu, Hong-bin

    2007-04-01

    The paper presents a study on the preparation of Al 2O 3 ceramic coating on AZ91HP Mg alloy by laser remelting plasma-sprayed coating. It was found that after laser remelting, the coating exhibited obvious layer-like characteristics due to influence of temperature distribution, thermophysical parameters and layer thickness. According to the microstructural difference, the coating can be divided into the melted zone with the α-Al 2O 3 column-like crystal, the sintered zone with flock-like structure, the residual plasma-sprayed zone with loosened structure. Because of the dense column-like crystal, the hardness, wear and corrosion resistance of the laser remelted coating are much higher than those of the plasma-sprayed coating and as-received Mg alloy.

  17. Hardface coating systems and methods for metal alloys and other materials for wear and corrosion resistant applications

    SciTech Connect

    Seals, Roland D.

    2015-08-18

    The present disclosure relates generally to hardface coating systems and methods for metal alloys and other materials for wear and corrosion resistant applications. More specifically, the present disclosure relates to hardface coatings that include a network of titanium monoboride (TiB) needles or whiskers in a matrix, which are formed from titanium (Ti) and titanium diboride (TiB.sub.2) precursors by reactions enabled by the inherent energy provided by the process heat associated with coating deposition and, optionally, coating post-heat treatment. These hardface coatings are pyrophoric, thereby generating further reaction energy internally, and may be applied in a functionally graded manner. The hardface coatings may be deposited in the presence of a number of fluxing agents, beta stabilizers, densification aids, diffusional aids, and multimode particle size distributions to further enhance their performance characteristics.

  18. Structure and wear resistance of R6M5 steel based coatings

    NASA Astrophysics Data System (ADS)

    Gnyusov, S. F.; Ignatov, A. A.; Durakov, V. G.

    2010-08-01

    Features of the structure of R6M5 steel based coatings obtained by multiscan electron-beam fusion of a hardening composition in vacuum have been studied. It is established that the carbide subsystem of the hardened layer is characterized by a multimodal distribution of carbide particles with d 1 = 3.8 μm, d 2 = 0.65 μm, and d 3 < 0.25 μm. The volume fraction of M6C secondary carbide and retained matrix austenite can be controlled within broad limits by varying thermal parameters of the electron-beam fusion. An increase in the retained austenite fraction in the coating leads to improved wear resistance due to the γ → α' marten-site transformation during friction and the presence of dispersed secondary carbides inside the matrix grains.

  19. Method for providing uranium articles with a corrosion-resistant anodized coating

    DOEpatents

    Waldrop, F.B.; Washington, C.A.

    1981-01-07

    Uranium articles are provided with anodized oxide coatings in an aqueous solution of an electrolyte selected from the group consisting of potassium phosphate, potassium hydroxide, ammonium hydroxide, and a mixture of potassium tetraborate and boric acid. The uranium articles are anodized at a temperature greater than about 75/sup 0/C with a current flow of less than about 0.036 A/cm/sup 2/ of surface area while the pH of the solution is maintained in a range of about 2 to 11.5. The pH values of the aqueous solution and the low current density utilized during the electrolysis prevent excessive dissolution of the uranium and porosity in the film or watering. The relatively high temperature of the electrolyte bath inhibits hydration and the attendant deleterious pitting so as to enhance corrosion resistance of the anodized coating.

  20. Method for providing uranium articles with a corrosion resistant anodized coating

    DOEpatents

    Waldrop, Forrest B.; Washington, Charles A.

    1982-01-01

    Uranium articles are provided with anodized oxide coatings in an aqueous solution of an electrolyte selected from the group consisting of potassium phosphate, potassium hydroxide, ammonium hydroxide, and a mixture of potassium tetraborate and boric acid. The uranium articles are anodized at a temperature greater than about 75.degree. C. with a current flow of less than about 0.036 A/cm.sup.2 of surface area while the pH of the solution is maintained in a range of about 2 to 11.5. The pH values of the aqueous solution and the low current density utilized during the electrolysis prevent excessive dissolution of the uranium and porosity in the film or watering. The relatively high temperature of the electrolyte bath inhibits hydration and the attendant deleterious pitting so as to enhance corrosion resistance of the anodized coating.

  1. High Temperature Resistant Organopolysiloxane Coating for Protecting and Repairing Rigid Thermal Insulation

    NASA Technical Reports Server (NTRS)

    Leiser, Daniel B. (Inventor); Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

    1999-01-01

    Ceramics are protected from high temperature degradation, including high temperature, oxidative, aeroconvective degradation by a high temperature and oxidation resistant coating of a room temperature curing, hydrolyzed and partially condensed liquid polyorganosiloxane to the surface of the ceramic. The liquid polyorganosiloxane is formed by the hydrolysis and partial condensation of an alkyltrialkoxysilane with water or a mixture of an alkyltrialkoxysilane and a dialkyldialkoxysilane with water. The liquid polyorganosiloxane cures at room temperature on the surface of the ceramic to form a hard, protective, solid coating which forms a high temperature environment, and is also used as an adhesive for adhering a repair plug in major damage to the ceramic. This has been found useful for protecting and repairing porous, rigid ceramics of a type used on reentry space vehicles.

  2. Albumin coatings by alternating current electrophoretic deposition for improving corrosion resistance and bioactivity of titanium implants.

    PubMed

    Höhn, Sarah; Braem, Annabel; Neirinck, Bram; Virtanen, Sannakaisa

    2017-04-01

    Although Ti alloys are generally regarded to be highly corrosion resistant, inflammatory conditions following surgery can instigate breakdown of the TiO2 passivation layer leading to an increased metal ion release. Furthermore proteins present in the surrounding tissue will readily adsorb on a titanium surface after implantation. In this paper alternating current electrophoretic deposition (AC-EPD) of bovine serum albumin (BSA) on Ti6Al4V was investigated in order to increase the corrosion resistance and control the protein adsorption capability of the implant surface. The Ti6Al4V surface was characterized with SEM, XPS and ToF-SIMS after long-term immersion tests under physiological conditions and simulated inflammatory conditions either in Dulbecco's Modified Eagle Medium (DMEM) or DMEM supplemented with fetal calf serum (FCS). The analysis showed an increased adsorption of amino acids and proteins from the different immersion solutions. The BSA coating was shown to prevent selective dissolution of the vanadium (V) rich β-phase, thus effectively limiting metal ion release to the environment. Electrochemical impedance spectroscopy measurements confirmed an increase of the corrosion resistance for BSA coated surfaces as a function of immersion time due to the time-dependent adsorption of the different amino acids (from DMEM) and proteins (from FCS) as observed by ToF-SIMS analysis.

  3. Influence of polyetheretherketone coatings on the Ti-13Nb-13Zr titanium alloy's bio-tribological properties and corrosion resistance.

    PubMed

    Sak, Anita; Moskalewicz, Tomasz; Zimowski, Sławomir; Cieniek, Łukasz; Dubiel, Beata; Radziszewska, Agnieszka; Kot, Marcin; Łukaszczyk, Alicja

    2016-06-01

    Polyetheretherketone (PEEK) coatings of 70-90μm thick were electrophoretically deposited from a suspension of PEEK powder in ethanol on near-β Ti-13Nb-13Zr titanium alloy. In order to produce good quality coatings, the composition of the suspension (pH) and optimized deposition parameters (applied voltage and time) were experimentally selected. The as-deposited coatings exhibited the uniform distribution of PEEK powders on the substrate. The subsequent annealing at a temperature above the PEEK melting point enabled homogeneous, semi-crystalline coatings with spherulitic morphology to be produced. A micro-scratch test showed that the coatings exhibited very good adhesion to the titanium alloy substrate. Coating delamination was not observed even up to a maximal load of 30N. The PEEK coatings significantly improved the tribological properties of the Ti-13Nb-13Zr alloy. The coefficient of friction was reduced from 0.55 for an uncoated alloy to 0.40 and 0.12 for a coated alloy in a dry sliding and sliding in Ringer's solution, respectively. The PEEK coatings exhibited excellent wear resistance in both contact conditions. Their wear rate was more than 200 times smaller compared with the wear rate of the uncoated Ti-13Nb-13Zr alloy. The obtained results indicate that electrophoretically deposited PEEK coatings on the near-β titanium alloy exhibit very useful properties for their prospective tribological applications in medicine.

  4. Contact resistance and normal zone formation in coated yttrium barium copper oxide superconductors

    NASA Astrophysics Data System (ADS)

    Duckworth, Robert Calvin

    2001-11-01

    This project presents a systematic study of contact resistance and normal zone formation in silver coated YBa2CU3Ox (YBCO) superconductors. A unique opportunity exists in YBCO superconductors because of the ability to use oxygen annealing to influence the interfacial properties and the planar geometry of this type of superconductor to characterize the contact resistance between the silver and YBCO. The interface represents a region that current must cross when normal zones form in the superconductor and a high contact resistance could impede the current transfer or produce excess Joule heating that would result in premature quench or damage of the sample. While it has been shown in single-crystalline YBCO processing methods that the contact resistance of the silver/YBCO interface can be influenced by post-process oxygen annealing, this has not previously been confirmed for high-density films, nor for samples with complete layers of silver deposited on top of the YBCO. Both the influence of contact resistance and the knowledge of normal zone formation on conductor sized samples is essential for their successful implementation into superconducting applications such as transmission lines and magnets. While normal zone formation and propagation have been studied in other high temperature superconductors, the amount of information with respect to YBCO has been very limited. This study establishes that the processing method for the YBCO does not affect the contact resistance and mirrors the dependence of contact resistance on oxygen annealing temperature observed in earlier work. It has also been experimentally confirmed that the current transfer length provides an effective representation of the contact resistance when compared to more direct measurements using the traditional four-wire method. Finally for samples with low contact resistance, a combination of experiments and modeling demonstrate an accurate understanding of the key role of silver thickness and substrate

  5. Optimization of the HOVF Spray Parameters by Taguchi Method for High Corrosion-Resistant Fe-Based Coatings

    NASA Astrophysics Data System (ADS)

    Qin, Yujiao; Wu, Yuping; Zhang, Jianfeng; Hong, Sheng; Guo, Wenmin; Chen, Liyan; Liu, Hao

    2015-07-01

    Taguchi method was used to optimize the parameters of the high velocity oxygen fuel (HVOF) spray process and obtain the high corrosion-resistant Fe-based coatings. Based on the signal-to-noise ( S/ N) ratio and the analysis of variance, the significance of spray parameters in determining the porosity of the coatings was found to be in the order of spray distance, oxygen flow, and kerosene flow. Thus, the optimal parameters for the porosity of the HVOF sprayed Fe-based coating were determined as 280 mm for the spray distance, 963 scfh for the oxygen flow, and 28 gph for the kerosene flow. The potentiodynamic polarization and EIS tests indicated that the Fe-based coating prepared with the optimal parameters exhibited a higher corrosion potential ( E corr) of -196.14 mV, a lower corrosion current density ( i corr) of 0.14 μA/cm2, and a higher coating resistance ( R c) of 2.26 × 106 Ω cm2 than those of the hard chromium coating in 3.5% sodium chloride solution. This superior corrosion resistance could be attributed to the dense structure with low porosity and partially amorphous phases of the Fe-based coatings.

  6. Design and Performance Optimizations of Advanced Erosion-Resistant Low Conductivity Thermal Barrier Coatings for Rotorcraft Engines

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future rotorcraft engine higher fuel efficiency and lower emission goals. For thermal barrier coatings designed for rotorcraft turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability, because the rotorcraft are often operated in the most severe sand erosive environments. Advanced low thermal conductivity and erosion-resistant thermal barrier coatings are being developed, with the current emphasis being placed on thermal barrier coating toughness improvements using multicomponent alloying and processing optimization approaches. The performance of the advanced thermal barrier coatings has been evaluated in a high temperature erosion burner rig and a laser heat-flux rig to simulate engine erosion and thermal gradient environments. The results have shown that the coating composition and architecture optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic oxidation durability

  7. Fluorocarbon Fiber-Optic Raman Probe for Non-Invasive Raman Spectroscopy

    PubMed Central

    OKAGBARE, PAUL I.; MORRIS, MICHAEL D.

    2012-01-01

    We report the development of a novel fiber-optic Raman probe using a graded index fluorocarbon optical fiber. The fluorocarbon fiber has a simple Raman spectrum, a low fluorescence background, and generates a Raman signal that in turbid media serves as an intense reference Raman signal that corrects for albedo. The intensity of the reference signal can easily be varied as needed by scaling the length of the excitation fiber. Additionally, the fluorocarbon probe eliminates the broad silica Raman bands generated in conventional silica-core fiber without the need for filters. PMID:22732546

  8. Oxidation Resistance of Low-Temperature Pack Aluminizing Coatings on Ni-Base Superalloy

    NASA Astrophysics Data System (ADS)

    Yuan, Bifei; Yu, Longwen; Lu, Guiwu

    A nickel-base superalloy has been used to deposit the aluminide coating by low-temperature pack cementation process. The high temperature oxidation tests on aluminized alloys and the uncoated specimens are carried out at 1000°C for 10h. It is observed that a dense and protective Al2O3 surface layer is produced on the aluminized alloy, and the aluminizing process has greatly enhanced the high temperature oxidation resistance of the Ni-base superalloy at 1000°C. As a contrast, the uncoated specimen begins to be failure when treated only for 6h at the same temperature.

  9. Development of wear-resistant ceramic coatings for diesel engine components

    SciTech Connect

    Naylor, M.G.S. )

    1992-06-01

    The tribological properties of a variety of advanced coating materials have been evaluated under conditions which simulate the piston ring -- cylinder liner environment near top ring reversal in a heavy duty diesel engine. Coated ring'' samples were tested against a conventional pearlitic grey cast iron liner material using a high temperature reciprocating wear test rig. Tests were run with a fresh CE/SF 15W40lubricant at 200 and 350{degrees}C, with a high-soot, engine-tested oil at 200{degrees}C and with no lubrication at 200{degrees}C. For lowest wear under boundary lubricated conditions, the most promising candidates to emerge from this study were high velocity oxy-fuel (HVOF) Cr{sub 3} C{sub 2} - 20% NiCr and WC - 12% Co cermets, low temperature arc vapor deposited (LTAVD) CrN and plasma sprayed chromium oxides. Also,plasma sprayed Cr{sub 2}O{sub 3} and A1{sub 2}O{sub 3}-ZrO{sub 2} materials were found to give excellent wear resistance in unlubricated tests and at extremely high temperatures (450{degrees}C) with a syntheticoil. All of these materials would offer substantial wear reductions compared to the conventional electroplated hard chromium ring facing and thermally sprayed metallic coatings, especially at high temperatures and with high-soot oils subjected to degradation in diesel environments. The LTAVD CrN coating provided the lowest lubricated wear rates of all the materials evaluated, but may be too thin (4 {mu}m) for use as a top ring facing. Most of the coatings evaluated showed higher wear rates with high-soot, engine-tested oil than with fresh oil, with increases of more than a factor of ten in some cases. Generally, metallic materials were found to be much more sensitive to soot/oil degradation than ceramic and cermet coatings. Thus, decreased soot sensitivity'' is a significant driving force for utilizing ceramic or cermet coatings in diesel engine wear applications.

  10. Synthesis of silane coupling agents containing fluorocarbon chain and applications to dentistry: plaque-controlling surface modifiers.

    PubMed

    Yoshino, N; Teranaka, T

    1997-01-01

    Silane coupling agents containing a fluorocarbon chain were prepared in high yields. It was found that silanes can be useful modifiers of the surfaces of glass, metals, and resin composites for dental use. The silane coupling agent CF3(CF2)9CH2CH2Si(OCH3)3 was the best modifier of these surfaces in terms of water and oil repellency. Colorants and experimental bacterial plaque detached much more easily from, and adhered less well to, surfaces modified with this silane coupling agent compared with unmodified surfaces. The surfaces of four teeth of a denture were modified with this silane coupling agent by spreading the agent on the surfaces with a small brush followed by brief drying with a hair drier. The modified tooth surfaces of the denture, which was worn for four months in a heavy smoker's oral cavity, were more stain-resistant than the unmodified tooth surfaces. It is expected that silane coupling agents containing a fluorocarbon chain will be surface modifiers for enhancement of oral health.

  11. Robust Slippery Coating with Superior Corrosion Resistance and Anti-Icing Performance for AZ31B Mg Alloy Protection.

    PubMed

    Zhang, Jialei; Gu, Changdong; Tu, Jiangping

    2017-03-29

    Biomimetic slippery liquid-infused porous surfaces (SLIPSs) are developed as a potential alternative to superhydrophobic surfaces (SHSs) to resolve the issues of poor durability in corrosion protection and susceptibility to frosting. Herein, we fabricated a double-layered SLIPS coating on the AZ31 Mg alloy for corrosion protection and anti-icing application. The porous top layer was infused by lubricant, and the compact underlayer was utilized as a corrosion barrier. The water-repellent SLIPS coating exhibits a small sliding angle and durable corrosion resistance compared with the SHS coating. Moreover, the SLIPS coating delivers durable anti-icing performance for the Mg alloy substrate, which is obviously superior to the SHS coating. Multiple barriers in the SLIPS coating, including the infused water-repellent lubricant, the self-assembled monolayers coated porous top layer, and the compact layered double hydroxide-carbonate composite underlayer, are suggested as being responsible for the enhanced corrosion resistance and anti-icing performance. The robust double-layered SLIPS coating should be of great importance to expanding the potential applications of light metals and their alloys.

  12. Multi-functional hybrid coatings containing silica nanoparticles and anti-corrosive acrylate monomer for scratch and corrosion resistance.

    PubMed

    Seo, Ji Yeon; Han, Mijeong

    2011-01-14

    Multi-functional hybrid coatings having both anti-corrosion and scratch resistance were prepared from modified silica nanoparticles and functional acrylates. To improve the dispersion properties of silica nanoparticles in the organic/inorganic hybrid coatings, the surface of the nanoparticles was modified with γ-methacryloxypropyltrimethoxysilane. The coating solution could be prepared by mixing modified silica nanoparticles, tetrasiloxane acrylate, di-acrylate monomer containing an anti-corrosion functional group, acrylic acid, and an initiator in a solvent. The mixture was then dip-coated on iron substrates and finally polymerized by ultraviolet (UV) irradiation. Corrosion and scratch resistance of the coated iron was evaluated by electrochemical impedance spectroscopy (EIS) and a pencil hardness test, respectively. From the EIS results, the coatings with tetrasiloxane acrylate and di-acrylate did not show any decrease in impedance or phase angle, even after 50 days' exposure to 0.1 M NaCl electrolyte, whereas the conventional acrylate coatings started to fail after only 24 h. A hybrid coating containing the amine-quinone functional group exhibited excellent corrosion protection properties with 4-5H pencil hardness.

  13. Efficient resist edgebead removal for thick I-line resist coating application on TEL Mark 7 track sytem

    NASA Astrophysics Data System (ADS)

    Tran, Quang

    2000-08-01

    Photoresist coating process for IC device manufacturing requires correct target thickness, good uniformity and low defect density. For thick resist films used for Ion Implant, Top Metal layer and/or Pad masks, resist beads built up around the side edges and on top of wafer within 0-3 mm approximately from edges will need to be removed to eliminate defects during ion implantation and etch operations. The conventional method o f using solvent dispenses and optical exposure for edgebead removal does not necessarily solve this problem for resist thickness greater than 1.5 micron. For solvent EBR application, most resist track systems have both top and bottom dispenses nozzles for wafer edge cleaning. However, due to the high risk of unwanted EBR solvent splashes with top EBR nozzle onto wafer surface, which will destroy resist pattern resulting in yield loss, opt EBR solvent application is usually not used. Optical exposure system for wafer edges on the track equipment does not have enough power to completely expose thick photoresist film within a reasonable time for throughput requirement. Hence, the use of optical and backside EBRs only will result in incomplete resist edgebead removal. In this paper, we will describe a new top rinse nozzle design and a combined process of top and bottom EBRs to provide adequate and efficient resist removal around wafer edges for thick photoresist films. A low cost and easy modification to the existing standard to rinse nozzle fora TEL Mark 7 track system was done to provide efficient to solvent EBR application and to avoid solvent splash defects. The low angle to top rinse nozzle below 20 degrees was found to be important in reducing solvent droplet defects. The low angle of top rinse nozzle below 20 degrees was found to be important in reducing solvent droplet defects. Finally, a defect comparison study using KLS2132 will show a lower defect level for the modified top rinse nozzle than the standard one. Qualitative images of wafer

  14. Thermal fatigue resistance of NASA WAZ-20 alloy with three commercial coatings

    NASA Technical Reports Server (NTRS)

    Bizon, P. T.; Oldrieve, R. E.

    1975-01-01

    Screening tests using three commercial coatings (Jocoat, HI-15, and RT-1A) on the nickel-base alloy NASA WAZ-20 were performed by cyclic exposure in a Mach 1 burner facility. These tests showed Jocoated WAZ-20 to have the best cracking resistance. The thermal fatigue resistance of Jocoated WAZ-20 in both the random polycrystalline and directionally solidified polycrystalline forms relative to that of other superalloys was then evaluated in a fluidized-bed facility. This investigation showed that Jocoated random polycrystalline WAZ-20 ranked approximately in midrange in thermal fatigue life. The thermal fatigue life of directionally solidified Jocoated WAZ-20 was shorter than that of other directionally solidified alloys but still longer than that of all alloys in the random polycrystalline form.

  15. Conducting polymer-coated corrosion resistant metallic bipolar plates for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Joseph, Shine

    2005-11-01

    addition to this, metal dissolution can contaminate the membrane electrode assembly (MEA) and can cause system failure. These problems can be solved by coating the aluminum and stainless steel alloys with corrosion resistant and conductive polymers such as polyaniline and polypyrrole. These polymers can be applied to the metallic substrates by various methods such as electrochemical deposition, spraying and painting. Corrosion and contact resistance of the coated plates were tested under fuel cell conditions and showed promising results. Coatings were characterized by microscopy, infrared spectroscopy (FTIR) and cyclic voltammetry.

  16. Laser-resistance sensitivity to substrate pit size of multilayer coatings

    PubMed Central

    Chai, Yingjie; Zhu, Meiping; Wang, Hu; Xing, Huanbin; Cui, Yun; Sun, Jian; Yi, Kui; Shao, Jianda

    2016-01-01

    Nanosecond laser-resistance to dielectric multilayer coatings on substrate pits was examined with respect to the electric-field (E-field) enhancement and mechanical properties. The laser-induced damage sensitivity to the shape of the substrate pits has not been directly investigated through experiments, thus preventing clear understanding of the damage mechanism of substrate pits. We performed a systematic and comparative study to reveal the effects of the E-field distributions and localized stress concentration on the damage behaviour of coatings on substrates with pits. To obtain reliable results, substrate pits with different geometries were fabricated using a 520-nm femtosecond laser-processing platform. By using the finite element method, the E-field distribution and localized stress of the pitted region were well simulated. The 1064-nm damage morphologies of the coated pit were directly compared with simulated E-field intensity profiles and stress distributions. To enable further understanding, a simplified geometrical model was established, and the damage mechanism was introduced. PMID:27252016

  17. Surface Design and Engineering Toward Wear-Resistant, Self-Lubricating Diamond Films and Coatings

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1999-01-01

    The tribological properties of chemical-vapor-deposited (CVD) diamond films vary with the environment, possessing a Jekyll-and-Hyde character. CVD diamond has low coefficient of friction and high wear resistance in air but high coefficient of friction and low wear resistance in vacuum. Improving the tribological functionality of materials (such as achieving low friction and good wear resistance) was an aim of this investigation. Three studies on the surface design, surface engineering, and tribology of CVD diamond have shown that its friction and wear are significantly reduced in ultrahigh vacuum. The main criteria for judging whether diamond films are an effective wear-resistant, self-lubricating material were coefficient of friction and wear rate, which must be less than 0.1 and on the order of 10(exp 6) cu mm/N(dot)m, respectively. In the first study the presence of a thin film (less than 1 micron thick) of amorphous, nondiamond carbon (hydrogenated carbon, also called diamondlike carbon or DLC) on CVD diamond greatly decreased the coefficient of friction and the wear rate. Therefore, a thin DLC film on CVD diamond can be an effective wear-resistant, lubricating coating in ultrahigh vacuum. In the second study the presence of an amorphous, nondiamond carbon surface layer formed on CVD diamond by ion implantation significantly reduced the coefficient of friction and the wear rate in ultrahigh vacuum. Therefore, such surface layers are acceptable for effective self-lubricating, wear-resistant applications of CVD diamond. In the third study CVD diamond in contact with cubic boron nitride exhibited low coefficient of friction in ultra high vacuum. Therefore, this materials combination can provide an effective self-lubricating, wear-resistant couple in ultrahigh vacuum.

  18. Corrosion resistance of multilayer hybrid sol-gel coatings deposited on the AISI 316L austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Caballero, Y. T.; Rondón, E. A.; Rueda, L.; Hernández Barrios, C. A.; Coy, A.; Viejo, F.

    2016-02-01

    In the present work multilayer hybrid sol-gel coatings were synthesized on the AISI 316L austenitic stainless steel employed in the fabrication of orthopaedic implants. Hybrid sols were obtained from a mixture of inorganic precursor, TEOS, and organic, GPTMS, using ethanol as solvent, and acetic acid as catalyst. The characterization of the sols was performed using pH measurements, rheological tests and infrared spectroscopy (FTIR) for different ageing times. On the other hand, the coatings were characterized by scanning electron microscopy (SEM), while the corrosion resistance was evaluated using anodic potentiodynamic polarization in SBF solution at 37±2°C. The results confirmed that sol-gel synthesis employing TEOS-GPTMS systems produces uniform and homogeneous coatings, which enhanced the corrosion resistance with regard to the parent alloy. Moreover, corrosion performance was retained after applying more than one layer (multilayer coatings).

  19. Optical coatings of variable refractive index and high laser-resistance from physical-vapor-deposited perfluorinated amorphous polymer

    DOEpatents

    Chow, Robert; Loomis, Gary E.; Thomas, Ian M.

    1999-01-01

    Variable index optical single-layers, optical multilayer, and laser-resistant coatings were made from a perfluorinated amorphous polymer material by physical vapor deposition. This was accomplished by physically vapor depositing a polymer material, such as bulk Teflon AF2400, for example, to form thin layers that have a very low refractive index (.about.1.10-1.31) and are highly transparent from the ultra-violet through the near infrared regime, and maintain the low refractive index of the bulk material. The refractive index can be varied by simply varying one process parameter, either the deposition rate or the substrate temperature. The thus forming coatings may be utilized in anti-reflectors and graded anti-reflection coatings, as well as in optical layers for laser-resistant coatings at optical wavelengths of less than about 2000 nm.

  20. Optical coatings of variable refractive index and high laser-resistance from physical-vapor-deposited perfluorinated amorphous polymer

    DOEpatents

    Chow, R.; Loomis, G.E.; Thomas, I.M.

    1999-03-16

    Variable index optical single-layers, optical multilayer, and laser-resistant coatings were made from a perfluorinated amorphous polymer material by physical vapor deposition. This was accomplished by physically vapor depositing a polymer material, such as bulk Teflon AF2400, for example, to form thin layers that have a very low refractive index (ca. 1.10--1.31) and are highly transparent from the ultra-violet through the near infrared regime, and maintain the low refractive index of the bulk material. The refractive index can be varied by simply varying one process parameter, either the deposition rate or the substrate temperature. The thus forming coatings may be utilized in anti-reflectors and graded anti-reflection coatings, as well as in optical layers for laser-resistant coatings at optical wavelengths of less than about 2000 nm. 2 figs.

  1. Influence of Handling Parameters on Coating Characteristics in Order to Produce Near-Net-Shape Wear Resistant Coatings

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Krebs, B.

    2012-06-01

    The present study investigates the influence of spray torch handling parameters such as the spray angle, spray distance, track pitch, and gun velocity on the deposition rate and the microstructure of atmospheric plasma sprayed WC-12Co coatings as well as twin wire arc sprayed WSC-Fe coatings. Similarities as well as fundamental differences in the sensitivity of the two spray processes, regarding changes in handling parameters are discussed, using results of light microscopic analyses. Both coating systems show distinct changes of the deposition rate when varying the handling parameters. An empirical model could be determined to describe the coating deposition. This model enables an optimization of path planning processes by reducing the number of optimization loops. However, the coatings show visible changes in the microstructure, which have to be taken into consideration in order to guarantee the production of high quality coatings.

  2. Searching for optimal mitigation geometries for laser resistant multilayer high reflector coatings

    SciTech Connect

    Qiu, S R; Wolfe, J E; Monterrosa, A M; Feit, M D; Pistor, T V; STolz, C J

    2011-02-11

    Growing laser damage sites on multilayer high reflector coatings can limit mirror performance. One of the strategies to improve laser damage resistance is to replace the growing damage sites with pre-designed benign mitigation structures. By mitigating the weakest site on the optic, the large aperture mirror will have a laser resistance comparable to the intrinsic value of the multilayer coating. To determine the optimal mitigation geometry, the finite difference time domain method (FDTD) was used to quantify the electric-field intensification within the multilayer, at the presence of different conical pits. We find that the field intensification induced by the mitigation pit is strongly dependent on the polarization and the angle of incidence (AOI) of the incoming wave. Therefore the optimal mitigation conical pit geometry is application specific. Furthermore, our simulation also illustrates an alternative means to achieve an optimal mitigation structure by matching the cone angle of the structure with the AOI of the incoming wave, except for the p-polarization wave at a range of incident angles between 30{sup o} and 45{sup o}.

  3. Dross formation mechanism and development of wear resistant scraper in aluminum-silicon-zinc coating bath

    NASA Astrophysics Data System (ADS)

    Varadarajan, Ashok

    Steel sheet manufacturers across the globe, face a huge loss of production due to the molten metal corrosion of the pot hardware in continuous galvanizing lines. The development of steel sheet with corrosion resistant for more than 30 years using a high aluminum content zinc coating has made an impact in the construction industry. High aluminum content bath (55 wt%) causes severe corrosion of the pot hardware and causes huge repair and replacement cost with frequent stoppages. One of the main reasons for stoppages is the severe dross formation over the submerged hardware (sink roll), which results in poor coating layer over the steel sheet. Complete understanding of the mechanism of the dross formation over the submerged hardware has not yet been completely achieved. In order to establish the dross formation mechanism, an array of tests was performed. Initial inhibition of Al attack by the silicon rich layer and further formation of Fe2Al 5 layer hindering the diffusion of the Al into the substrate were observed. Also, the effect of the hydrodynamic motion of the bathe in the dross formation mechanism was established. A series of tests for efficient removal of the dross formed over the sink roll using high hardness, corrosion resistant materials were conducted at 600°C. After these tests, an efficient scraping process with a potential for energy and cost savings was developed with a better scraper material, resulting in a reduction of 75% in line stoppages.

  4. Development of wear resistant ceramic coatings for diesel engine components. Final report

    SciTech Connect

    Haselkorn, M.H.

    1992-04-01

    Improved fuel economy and a reduction of emissions can be achieved by insulation of the combustion chamber components to reduce heat rejection. However, insulating the combustion chamber components will also increase the operating temperature of the piston ring/cylinder liner interface from approximately 150{degree}C to over 300{degree}C. Existing ring/liner materials can not withstand these higher operating temperatures and for this reason, new materials need to be developed for this critical tribological interface. The overall goal of this program is the development of piston ring/cylinder liner material pairs which would be able to provide the required friction and wear properties at these more severe operating conditions. More specifically, this program first selected, and then evaluated, potential d/wear resistant coatings which could be applied to either piston rings an or cylinder liners and provide, at 350{degree}C under lubricated conditions, coefficients of friction below 0.1 and wear rates of less than 25 {times} lO{sup {minus}6} mm/hour. The processes selected for applying the candidate wear resistant coatings to piston rings and/or cylinder liners were plasma spraying, chemical vapor, physical vapor and low temperature arc vapor deposition techniques as well as enameling techniques.

  5. Selected fretting-wear-resistant coatings for titanium - 6-percent-aluminum - 4-percent-vanadium alloy

    NASA Technical Reports Server (NTRS)

    Bill, R. C.

    1976-01-01

    A titanium - 6-percent-aluminum - 4-percent-vanadium alloy (Ti-6Al-4V) was subjected to fretting-wear exposures against uncoated Ti-6Al-4V as a baseline and against various coatings and surface treatments applied to Ti-6Al-4V. The coatings evaluated included plasma-sprayed tungsten carbide with 12 percent cobalt, aluminum oxide with 13 percent titanium oxide, chromium oxide, and aluminum bronze with 10 percent aromatic polyester; polymer-bonded polyimide, polyimide with graphite fluoride, polyimide with molybdenum disulfide (MoS2), and methyl phenyl silicone bonded MoS2, preoxidation surface treatment, a nitride surface treatment, and a sputtered MoS2 coating. Results of wear measurements on both the coated and uncoated surfaces after 300,000 fretting cycles indicated that the polyimide coating was the most wear resistant and caused the least wear to the uncoated mating surface.

  6. Microbubbles with a Self-Assembled Poloxamer Shell and a Fluorocarbon Inner Gas.

    PubMed

    Ando, Yu; Tabata, Hiraku; Sanchez, Michaël; Cagna, Alain; Koyama, Daisuke; Krafft, Marie Pierre

    2016-11-29

    The numerous applications of microbubbles in food science and medicine call for a better understanding and control of the effects of the properties of their shells on their stability and ability to resonate at chosen frequencies when submitted to an ultrasound field. We have investigated both millimetric and micrometric bubbles stabilized by an amphiphilic block copolymer, Poloxamer 188 (e.g., Pluronic F-68). Although Pluronic F-68 is routinely being used as a dispersing and foaming agent to facilitate phospholipid-based microbubble preparation, it has never been studied as a shell component per se. First, we investigated the adsorption kinetics of Pluronic F-68 at the interface between water and air, or air saturated with vapors of perfluorohexane (F-hexane), using bubble profile tensiometry analysis. F-Hexane was found to strongly accelerate the adsorption of Pluronic F-68 (at low concentrations) and decrease the interfacial tension values at equilibrium (at all concentrations). We also found that relatively stable microbubbles could unexpectedly be prepared from Pluronic F-68 in the absence of any other surfactant, but only when F-hexane was present. These bubbles showed an only limited volume increase over ∼3 h, while a 10-fold increase in size occurred within 200 s in the absence of a fluorocarbon. Remarkably, their deflation rate decreased when the Pluronic F-68 concentration decreased, suggesting that bubbles with semidilute copolymer coverage are more stable than those more densely covered by copolymer brushes. Single-bubble experiments using laser Doppler vibratometry showed that, by contrast with other surfactant-coated microbubbles, the resonance radius of the Pluronic F-68-coated microbubbles was lower than that of naked microbubbles, meaning that they are less elastic. It was also found that the bubble's vibrational displacement amplitude decreased substantially when the microbubbles were covered with Pluronic F-68, an effect that was further

  7. An effective and novel pore sealing agent to enhance the corrosion resistance performance of Al coating in artificial ocean water.

    PubMed

    Lee, Han-Seung; Singh, Jitendra Kumar; Ismail, Mohamed A

    2017-02-03

    A new technique was accepted to fill the porosity of Al coating applied by arc thermal spray process to enhance corrosion resistance performance in artificial ocean water. The porosity is the inherent property of arc thermal spray coating process. In this study, applied coating was treated with different concentrations of ammonium phosphate mono basic (NH4H2PO4: AP) solution thereafter dried at room temperature and kept in humidity chamber for 7d to deposit uniform film. The corrosion resistance of Al coating and treated samples have been evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic techniques with exposure periods in artificial ocean water. Electrochemical techniques, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) indicated that phosphate ion would have been retarding corrosion of Al coating effectively. The formation of AHP (Ammonium Aluminum Hydrogen Phosphate Hydrate: NH4)3Al5H6(PO4)8.18H2O) on Al coating surface after treatment with AP is nano sized, crystalline and uniformly deposited but after exposure them in artificial ocean water, they form AHPH (Aluminum hydroxide phosphate hydrate Al3(PO4)2(OH)3(H2O)5) that is very protective, adherent, uniform and plate like morphology of corrosion products. The AHPH is sparingly soluble and adherent to surface and imparted improved corrosion resistance.

  8. A nanocrystalline zirconium carbide coating as a functional corrosion-resistant barrier for polymer electrolyte membrane fuel cell application

    NASA Astrophysics Data System (ADS)

    Xu, Jiang; Li, ZhengYang; Xu, Song; Munroe, Paul; Xie, Zong-Han

    2015-11-01

    A ZrC nanocrystalline coating is engineered onto a Ti-6Al-4V substrate using a double cathode glow discharge technique in order to improve the corrosion resistance and long-term stability of this alloy. The new coating exhibits an extremely dense, homogeneous microstructure composed of equiaxed grains with an average grain size of ∼12 nm and is well adhered on the surface of the substrate. The corrosion behaviour of the coating is systematically investigated using various electrochemical methods, including potentiodynamic, potentiostatic polarizations and electrochemical impedance spectroscopy (EIS), in a simulated polymer electrolyte membrane fuel cell (PEMFC) operating circumstances under different temperatures. The results show that with rising temperature, the corrosion potential (Ecorr) decreases and the corrosion current density (icorr) of the ZrC coated specimen increases, indicating that the corrosion resistance decreased with increasing temperature. However, at a given temperature, the ZrC-coated Ti-6Al-4V alloy has a higher Ecorr and lower icorr as compared to the bare substrate. The results of EIS measurements show that the values of the resistance for the ZrC coated Ti-6Al-4V alloy are three orders of magnitude larger than those of Ti-6A1-4V in the simulated PEMFC environment.

  9. Enhancement of oxidation resistance of graphite foams by polymer derived-silicon carbide coating for concentrated solar power applications

    SciTech Connect

    Kim, T.; Singh, D.; Singh, M.

    2015-05-01

    Graphite foam with extremely high thermal conductivity has been investigated to enhance heat transfer of latent heat thermal energy storage (LHTES) systems. However, the use of graphite foam for elevated temperature applications (>600 °C) is limited due to poor oxidation resistance of graphite. In the present study, oxidation resistance of graphite foam coated with silicon carbide (SiC) was investigated. A pre-ceramic polymer derived coating (PDC) method was used to form a SiC coating on the graphite foams. Post coating deposition, the samples were analyzed by scanning electron microscopy and energy dispersive spectroscopy. The oxidation resistance of PDC-SiC coating was quantified by measuring the weight of the samples at several measuring points. The experiments were conducted under static argon atmosphere in a furnace. After the experiments, oxidation rates (%/hour) were calculated to predict the lifetime of the graphite foams. The experimental results showed that the PDC-SiC coating could prevent the oxidation of graphite foam under static argon atmosphere up to 900 °C.

  10. Enhancement of oxidation resistance of graphite foams by polymer derived-silicon carbide coating for concentrated solar power applications

    DOE PAGES

    Kim, T.; Singh, D.; Singh, M.

    2015-05-01

    Graphite foam with extremely high thermal conductivity has been investigated to enhance heat transfer of latent heat thermal energy storage (LHTES) systems. However, the use of graphite foam for elevated temperature applications (>600 °C) is limited due to poor oxidation resistance of graphite. In the present study, oxidation resistance of graphite foam coated with silicon carbide (SiC) was investigated. A pre-ceramic polymer derived coating (PDC) method was used to form a SiC coating on the graphite foams. Post coating deposition, the samples were analyzed by scanning electron microscopy and energy dispersive spectroscopy. The oxidation resistance of PDC-SiC coating was quantifiedmore » by measuring the weight of the samples at several measuring points. The experiments were conducted under static argon atmosphere in a furnace. After the experiments, oxidation rates (%/hour) were calculated to predict the lifetime of the graphite foams. The experimental results showed that the PDC-SiC coating could prevent the oxidation of graphite foam under static argon atmosphere up to 900 °C.« less

  11. An effective and novel pore sealing agent to enhance the corrosion resistance performance of Al coating in artificial ocean water

    PubMed Central

    Lee, Han-Seung; Singh, Jitendra Kumar; Ismail, Mohamed A.

    2017-01-01

    A new technique was accepted to fill the porosity of Al coating applied by arc thermal spray process to enhance corrosion resistance performance in artificial ocean water. The porosity is the inherent property of arc thermal spray coating process. In this study, applied coating was treated with different concentrations of ammonium phosphate mono basic (NH4H2PO4: AP) solution thereafter dried at room temperature and kept in humidity chamber for 7d to deposit uniform film. The corrosion resistance of Al coating and treated samples have been evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic techniques with exposure periods in artificial ocean water. Electrochemical techniques, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) indicated that phosphate ion would have been retarding corrosion of Al coating effectively. The formation of AHP (Ammonium Aluminum Hydrogen Phosphate Hydrate: NH4)3Al5H6(PO4)8.18H2O) on Al coating surface after treatment with AP is nano sized, crystalline and uniformly deposited but after exposure them in artificial ocean water, they form AHPH (Aluminum hydroxide phosphate hydrate Al3(PO4)2(OH)3(H2O)5) that is very protective, adherent, uniform and plate like morphology of corrosion products. The AHPH is sparingly soluble and adherent to surface and imparted improved corrosion resistance. PMID:28157233

  12. An effective and novel pore sealing agent to enhance the corrosion resistance performance of Al coating in artificial ocean water

    NASA Astrophysics Data System (ADS)

    Lee, Han-Seung; Singh, Jitendra Kumar; Ismail, Mohamed A.

    2017-02-01

    A new technique was accepted to fill the porosity of Al coating applied by arc thermal spray process to enhance corrosion resistance performance in artificial ocean water. The porosity is the inherent property of arc thermal spray coating process. In this study, applied coating was treated with different concentrations of ammonium phosphate mono basic (NH4H2PO4: AP) solution thereafter dried at room temperature and kept in humidity chamber for 7d to deposit uniform film. The corrosion resistance of Al coating and treated samples have been evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic techniques with exposure periods in artificial ocean water. Electrochemical techniques, X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) indicated that phosphate ion would have been retarding corrosion of Al coating effectively. The formation of AHP (Ammonium Aluminum Hydrogen Phosphate Hydrate: NH4)3Al5H6(PO4)8.18H2O) on Al coating surface after treatment with AP is nano sized, crystalline and uniformly deposited but after exposure them in artificial ocean water, they form AHPH (Aluminum hydroxide phosphate hydrate Al3(PO4)2(OH)3(H2O)5) that is very protective, adherent, uniform and plate like morphology of corrosion products. The AHPH is sparingly soluble and adherent to surface and imparted improved corrosion resistance.

  13. Cyclotriphosphazene and TiO2 reinforced nanocomposite coated on mild steel plates for antibacterial and corrosion resistance applications

    NASA Astrophysics Data System (ADS)

    Krishnadevi, Krishnamoorthy; Selvaraj, Vaithilingam

    2016-03-01

    The mild steel surface has been modified to impart anticorrosion and antibacterial properties through a dip coating method followed by thermal curing of a mixture containing amine terminated cyclotriphosphazene and functionalized titanium dioxide nanoparticles reinforced benzoxazine based cyanate ester composite (ATCP/FTiO2/Bz-CE). The corrosion resistance behavior of coating material has been investigated by electrochemical and antibacterial studies by disc diffusion method. The nanocomposites coated mild steels have displayed a good chemical stability over long immersion in a corrosive environment. The protection efficiency has found to be high for ATCP/FTiO2/Bz-CE composites, which can be used in microelectronics and marine applications.

  14. Multifunctional composite coating as a wear-resistant layer for the bearing in total hip joint replacement.

    PubMed

    Cho, Seung Mok; Park, Jin-Woo; Han, Hyung-Seop; Seok, Hyun-Kwang; Moon, Myoung-Woon; Kim, Yu Chan

    2013-01-23

    In this study, we developed Ti-TiN composite coatings with fine lamellar structures for use as an enhanced wear-resistant layer between the bearing components of the polymer-lined acetabular cup and the metal femoral head of total hip joint replacements (THRs). A plasma spraying deposition method was used to apply the composite coatings, and the thickness of TiN layer in the composite could be controlled by varying the flow rate of N(2) atmospheric gas. The surface properties, such as roughness and hardness, were analyzed, and the friction coefficient (μ) and wear rate (k) were measured using a bovine serum wear test. A biocompatibility test was performed to evaluate the toxicity of the composite coatings. Our experimental results reveal that the friction and wear resistance of composite coatings is superior to that of the metallic implant materials, and they have a higher level of fracture toughness as compared with other ceramic coatings because of a good balance between the hardness of the TiN and the toughness of the Ti. Furthermore, these coatings possessed excellent biocompatibility. The experimental results also demonstrate that the improved wear properties can be attributed to a certain level of unavoidable porosity that is due to the rapid solidification of liquid droplets during the plasma spraying process. The pores in the coating surface play an important role as a lubricant (bovine serum) reservoir, reducing the actual contact area and friction losses.

  15. Preparation of the Multi-Walled Carbon Nanotubes/Nickel Composite Coating with Superior Wear and Corrosion Resistance

    NASA Astrophysics Data System (ADS)

    Li, Xuewu; Gu, Yang; Shi, Tian; Peng, Dai; Tang, Mingkai; Zhang, Qiaoxin; Huang, Xingjiu

    2015-12-01

    The multi-walled carbon nanotubes/nickel (MWCNTs/Ni) nanocomposite coatings were prepared on Cu substrate by electro-deposition method in the electrolyte with well-dispersed MWCNTs. Surface morphologies of the composite coatings with protrusion structures were confirmed by scanning electron microscopy. X-ray diffraction, fourier transform infrared spectroscopy, and energy-dispersive x-ray spectrometer were used to characterize the phase structures, functional groups, and elements distribution of the coatings as well as the incorporated MWCNTs. In addition, the effect of MWCNTs percentage on thickness, hardness, wear, and corrosion resistance of the coatings was also investigated. Results indicated that the incorporation of MWCNTs positively affected the hardness of coatings for their strengthening skeletons effect. Meanwhile, the coating with the MWCNTs concentration of 0.2 g/L could achieve the lowest friction coefficient, wear rate as well as the mass loss in the tribological test by a ball-on-disk tribometer. And also, the optimal corrosion resistance with the highest corrosion potential ( E corr) and the lowest corrosion current density ( I corr) of the composite coating was finally proved after the potentiodynamic polarization evaluation, which could promote the potential applications in preparing the functional nanocomposite materials.

  16. [Study on discrimination of varieties of fire resistive coating for steel structure based on near-infrared spectroscopy].

    PubMed

    Xue, Gang; Song, Wen-qi; Li, Shu-chao

    2015-01-01

    In order to achieve the rapid identification of fire resistive coating for steel structure of different brands in circulating, a new method for the fast discrimination of varieties of fire resistive coating for steel structure by means of near infrared spectroscopy was proposed. The raster scanning near infrared spectroscopy instrument and near infrared diffuse reflectance spectroscopy were applied to collect the spectral curve of different brands of fire resistive coating for steel structure and the spectral data were preprocessed with standard normal variate transformation(standard normal variate transformation, SNV) and Norris second derivative. The principal component analysis (principal component analysis, PCA)was used to near infrared spectra for cluster analysis. The analysis results showed that the cumulate reliabilities of PC1 to PC5 were 99. 791%. The 3-dimentional plot was drawn with the scores of PC1, PC2 and PC3 X 10, which appeared to provide the best clustering of the varieties of fire resistive coating for steel structure. A total of 150 fire resistive coating samples were divided into calibration set and validation set randomly, the calibration set had 125 samples with 25 samples of each variety, and the validation set had 25 samples with 5 samples of each variety. According to the principal component scores of unknown samples, Mahalanobis distance values between each variety and unknown samples were calculated to realize the discrimination of different varieties. The qualitative analysis model for external verification of unknown samples is a 10% recognition ration. The results demonstrated that this identification method can be used as a rapid, accurate method to identify the classification of fire resistive coating for steel structure and provide technical reference for market regulation.

  17. Effect of La2O3 on High-Temperature Oxidation Resistance of Electrospark Deposited Ni-BASED Coatings

    NASA Astrophysics Data System (ADS)

    Gao, Yuxin; Yi, Jian; Fang, Zhigang; Cheng, Hu

    2014-08-01

    The oxidation tests of electrospark deposited Ni-based coatings without and with 2.5 wt.% La2O3 were conducted at 960°C in air for 100 h. The oxidation kinetic of the coatings was studied by testing the weight gain. The phase structures and morphologies of the oxidized coatings were investigated by XRD and SEM. The experimental results show that the coatings with 2.5 wt.% La2O3 exhibits excellent high-temperature oxidation resistance including low oxidation rate and improved spallation resistance, due to the formation of a denser and more adherent oxide scale compared with that without La2O3. The effects of La2O3 on the oxidation resistance include the following two aspects: First, refinement of the coating grains promotes the selective oxidation of Cr, leading to the formation of protective chromia scale in a short time, and second, refinement of the oxide grains enhances the high-temperature creep rate, resulting in decrease of inner stress and improvement of spallation resistance of the oxide layer.

  18. Reinforced Carbon Carbon (RCC) oxidation resistant material samples - Baseline coated, and baseline coated with tetraethyl orthosilicate (TEOS) impregnation

    NASA Technical Reports Server (NTRS)

    Gantz, E. E.

    1977-01-01

    Reinforced carbon-carbon material specimens were machined from 19 and 33 ply flat panels which were fabricated and processed in accordance with the specifications and procedures accepted for the fabrication and processing of the leading edge structural subsystem (LESS) elements for the space shuttle orbiter. The specimens were then baseline coated and tetraethyl orthosilicate impregnated, as applicable, in accordance with the procedures and requirements of the appropriate LESS production specifications. Three heater bars were ATJ graphite silicon carbide coated with the Vought 'pack cementation' coating process, and three were stackpole grade 2020 graphite silicon carbide coated with the chemical vapor deposition process utilized by Vought in coating the LESS shell development program entry heater elements. Nondestructive test results are reported.

  19. Wear Resistant Carbide-based Thermal Sprayed Coatings: Process, Properties, Mechanical Degradation and Wear

    NASA Astrophysics Data System (ADS)

    Ghabchi, Arash

    Thermally sprayed ceramic-metallic composite (CerMet) materials consist of ceramic particles mainly in form of carbides reinforced by metallic binder exhibit unique microstructural and mechanical characteristics. Such structure brings in a novel combination of hardness and toughness enabling application of this class of material in wear resistant surfaces. Final deposit microstructure that defines the mechanical properties and wear performance of material depends on process parameters and starting material characteristics. Complex interaction of in-flight particles with supersonic flame, formation of complex defective deposit structure comprising of pores, cracks and splat boundaries make comprehending of interrelation of process, microstructure, properties and performance a difficult task. Additional challenge is development of systematic understanding on mechanical degradation, damage and wear mechanisms of cermet coatings due to their complex structure. This dissertation attempts to address these issues first by taking a systematic step by step approach, process map, to establish a correlation between process, particle state, microstructure and properties. Different strategies were proposed and examined to control the high velocity thermal spray process. This strategy assessment enabled a better control over in-flight particles state in high velocity thermal spray process and provided better understanding on interaction of in-flight particles with the flame. Further, possible advantages of reducing the carbide particle size from micron to nano in terms of mechanical properties and different wear performance were explored. It was suggested that poor wear performance of nano-structured coating is due to presence of brittle phases and less available binder promotes the excessive stress detrimental to load carrying capability of material. Material damage and wear mechanisms of coating under different tribological conditions were examined. The results suggest a

  20. The novel silicon-containing epoxy/PEPA phosphate flame retardant for transparent intumescent fire resistant coating

    NASA Astrophysics Data System (ADS)

    Shi, Yanchao; Wang, Guojian

    2016-11-01

    A series of novel silicon-containing epoxy/PEPA phosphate flame retardants (EPPSi) were synthesized by polyphosphoric acid (PPA), caged bicyclic phosphate 1-oxo-4-hydroxymethyl-2,6,7-trioxa-L-phosphabicyclo [2.2.2] octane (PEPA), and different ratios of silicon-containing epoxy 1,1,3,3-tetramethyl-1,3-bis(3-(oxiran-2-ylmethoxy)propyl)disiloxane (TMSEP) to 1,4-butanediol diglycidyl ether (BDE). The chemical structure of EPPSi was confirmed by Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance spectroscopy (1H NMR). Afterwards, the transparent intumescent fire resistant coatings were prepared by mixing EPPSi and melamine formaldehyde resin. The influence of silicon on the fire protection of coatings was intensively investigated by fire protection test, intumescence ratio, scanning electron microscope (SEM), compressive strength test, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and real-time FTIR. It was found that the fire resistant coatings obtained the best fire protection when the ratio of TMESP/BDE was 20/100, while excessive TMSEP made the fire protection of coatings deceased sharply. The intumescence ratio, compressive strength test and SEM result showed that a synergistic effect existed between phosphorus and silicon, which improved the foam structure and compressive strength of the char layer significantly. XPS result proved the out-migration effect of silicon. The high concentration silicon on surface played an important protecting role for the inner char residue and improved the fire protection of the coatings. TGA result demonstrated that silicon enhanced the thermo-oxidation resistance of coatings efficiently. Furthermore, real-time FTIR revealed the intumescent process of the fire resistant coatings according to the chemical structure changes of char residue.

  1. A doxycycline-loaded polymer-lipid encapsulation matrix coating for the prevention of implant-related osteomyelitis due to doxycycline-resistant methicillin-resistant Staphylococcus aureus.

    PubMed

    Metsemakers, Willem-Jan; Emanuel, Noam; Cohen, Or; Reichart, Malka; Potapova, Inga; Schmid, Tanja; Segal, David; Riool, Martijn; Kwakman, Paulus H S; de Boer, Leonie; de Breij, Anna; Nibbering, Peter H; Richards, R Geoff; Zaat, Sebastian A J; Moriarty, T Fintan

    2015-07-10

    Implant-associated bone infections caused by antibiotic-resistant pathogens pose significant clinical challenges to treating physicians. Prophylactic strategies that act against resistant organisms, such as methicillin-resistant Staphylococcus aureus (MRSA), are urgently required. In the present study, we investigated the efficacy of a biodegradable Polymer-Lipid Encapsulation MatriX (PLEX) loaded with the antibiotic doxycycline as a local prophylactic strategy against implant-associated osteomyelitis. Activity was tested against both a doxycycline-susceptible (doxy(S)) methicillin-susceptible S. aureus (MSSA) as well as a doxycycline-resistant (doxy(R)) methicillin-resistant S. aureus (MRSA). In vitro elution studies revealed that 25% of the doxycycline was released from the PLEX-coated implants within the first day, followed by a 3% release per day up to day 28. The released doxycycline was highly effective against doxy(S) MSSA for at least 14days in vitro. A bolus injection of doxycycline mimicking a one day release from the PLEX-coating reduced, but did not eliminate, mouse subcutaneous implant-associated infection (doxy(S) MSSA). In a rabbit intramedullary nail-related infection model, all rabbits receiving a PLEX-doxycycline-coated nail were culture negative in the doxy(S) MSSA-group and the surrounding bone displayed a normal physiological appearance in both histological sections and radiographs. In the doxy(R) MRSA inoculated rabbits, a statistically significant reduction in the number of culture-positive samples was observed for the PLEX-doxycycline-coated group when compared to the animals that had received an uncoated nail, although the reduction in bacterial burden did not reach statistical significance. In conclusion, the PLEX-doxycycline coating on titanium alloy implants provided complete protection against implant-associated MSSA osteomyelitis, and resulted in a significant reduction in the number of culture positive samples when challenged with a

  2. Polyacrylic acid-coated iron oxide nanoparticles for targeting drug resistance in mycobacteria.

    PubMed

    Padwal, Priyanka; Bandyopadhyaya, Rajdip; Mehra, Sarika

    2014-12-23

    The emergence of drug resistance is a major problem faced in current tuberculosis (TB) therapy, representing a global health concern. Mycobacterium is naturally resistant to most drugs due to export of the latter outside bacterial cells by active efflux pumps, resulting in a low intracellular drug concentration. Thus, development of agents that can enhance the effectiveness of drugs used in TB treatment and bypass the efflux mechanism is crucial. In this study, we present a new nanoparticle-based strategy for enhancing the efficacy of existing drugs. To that end, we have developed poly(acrylic acid) (PAA)-coated iron oxide (magnetite) nanoparticles (PAA-MNPs) as efflux inhibitors and used it together with rifampicin (a first line anti-TB drug) on Mycobacterium smegmatis. PAA-MNPs of mean diameter 9 nm interact with bacterial cells via surface attachment and are then internalized by cells. Although PAA-MNP alone does not inhibit cell growth, treatment of cells with a combination of PAA-MNP and rifampicin exhibits a synergistic 4-fold-higher growth inhibition compared to rifampicin alone. This is because the combination of PAA-MNP and rifampicin results in up to a 3-fold-increased accumulation of rifampicin inside the cells. This enhanced intracellular drug concentration has been explained by real-time transport studies on a common efflux pump substrate, ethidium bromide (EtBr). It is seen that PAA-MNP increases the accumulation of EtBr significantly and also minimizes the EtBr efflux in direct proportion to the PAA-MNP concentration. Our results thus illustrate that the addition of PAA-MNP with rifampicin may bypass the innate drug resistance mechanism of M. smegmatis. This generic strategy is also found to be successful for other anti-TB drugs, such as isoniazid and fluoroquinolones (e.g., norfloxacin), only when stabilized, coated nanoparticles (such as PAA-MNP) are used, not PAA or MNP alone. We hence establish coated nanoparticles as a new class of efflux

  3. Amino acids in Tobamovirus coat protein controlling pepper L(1a) gene-mediated resistance.

    PubMed

    Mizumoto, Hiroyuki; Nakamura, Ikumi; Shimomoto, Yoshifumi; Sawada, Hiromasa; Tomita, Reiko; Sekine, Ken-Taro; Kiba, Akinori; Nishiguchi, Masamichi; Kobayashi, Kappei; Hikichi, Yasufumi

    2012-10-01

    In pepper plants (genus Capsicum), the resistance against Tobamovirus spp. is conferred by L gene alleles. The recently identified L variant L(1a) can recognize coat proteins (CPs) of Tobacco mild green mosaic virus Japanese strain (TMGMV-J) and Paprika mild mottle virus Japanese strain (PaMMV-J), but not of Pepper mild mottle virus (PMMoV), as the elicitor to induce resistance at 24 °C. Interestingly, L(1a) gene-mediated resistance against TMGMV-J, but not PaMMV-J, is retained at 30 °C. This observation led us to speculate that L(1a) can discriminate between CPs of TMGMV-J and PaMMV-J. In this study, we aimed to determine the region(s) in CP by which L(1a) distinguishes TMGMV-J from PaMMV-J. By using chimeric CPs consisting of TMGMV-J and PaMMV-J, we found that the chimeric TMGMV-J CP, whose residues in the β-sheet domain were replaced by those of PaMMV-J, lost its ability to induce L(1a) gene-mediated resistance at 30 °C. In contrast, the chimeric PaMMV-J CP with the β-sheet domain replaced by TMGMV-J CP was able to induce L(1a) gene-mediated resistance at 30 °C. Furthermore, viral particles were not detected in the leaves inoculated with either chimeric virus. These observations indicated that the amino acids within the β-sheet domain were involved in both the induction of L(1a) gene-mediated resistance and virion formation. Further analyses using chimeric CPs of TMGMV-J and PMMoV indicated that amino acids within the β-sheet domain alone were not sufficient for the induction of L(1a) gene-mediated resistance by TMGMV-J CP. These results suggest that multiple regions in Tobamovirus CP are implicated in the induction of L(1a) gene-mediated resistance.

  4. Corrosion resistant coatings for silicon carbide heat exchanger tubes -- Volume 3. Final report

    SciTech Connect

    Boss, D.E.

    1996-06-07

    The development of a silicon carbide (SiC) heat exchanger is a critical step in the development of the Externally-Fired Combined Cycle (EFCC) power system. SiC is the only material that provides the necessary combination of resistance to creep, thermal shock, and oxidation. While the SiC structure materials provide the thermomechanical and thermophysical properties needed for an efficient system, the mechanical properties of the SiC tubes are severely degraded through corrosion by the coal combustion products. To obtain the necessary service life of thousands of hours at temperature, a protective coating is needed that is stable with both the SiC tube and the coal combustion products, resists erosion from the particle laden gas stream, is thermal shock resistant, adheres to SiC during repeated thermal shocks (start-up, process upsets, shut-down), and allows the EFCC system to be cost competitive. This demanding set of technical performance and cost drivers was used in reviewing and selecting candidate protective materials. After a review of open literature, discussion with leading researchers in materials for coal combustion environments, and preliminary thermodynamic studies, a total of ten materials were identified for future study that were grouped into three categories: alumina-based materials, materials stable with SiO{sub 2}, and low expansion materials.

  5. CO2 laser cladding heterogeneous ceramic-metal wear-resistant coatings

    NASA Astrophysics Data System (ADS)

    Fomin, V. M.; Malikov, A. G.; Orishich, A. M.

    2016-10-01

    The microstructure, hardness property and wear resistance of WC, Ni-Cr and Fe powders deposited by laser cladding at varying processing parameters were investigated. The results of the present study revealed the prospects of multilayer cladding of R6M5 high-speed tool steel (analog of M2 steel (USA) and HS6-5-2 steel (EU)) onto low-alloy steel with the use of a laser beam. Controlling thermal cycles of laser cladding, it is possible to obtain a clad coating made of high-speed steel having the structure of high-alloy austenite-martensite mixture with disperse inclusions of carbides up to 10 mm thick, i.e., it is actually possible to create bimetal structures. The wear resistance of the laser-clad self-fluxing PG-10N-01 (Ni-Cr-B-Si-C) alloy increases by a factor of 5 due to addi-tional hardening by cast tungsten carbide (WC) with spherical particles. As a result, it becomes higher than the wear resistance of high-speed steel by more than a factor of 3.

  6. Development and Testing of Abrasion Resistant Hard Coats For Polymer Film Reflectors: Preprint

    SciTech Connect

    Jorgensen, G.; Gee, R.; DiGrazia, M.

    2010-10-01

    Reflective polymer film technology can significantly reduce the cost of solar reflectors and installed Concentrated Solar Power (CSP) plants by both reduced material cost and lower weight. One challenge of polymer reflectors in the CSP environment pertains to contact cleaning methods typically used with glass mirrors. Such contact cleaning methods can scratch the surface of polymer reflectors and thereby reduce specular reflectance. ReflecTech, Inc. (a subsidiary of SkyFuel, Inc.) and the National Renewable Energy Laboratory (NREL) initiated a cooperative research and development agreement (CRADA) to devise and develop an abrasion resistant coating (ARC) suitable for deposition onto polymer based mirror film. A number of candidate ARC products were identified as candidate formulations. Industrial collaborators prepared samples having their ARCs deposited onto ReflecTech Mirror Film pre-laminated to aluminum sheet substrates. Samples were provided for evaluation and subjected to baseline (unweathered) and accelerated exposure conditions and subsequently characterized for abrasion resistance and adhesion. An advanced ARC product has been identified that exhibits outstanding initial abrasion resistance and adhesion to ReflecTech Mirror Film. These properties were also retained after exposure to the various accelerated stress conditions. This material has been successfully manufactured as a 1.5 m wide roll-to-roll construction in a production environment.

  7. Characterization and Evaluation of Cyclic Hot Corrosion Resistance of Detonation-Gun Sprayed Ni-5Al Coatings on Inconel-718

    NASA Astrophysics Data System (ADS)

    Saladi, Sekar; Menghani, Jyoti V.; Prakash, Satya

    2015-06-01

    The high temperature hot corrosion behavior of bare and detonation-gun-sprayed Ni-5Al coatings on Ni-based superalloy Inconel-718 is comparatively discussed in the present study. Hot corrosion studies were carried out at 900 °C for 100 cycles in Na2SO4-60% V2O5 molten salt environment under cyclic heating and cooling conditions. The thermo-gravimetric technique was used to establish the kinetics of hot corrosion. X-ray diffraction, SEM/EDAX, and X-ray mapping techniques were used to analyze the hot corrosion products of bare and coated superalloys. The results indicate that Ni-5Al-coated superalloy showed very good hot corrosion resistance. The overall weight gain and parabolic rate constant of Ni-5Al-coated superalloy were less in comparison with the bare superalloy. The D-gun-sprayed Ni-5Al coating was found to be uniform, adherent, and dense in hot corrosion environment. The formation of nickel- and aluminum-rich oxide scale might have contributed for the better hot corrosion resistance of the coated superalloy.

  8. Functional photocatalytically active and scratch resistant antireflective coating based on TiO2 and SiO2

    NASA Astrophysics Data System (ADS)

    Mazur, M.; Wojcieszak, D.; Kaczmarek, D.; Domaradzki, J.; Song, S.; Gibson, D.; Placido, F.; Mazur, P.; Kalisz, M.; Poniedzialek, A.

    2016-09-01

    Antireflection (AR) multilayer coating, based on combination of five TiO2 and SiO2 thin films, was deposited by microwave assisted reactive magnetron sputtering process on microscope glass substrates. In this work X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy and wettability measurements were used to characterize the structural and surface properties of the deposited coating. These studies revealed that prepared coating was amorphous with low surface roughness. Photocatalytic properties were determined based on phenol decomposition reaction. Measurements of optical properties showed that transmittance in the visible wavelength range was increased after the deposition of AR coating as-compared to bare glass substrate. The mechanical properties were determined on the basis of nano-indentation and scratch resistance tests. Performed research has shown that deposition of an additional thin 10 nm thick TiO2 thin film top layer, the prepared AR coating was photocatalytically active, hydrophobic, scratch resistant and had increased hardness as-compared to bare glass substrate. These results indicate that prepared AR multilayer could be used also as a self-cleaning and protective coating.

  9. Behavior of an improved Zr fuel cladding with oxidation resistant coating under loss-of-coolant accident conditions

    NASA Astrophysics Data System (ADS)

    Park, Dong Jun; Kim, Hyun Gil; Jung, Yang Il; Park, Jung Hwan; Yang, Jae Ho; Koo, Yang Hyun

    2016-12-01

    This study investigates protective coatings for improving the high temperature oxidation resistance of Zr fuel claddings for light water nuclear reactors. FeCrAl alloy and Cr layers were deposited onto Zr plates and tubes using cold spraying. For the FeCrAl/Zr system, a Mo layer was introduced between the FeCrAl coating and the Zr matrix to prevent inter-diffusion at high temperatures. Both the FeCrAl and Cr coatings improved the oxidation resistance compared to that of the uncoated Zr alloy when exposed to a steam environment at 1200 °C. The ballooning behavior and mechanical properties of the coated cladding samples were studied under simulated loss-of-coolant accident conditions. The coated samples showed higher burst temperatures, lower circumferential strain, and smaller rupture openings compared to the uncoated Zr. Although 4-point bend tests of the coated samples showed a small increase in the maximum load, ring compression tests of a sectioned sample showed increased ductility.

  10. Isothermal and cyclic oxidation resistance of boron-modified and germanium-doped silicide coatings for titanium alloys

    SciTech Connect

    Cockeram, B.; Rapp, R.A.

    1996-06-01

    Since titanium alloys with an adequate balance of mechanical properties and high-temperature oxidation resistance have not been developed, protective coatings are required. In the authors previous paper, B-modified and Ge-doped silicide diffusion coatings grown on Cp Ti, Ti-24Al-11Nb, Ti-22Al-27Nb, and Ti-20Al-22Nb by the halide-activated, pack-cementation method were described. In this study, isothermal and cyclic oxidation were used to evaluate the oxidation performance of these coatings in comparison to uncoated substrates. The rate-controlling mechanism for isothermal oxidation at high temperature was solid-state diffusion through a SiO{sub 2} scale, while the mechanism for low-temperature oxidation involved grain-boundary diffusion through TiO{sub 2}. Both isothermal and cyclic oxidation rates for the B-modified and Ge-doped silicide coatings were much slower than for pure TiSi{sub 2}. Oxygen contamination was not detected by microhardness measurements in the coated substrates after 200 oxidation cycles at 500-1000{degrees}C for the Ti-Al-Nb alloys, or at 500-875{degrees}C for Cp Ti. The excellent oxidation resistance for the optimum coating compositions is discussed.

  11. Resistant starch film-coated microparticles for an oral colon-specific polypeptide delivery system and its release behaviors.

    PubMed

    Situ, Wenbei; Chen, Ling; Wang, Xueyu; Li, Xiaoxi

    2014-04-23

    For the delivery of bioactive components to the colon, an oral colon-specific controlled release system coated with a resistant starch-based film through aqueous dispersion coating process was developed. Starch was modified by a high-temperature-pressure reaction, enzymatic debranching, and retrogradation, resulting in a dramatic increase in the resistibility against enzymatic digestion (meaning the formation of resistant starch, specifically RS3). This increase could be associated with an increase in the relative crystallinity, a greater amount of starch molecular aggregation structure, and the formation of a compact mass fractal structure, resulting from the treatment. The microparticles coated with this RS3 film showed an excellent controlled release property. In streptozotocin (STZ)-induced type II diabetic rats, the RS3 film-coated insulin-loaded microparticles exhibited the ability to steadily decrease the plasma glucose level initially and then maintain the plasma glucose level within the normal range for total 14-22 h with different insulin dosages after oral administration; no glycopenia or glycemic fluctuation was observed. Therefore, the potential of this new RS3 film-coated microparticle system has been demonstrated for the accurate delivery of bioactive polypeptides or protein to the colon.

  12. Electro-codeposition of Ni-SiO2 nanocomposite coatings from deep eutectic solvent with improved corrosion resistance

    NASA Astrophysics Data System (ADS)

    Li, Ruiqian; Hou, Yuanyuan; Liang, Jun

    2016-03-01

    Electro-codeposition of nano-sized SiO2 particles into the metal matrix in aqueous solution is generally difficult. In this paper, the nano-sized SiO2 particles were successfully codeposited in the Ni matrix from a choline chloride (ChCl)/ethylene glycol (EG) based deep eutectic solvent (DES) by pulse electro-codeposition. The effects of nano-sized SiO2 particles on electrochemical behaviour of Ni(II) were investigated. The microstructure, composition and corrosion resistance of pure Ni and Ni-SiO2 nanocomposite coatings were explored. Results showed that the SiO2 nanoparticles exhibited excellent dispersion stability in ChCl:2EG DES without any stabilizing additives and the presence of SiO2 nanoparticles have significant effects on the nucleation mechanism of Ni. The maximum content of SiO2 nanoparticles in composite coatings can achieve 4.69 wt.%, which closes to the level of co-deposition micro-sized SiO2 particles from aqueous solution. The Ni-SiO2 nanocomposite coatings exhibit much better corrosion resistance than pure Ni coating, and the corrosion resistance performance increases with increasing SiO2 content in the composite coatings.

  13. Research on microstructure and wear resistance of coatings obtained by adding nanoparticles of refractory compounds in laser cladding

    NASA Astrophysics Data System (ADS)

    Murzakov, M. A.; Chirikov, S. N.; Markushov, Y. V.

    2016-09-01

    The paper is aimed at research of coatings, which are achieved by means of laser cladding with additives of nanoparticles of high-melting compounds in form of tungsten carbide and tantalum (WC and TaC). In the course of experiment, various ceramic powder concentrations were tested. Main technological characteristics were determined. Power density amounted to 0.68-0.98 MW/cm2. During the coating wear resistance measurement, it was discovered that increase in nanopowder concentration extended wear resistance of coating 2-6 times. Wear resistance measurement and wear coefficient calculation were performed using Brinell-Howarth method. The load was 15 N, load time was 10 minutes. Optical metallographic microscope Neophot-30 was used to study microstructure of the deposited coatings. To reveal microstructure of the deposited coatings, the samples were exposed to chemical etching. Elemental composition of the samples was determined by the methods of X- ray microanalysis in testing solution using electron microscope EVO-50 under acceleration voltage 10-20 kV (probe current 5-50 nA) using energy- and wavelength-dispersive spectrometers.

  14. The fabrication, nano/micro-structure, heat- and wear-resistance of the superhydrophobic PPS/PTFE composite coatings.

    PubMed

    Wang, Huaiyuan; Zhao, Jingyan; Zhu, Youzhuang; Meng, Yang; Zhu, Yanji

    2013-07-15

    A simple engineering method was used to fabricate stability and wear-resistance of superhydrophobic PPS-based PPS/PTFE surfaces through nano/micro-structure design and modification of the lowest surface energy groups (-CF2-), which was inspired by the biomimic lotus leaves. The hydrophobic properties and wear-resistance of the coatings were measured by a contact angle meter and evaluated on a pin-on-disk friction and wear tester, respectively. Moreover, the surfaces of the PPS/PTFE composite coatings were investigated by means of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), and thermogravimetry (TG) analysis. Results showed that the highest contact angle of the PPS/PTFE surface, with papillae-like randomly distributed double-scale structure, could reach up to 162°. When 1 wt.% PDMS was added, the highest contact angle could hold is 172°. The coatings also retained superhydrophobicity, even under high temperature environment. The investigation also indicated that the coatings were not only superhydrophobic but also oleophobic behavior at room temperature, such as the crude oil, glycerol, and oil-water mixture. The PPS/45%PTFE coatings had more stable friction coefficient and excellent wear-resistance (331,407 cycles) compared with those with less than 45% of PTFE.

  15. The adhesive strategies of cyprids and development of barnacle-resistant marine coatings.

    PubMed

    Aldred, Nick; Clare, Anthony S

    2008-01-01

    Over the last decade, approaches to the development of surfaces that perturb settlement and/or adhesion by barnacles have diversified substantially. Although, previously, coatings research focussed almost exclusively on biocidal technologies and low modulus, low surface-free-energy 'fouling-release' materials, novel strategies to control surface colonisation are now receiving significant attention. It is timely, therefore, to review the current 'state of knowledge' regarding fouling-resistant surface characteristics and their mechanisms of action against settling larvae of barnacles. The role of the barnacle in marine fouling is discussed here in the context of its life cycle and the behavioural ecology of its cypris larva. The temporary and permanent adhesion mechanisms of cyprids are covered in detail and an overview of adult barnacle adhesion is presented. Recent legislation has directed academic research firmly towards environmentally inert marine coatings, so the actions of traditional biocides on barnacles are not described here. Instead, the discussion is restricted to those surface modifications that interfere with settlement-site selection and adhesion of barnacle cypris larvae; specifically, textural engineering of surfaces, development of inert 'non-fouling' surfaces and the use of enzymes in antifouling.

  16. A novel approach for synthesis of zwitterionic polyurethane coating with protein resistance.

    PubMed

    Wang, Chunhua; Ma, Chunfeng; Mu, Changdao; Lin, Wei

    2014-11-04

    We have developed a novel approach to introduce zwitterions into polyurethane for the preparation of antibiofouling coating. First, the thiol-ene click reaction between 2-(dimethylamino)ethyl methacrylate (DMAEMA) and 3-mercapto-1,2-propanediol (TPG) is used to synthesize dihydroxy-terminated DMAEMA (DMA(OH)2) under UV catalysis. The product has been proved by gel permeation chromatography (GPC), Fourier transform infrared spectrum (FT-IR), proton nuclear magnetic resonance ((1)H NMR), and high resolution mass spectrometry (HRMS). DMA(OH)2 is then incorporated into polyurethane as side groups by polyaddition with diisocyanate and further reacts with 1,3-propane sultone to obtain the zwitterionic polyurethanes. The presence of sulfobetaine zwitterions side groups has been demonstrated by FT-IR and X-ray photoelectron spectroscopy (XPS). Thermal analysis indicates that the thermal stability is decreased with the increasing content of zwitterionions. The antibiofouling property of polyurethanes has been investigated by the measurement of adsorption of fibrinogen, bovine serum albumin (BSA), and lysozyme on the polyurethanes surface using quartz crystal microbalance with dissipation (QCM-D). The results show that the polyurethane coatings exhibit effective nonspecific protein resistance at higher content of zwitterionic side groups.

  17. Study of Corrosion Resistance Improvement by Metallic Coating for Overhead Transmission Line Conductor

    NASA Astrophysics Data System (ADS)

    Isozaki, Masanori; Adachi, Kouichi; Hita, Takanori; Asano, Yuji

    Applying anti-corrosion grease and aluminum clad steel (AC) wires to ACSR has adopted as general methods to prevent overhead transmission line conductors and/or wires from corrosion. However, there are some cases that ineffectiveness of those means are reported on some transmission lines passing through acid atmosphere in the vicinity of a factory exhausting acid smoke. The feature of the corrosion caused by acid atmosphere is to show a higher speed in its progressing as well known. As means against such acid corrosion, application of high purity aluminum, selective removal of inter-metallic compound in aluminum and plastic coating wires has been reported before, and each has both of advantage and disadvantage actually. In the former letter, we reported the new type of anti-corrosion grease that shows an excellent property against acid atmosphere as well as in a salty circumstance. Here presents a new type of anti-corrosion technology of applying high corrosion resistance aluminum alloy or zinc coatings on each component wires of a conductor that we succeed in developing through a serial study of anti-corrosion methods on overhead transmission lines.

  18. Corrosion-resistant amorphous metallic coatings: Engineering development: Progress report, October 1, 1985-October 1, 1986

    SciTech Connect

    Fitzgerald, D.J.; DiStefano, S.; Rameshan, R.

    1986-12-01

    Objective is to use sputter-deposited amorphous metallic coatings on alloys in heat recovery systems in power plants. It was found that chromium could be used as a substitute for ruthenium in MoRuB. The new alloy, MoCrB, has corrosion current two orders of magnitude lower than MoRuB. The effort to develop the parameters for depositing FeCrPC on steel was frustrated by a persistent pinhole problem. Two titanium-based alloys were developed which are equal to or better than the optimized FeCrPC alloy in terms of corrosion resistance. The potentiodynamic polarization characteristics of MoCrB and TiCrBC were measured over a range in temperature from 25 to 100/sup 0/C. The corrosion current increased with temperature as predicted by theory. The corrosion characteristics of MoCrB and TiCrPC were also tested in 1.0N HC1. Cost analysis of the magnetron sputtering coating process indicates that the process cost is in the range of $2.50 to $3.00 per square foot steel.

  19. Influence of alumina and titanium dioxide coatings on abrasive wear resistance of AISI 1045 steel

    NASA Astrophysics Data System (ADS)

    Santos, A.; Remolina, A.; Marulanda, J.

    2016-02-01

    This project aims to compare the behaviour of an AISI 1045 steel's abrasive wear resistance when is covered with aluminium oxide (Al2O3) or Titanium dioxide (TiO2), of nanometric size, using the technique of thermal hot spray, which allows to directly project the suspension particles on the used substrate. The tests are performed based on the ASTM G65-04 standard (Standard Test Method for Measuring Abrasion Using the Dry Sand/Rubber Apparatus). The results show that the amount of, lost material increases linearly with the travelled distance; also determined that the thermal treatment of hardening-tempering and the alumina and titanium dioxide coatings decrease in average a 12.9, 39.6 and 29.3% respectively the volume of released material during abrasive wear test.

  20. Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems

    SciTech Connect

    Gopala N. Krishnan; Ripudaman Malhotra; Esperanza Alvarez; Kai-Hung Lau; Jordi Perez Mariano; Angel Sanjurjo

    2006-09-30

    Heat-exchangers, particle filters, turbines, and other components in integrated coal gasification combined cycle system must withstand the highly sulfiding conditions of the high temperature coal gas over an extended period of time. The performance of components degrades significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low-cost alloy may improve its resistance to such sulfidation attack, and decrease capital and operating costs. The alloys used in the gasifier service include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive nickel-cobalt alloys. The primary activity this period was preparation and presentation of the findings on this project at the Twenty-Third annual Pittsburgh Coal Conference. Dr. Malhotra attended this conference and presented a paper. A copy of his presentation constitutes this quarterly report.

  1. Role of Y in the oxidation resistance of CrAlYN coatings

    NASA Astrophysics Data System (ADS)

    Domínguez-Meister, S.; El Mrabet, S.; Escobar-Galindo, R.; Mariscal, A.; Jiménez de Haro, M. C.; Justo, A.; Brizuela, M.; Rojas, T. C.; Sánchez-López, J. C.

    2015-10-01

    CrAlYN coatings with different aluminum (4-12 at.%) and yttrium (2-5 at.%) contents are deposited by d.c. reactive magnetron sputtering on silicon and M2 steel substrates using metallic targets and Ar/N2 mixtures. The influence of the nanostructure and chemical elemental distribution on the oxidation resistance after heating in air at 1000 °C is studied by means of cross-sectional scanning electron microscopy (X-SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GD-OES). The sequential exposure to the metallic targets during the synthesis leads to a multilayer structure where concentration of metallic elements (Cr, Al and Y) is changing periodically. A good oxidation resistance is observed when Al- and Y-rich regions are separated by well-defined CrN layers, maintaining crystalline coherence along the columnar structure. This protective behavior is independent of the type of substrate and corresponds to the formation of a thin mixed (Al, Cr)-oxide scale that protects the film underneath. The GD-OES and XRD analysis have demonstrated that Y acts as a reactive element, blocking the Fe and C atoms diffusion from the steel and favoring higher Al/Cr ratio in the passivation layer after heating. The coating with Y content around 4 at.% exhibited the best performance with a thinner oxide scale, a delay in the CrN decomposition and transformation to Cr2N, and a more effective Fe and C blocking.

  2. Surface Design and Engineering Toward Wear-Resistant, Self-Lubricant Diamond Films and Coatings. Chapter 10

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1999-01-01

    This chapter describes three studies on the surface design, surface engineering, and tribology of chemical-vapor-deposited (CVD) diamond films and coatings toward wear-resistant, self-lubricating diamond films and coatings. Friction mechanisms and solid lubrication mechanisms of CVD diamond are stated. Effects of an amorphous hydrogenated carbon on CVD diamond, an amorphous, nondiamond carbon surface layer formed on CVD diamond by carbon and nitrogen ion implantation, and a materials combination of cubic boron nitride and CVD diamond on the adhesion, friction, and wear behaviors of CVD diamond in ultrahigh vacuum are described. How surface modification and the selected materials couple improved the tribological functionality of coatings, giving low coefficient of friction and good wear resistance, is explained.

  3. The Influence of Modes of Deposition of Coatings on the Corrosion Resistance of Welded Joints of Steels in Acidic Media;

    NASA Astrophysics Data System (ADS)

    Saraev, Yu N.; Bezborodov, V. P.; Selivanov, Y. V.

    2016-08-01

    In this work, effect of welding on corrosion of welded joints of austenitic steel 12KH18N10T. It is shown that the use of pulsed - arc welding steel 12KH18N10T allows you to create a protective coating with dispersed structure with less thermal impact on the zone of the welded joint. Coating is of such structure allows 1.5 to 6 times to reduce the corrosion rate of welded joints of steel 12KH18N10T in active chemical environments. Pulse the process of deposition of coatings on welded joint of steels can be effectively used for the protection against corrosion in the repair of equipment of chemical industry. The results obtained can be recommended for use when welding a protective corrosion - resistant coatings on working surfaces of equipment of chemical productions.

  4. Size effect of (Al2O3-Y2O3)/YSZ micro-laminated coating on high-temperature oxidation resistance

    NASA Astrophysics Data System (ADS)

    Yao, Junqi; Lv, Lili; He, Yedong; Wang, Deren

    2013-08-01

    The size effect of structure plays an important role in the high-temperature oxidation and spallation resistance of micro-laminated coating on alloy substrate. In this study, (Al2O3-Y2O3)/YSZ micro-laminated coatings with different thickness ratios and layer numbers were prepared on MCrAlY alloy by electrolytic deposition and microwave sintering under pressure. The oxidation and spallation resistance of the micro-laminated coatings were investigated by cyclic oxidation tests in air at 1050 °C for 200 h. Results indicate that both oxidation resistance and spallation resistance of the coating have been improved significantly, by increasing the thickness ratio of YSZ layer to Al2O3-Y2O3 layer and layer number in a specific range. In such micro-laminated coating, increasing the thickness ratio of YSZ layer to Al2O3-Y2O3 layer can improve the apparent thermal expansion coefficient of coating and decrease the thermal stresses. While, increasing the layer number can extend the crack propagation paths and improve the plasticity and fracture toughness. They can improve the mechanical properties of micro-laminated coating and exhibit excellent cracking and spallation resistance. This would give rise to the beneficial effects on suppressing the oxygen inward diffusion and consequently improve the high-temperature oxidation resistance of micro-laminated coating. Such size effect would provide reference values in the structural design of micro-laminated coating in high-temperature application.

  5. Creep resistant, metal-coated LiFeO.sub.2 anodes for molten carbonated fuel cells

    DOEpatents

    Khandkar, Ashok C.

    1994-01-01

    A porous, creep-resistant, metal-coated, LiFeO.sub.2 ceramic electrode for fuel cells is disclosed. The electrode is particularly useful for molten carbonate fuel cells (MCFC) although it may have utilities in solid oxide fuel cells (SOFC) as well.

  6. Creep resistant, metal-coated LiFeO[sub 2] anodes for molten carbonated fuel cells

    DOEpatents

    Khandkar, A.C.

    1994-08-23

    A porous, creep-resistant, metal-coated, LiFeO[sub 2] ceramic electrode for fuel cells is disclosed. The electrode is particularly useful for molten carbonate fuel cells (MCFC) although it may have utilities in solid oxide fuel cells (SOFC) as well. 11 figs.

  7. Erosion resistance of arc-sprayed coatings to iron ore at 25 and 315 °C

    NASA Astrophysics Data System (ADS)

    Dallaire, S.; Levert, H.; Legoux, J.-G.

    2001-06-01

    Iron ore pellets are sintered and reduced in large continuous industrial oil-fired furnaces. From the furnace, powerful fans extract large volumes of hot gas. Being exposed to gas-borne iron ore particles and temperatures ranging between 125 and 328 °C, fan components are rapidly eroded. Extensive part repair or replacement is required for maintaining a profitable operation. The arc spraying technique has been suggested for repair provided it could produce erosion-resistant coatings. Conventional and cored wires (1.6 mm diameter) were arc sprayed using various spray parameters to produce 250 to 300 µm thick coatings. Arc-sprayed coatings and reference specimens were erosion tested at 25 and 315 °C and impact angles of 25 and 90° in a laboratory gas-blast erosion rig. This device was designed to impact materials with coarse (32 to 300 µm) iron ore particles at a speed of 100 m/s. The coating volume loss due to erosion was measured with a laser profilometer built by National Research Council Canada several years ago. Few arc-sprayed coatings exhibited erosion resistance comparable with structural steel at low impact angles. Erosion of arc-sprayed coatings and reference specimens dramatically increases at 315 °C for both 25° and 90° impact angles. Erosion-enhanced oxidation was found to be responsible for the increase in volume loss above room temperature. Though arc spraying can be appropriate for on-site repair, the development of more erosion-resistant coatings is required for intermediate temperatures.

  8. Wear resistance of thick diamond like carbon coatings against polymeric materials used in single screw plasticizing technology

    NASA Astrophysics Data System (ADS)

    Zitzenbacher, G.; Liu, K.; Forsich, C.; Heim, D.

    2015-05-01

    Wear on the screw and barrel surface accompany polymer single screw plasticizing technology from the beginning. In general, wear on screws can be reduced by using nitrided steel surfaces, fused armour alloys on the screw flights and coatings. However, DLC-coatings (Diamond Like Carbon) comprise a number of interesting properties such as a high hardness, a low coefficient of friction and an excellent corrosion resistance due to their amorphous structure. The wear resistance of about 50 µm thick DLC-coatings against polyamide 6.6, polybutylene terephthalate and polypropylene is investigated in this paper. The tribology in the solids conveying zone of a single screw extruder until the beginning of melting is evaluated using a pin on disc tribometer and a so called screw tribometer. The polymeric pins are pressed against coated metal samples using the pin on disc tribometer and the tests are carried out at a defined normal force and sliding velocity. The screw tribometer is used to perform tribological experiments between polymer pellets and rotating coated metal shafts simulating the extruder screw. Long term experiments were performed to evaluate the wear resistance of the DLC-coating. A reduction of the coefficient of friction can be observed after a frictional distance of about 20 kilometers using glass fibre reinforced polymeric materials. This reduction is independent on the polymer and accompanied by a black layer on the wear surface of the polymeric pins. The DLC-coated metal samples show an up to 16 µm deep wear track after the 100 kilometer test period against the glass fiber filled materials only.

  9. Influence of the Spray Gun Type on Microstructure and Properties of HVAF Sprayed Fe-Based Corrosion Resistant Coatings

    NASA Astrophysics Data System (ADS)

    Milanti, A.; Koivuluoto, H.; Vuoristo, P.

    2015-10-01

    The aim of this study is to evaluate the microstructural details and corrosion properties of novel Fe-based coatings prepared using two different generations of HVAF spray guns. These two generations of HVAF guns are Activated Combustion HVAF (AC-HVAF, 2nd generation) M2 gun and Supersonic Air Fuel HVAF (SAF, 3rd generation) M3 gun. Structural details were analysed using x-ray diffractometry and field-emission scanning electron microscope. Higher denseness with homogeneous microstructure was achieved for Fe-based coating deposited by the M3 process. Such coatings exhibit higher particle deformation and lower oxide content compared to coatings manufactured with M2 gun. Corrosion properties were studied by open-cell potential measurements and electrochemical impedance spectroscopy. The lower porosity and higher interlamellar cohesion of coating manufactured with M3 gun prevent the electrolyte from penetrating through the coating and arriving to the substrate, enhancing the overall corrosion resistance. This can be explained by the improved microstructures and coating performance.

  10. Silver-Containing Hydroxyapatite Coating Reduces Biofilm Formation by Methicillin-Resistant Staphylococcus aureus In Vitro and In Vivo

    PubMed Central

    Miyamoto, Hiroshi; Shobuike, Takeo; Kobatake, Tomoki; Mawatari, Masaaki

    2016-01-01

    Biofilm-producing bacteria are the principal causes of infections associated with orthopaedic implants. We previously reported that silver-containing hydroxyapatite (Ag-HA) coatings exhibit high antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). In the present study, we evaluated the effects of Ag-HA coating of implant surfaces on biofilm formation. Titanium disks (14-mm diameter, 1-mm thickness), one surface of which was coated with HA or 0.5%–3.0% Ag-HA with a thermal spraying technique, were used. In vitro, the disks were inoculated with an MRSA suspension containing 4 × 105 CFU and incubated for 1-2 weeks. In vivo, MRSA-inoculated HA and 3% Ag-HA disks (8.8–10.0 × 108 CFU) were implanted subcutaneously on the back of rats for 1–7 days. All disks were subsequently stained with a biofilm dye and observed under a fluorescence microscope, and biofilm coverage rates (BCRs) were calculated. The BCRs on the Ag-HA coating were significantly lower than those on the HA coating at all time points in vitro (p < 0.05). Similar results were observed in vivo (p < 0.001) without argyria. Ag-HA coating reduced biofilm formation by MRSA in vitro and in vivo; therefore, Ag-HA coating might be effective for reducing implant-associated infections. PMID:28105433

  11. High temperature corrosion-resistant protective coatings in stationary gas turbines

    NASA Technical Reports Server (NTRS)

    Gruenling, H. W.

    1977-01-01

    Methods currently used to deposit protective coatings in gas turbines are reviewed, and the structure of the respective coatings is examined. The corrosion behavior of such coatings is discussed on the basis of experimental data. General trends in the preparation of protective coatings are noted.

  12. Development of Silica Glass Coatings on 316L SS and Evaluation of its Corrosion Resistance Behavior in Ringer's Solution

    NASA Astrophysics Data System (ADS)

    Vijayalakshmi, U.; Rajeswari, S.

    2012-12-01

    Sol-gel derived silica glasses have many promising features, including low-temperature preparation as well as chemical and physical stability. Two silica glasses with Si100 and Si80 composition were prepared to understand the factors contributing to the rate of bioactivity. The effects of pH, solution aging temperature, and molar ratio of H2O/tetraethyl orthosilicate (TEOS) were studied, and the obtained powder sample was characterized by Fourier transform infrared spectroscopy, X-ray diffraction studies, and scanning electron microscopy. The synthesized silica glasses were deposited on 316L SS by the spin coating method at the optimized speed of 2000 revolutions per minute. The corrosion resistance behavior of the coatings was determined by (1) open-circuit potential vs time of exposure, (2) electrochemical impedance spectroscopy, and (3) cyclic polarization in Ringer's solution. A higher breakdown potential ( E b) and repassivation potential ( E p) value with lower current density was obtained from cyclic polarization. Similar results were observed from impedance analysis with higher charge transfer resistance ( R ct) and lower double layer capacitance ( C dl) indicating the corrosion resistance behavior of the coatings compared with the uncoated 316L stainless steel. From the results, it was observed that both Si100 and Si80 glass coatings had a positive effect on the corrosion resistance behavior. An adhesive strength of 46 MPa and 45 MPa was obtained for the Si100 and Si80 coatings, respectively. An accelerated leach out study was carried out by impressing the potential at their breakdown potential to determine the effect of glass coating for long-term contact between the implant and a normal biological medium.

  13. Corrosion resistance of enamel coating modified by calcium silicate and sand particle for steel reinforcement in concrete

    NASA Astrophysics Data System (ADS)

    Tang, Fujian

    Porcelain enamel has stable chemical property in harsh environments such as high temperature, acid and alkaline, and it can also chemically react with substrate reinforcing steel resulting in improved adherence strength. In this study, the corrosion resistances of enamel coating modified by calcium silicate and sand particles, which are designed for improved bond strength with surrounding concrete, were investigated in 3.5 wt% NaCl solution. It consists of two papers that describe the results of the study. The first paper investigates the corrosion behavior of enamel coating modified by calcium silicate applied to reinforcing steel bar in 3.5 wt% NaCl solution by OCP, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The coatings include a pure enamel, a mixed enamel that consists of 50% pure enamel and 50% calcium silicate by weight, and a double enamel that has an inner pure enamel layer and an outer mixed enamel layer. Electrochemical tests demonstrates that both pure and double enamel coatings can significantly improve corrosion resistance, while the mixed enamel coating offers very little protection due to connected channels. The second paper is focused on the electrochemical characteristics of enamel coating modified by sand particle applied to reinforcing steel bar in 3.5 wt% NaCl solution by EIS. Six percentages by weight are considered including 5%, 10%, 20%, 30%, 50%, and 70%. Results reveal that addition of sand particle does not affect its corrosion resistance significantly. Most of the sand particles can wet very well with enamel body, while some have a weak zone which is induced during the cooling stage due to different coefficient of thermal expansion. Therefore, quality control of sand particle is the key factor to improve its corrosion resistance.

  14. Analysis of the Effect of Surface Modification on Polyimide Composites Coated with Erosion Resistant Materials

    NASA Technical Reports Server (NTRS)

    Ndalama, Tchinga; Hirschfeld, Deidre; Sutter, James K. (Technical Monitor)

    2003-01-01

    The aim of this research is to enhance performance of composite coatings through modification of graphite-reinforced polyimide composite surfaces prior to metal bond coat/ hard topcoat application for use in the erosive and/or oxidative environments of advanced engines. Graphite reinforced polyimide composites, PMR-15 and PMR-II-50, formed by sheet molding and pre-pregging will be surface treated, overlaid with a bond coat and then coated with WC-Co. The surface treatment will include cleaning, RF plasma or ultraviolet light- ozone etching, and deposition of SiO(x) groups. These surface treatments will be studied in order to investigate and improve adhesion and oxidation resistance. The following panels were provided by NASA-Glenn Research Center(NASA-GRC): Eight compression molded PMR-II-50; 6 x 6 x 0.125 in. Two vacuum-bagged PMR-II-50; 12 x 12 x 0.125 in. Eight compression molded PMR-15; 6 x 6 x 0.125 in. One vacuum-bagged PMR-15; 12 x 12 x 0.125 in. All panels were made using a 12 x 12 in. T650-35 8HS (3K-tow) graphite fabric. A diamond-wafering blade, with deionized water as a cutting fluid, was used to cut PMR-II-50 and PMR-15 panels into 1 x 1 in. pieces for surface tests. The panel edges exhibiting delamination were used for the preliminary surface preparation tests as these would be unsuitable for strength and erosion testing. PMR-15 neat resin samples were also provided by NASA GRC. Surface profiles of the as-received samples were determined using a Dektak III Surface profile measuring system. Two samples of compression molded PMR-II-50 and PMR-15, vacuum-bagged PMR-II-50 and PMR-15 were randomly chosen for surface profile measurement according to ANSI/ASME B46.1. Prior to each measurement, the samples were blasted with compressed air to remove any artifacts. Five 10 mm-long scans were made on each sample. The short and long wavelength cutoff filter values were set at 100 and 1000 m, diamond stylus radius was 12.5 microns. Table 1 is a summary of the

  15. Thermal barrier coatings for thermal insulation and corrosion resistance in industrial gas turbine engines

    NASA Technical Reports Server (NTRS)

    Vogan, J. W.; Hsu, L.; Stetson, A. R.

    1981-01-01

    Four thermal barrier coatings were subjected to a 500-hour gas turbine engine test. The coatings were two yttria stabilized zirconias, calcium ortho silicate and calcium meta titanate. The calcium silicate coating exhibited significant spalling. Yttria stabilized zirconia and calcium titanate coatings showed little degradation except in blade leading edge areas. Post-test examination showed variations in the coating due to manual application techniques. Improved process control is required if engineering quality coatings are to be developed. The results indicate that some leading edge loss of the coating can be expected near the tip.

  16. Environmental degradation of oxidation resistant and thermal barrier coatings for fuel-flexible gas turbine applications

    NASA Astrophysics Data System (ADS)

    Mohan, Prabhakar

    The development of thermal barrier coatings (TBCs) has been undoubtedly the most critical advancement in materials technology for modern gas turbine engines. TBCs are widely used in gas turbine engines for both power-generation and propulsion applications. Metallic oxidation-resistant coatings (ORCs) are also widely employed as a stand-alone protective coating or bond coat for TBCs in many high-temperature applications. Among the widely studied durability issues in these high-temperature protective coatings, one critical challenge that received greater attention in recent years is their resistance to high-temperature degradation due to corrosive deposits arising from fuel impurities and CMAS (calcium-magnesium-alumino-silicate) sand deposits from air ingestion. The presence of vanadium, sulfur, phosphorus, sodium and calcium impurities in alternative fuels warrants a clear understanding of high-temperature materials degradation for the development of fuel-flexible gas turbine engines. Degradation due to CMAS is a critical problem for gas turbine components operating in a dust-laden environment. In this study, high-temperature degradation due to aggressive deposits such as V2O5, P2O 5, Na2SO4, NaVO3, CaSO4 and a laboratory-synthesized CMAS sand for free-standing air plasma sprayed (APS) yttria stabilized zirconia (YSZ), the topcoat of the TBC system, and APS CoNiCrAlY, the bond coat of the TBC system or a stand-alone ORC, is examined. Phase transformations and microstructural development were examined by using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. This study demonstrated that the V2O5 melt degrades the APS YSZ through the formation of ZrV2O7 and YVO 4 at temperatures below 747°C and above 747°C, respectively. Formation of YVO4 leads to the depletion of the Y2O 3 stabilizer and the deleterious transformation of the YSZ to the monoclinic ZrO2 phase. The investigation on the YSZ degradation by Na 2SO4 and a Na2SO4 + V2

  17. Formation Wear Resistant Coatings on Martensite Steel Hardox 450 by Welding Methods

    NASA Astrophysics Data System (ADS)

    Konovalov, S. V.; Kormyshev, V. E.; Nevskii, S. A.; Ivanov, Yu F.; Gromov, V. E.

    2016-08-01

    By methods of modern physical materials science the investigations analysis of phase composition, defect substructure, mechanical and tribological properties of Cr-Nb-C-V containing coatings formed in surfacing on martensitic wear resistant steel Hardox 450 were carried out. It was shown that surfacing resulted in the formation of high strength surface layer 6 mm in thinness. This layer had wear resistance 138 times greater than that of the base and friction coefficient 2.5 times less. Having analyzed the deflected mode of the deposited material in conditions of friction, a conclusion is drawn that plastic shear deformation is localized in the surface layer due to the high friction factor, as the result, scratches are formed. The maximum of tangential stress is deflected deep into the material provided that friction factor is low. On the basis of the investigations by methods of X-ray structural analysis and transmission diffraction electron microscopy it was shown that increase strength and tribological properties of surfacing metal were caused by its phase composition and state of defect substructure, namely, availability of interstitial phases (more than 36%) and martensitic type of a-phase structure.

  18. Microstructure and Wear Resistance of Chromium Carbide Coating IN SITU Synthesized by VEB

    NASA Astrophysics Data System (ADS)

    Lu, Binfeng; Li, Liping; Lu, Fenggui; Tang, Xinhua

    2014-08-01

    In this paper, (Cr, Fe)7C3(M7C3)/γ-Fe composite layer has been in situ fabricated on a low carbon steel surface by vacuum electron beam irradiation (VEB). Three kinds of powder mixtures were placed on a low carbon steel substrate, which was then irradiated with electron beam in vacuum condition. The microstructure and wear resistance of the composite layers has been studied by means of optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM), microhardness tester and tribological tester. The chemical composition of all specimens were carefully analyzed using energy-dispersive X-ray spectroscopy (EDAX) technique. Depending on three different powder mixtures, hypereutectic and hypoeutectic microstructures were obtained on surface composite layers. No pores and cracks were found on the coatings. The amount of carbides formed in the surface composite layer was mainly determined by carbon concentration. The microstructure close to the fusion line was largely primary austenite dendrite. The hardness and wear resistance of the surface composite layer has been greatly improved due to the extensive distribution of carbides.

  19. Roughening of porous SiCOH materials in fluorocarbon plasmas

    NASA Astrophysics Data System (ADS)

    Bailly, F.; David, T.; Chevolleau, T.; Darnon, M.; Posseme, N.; Bouyssou, R.; Ducote, J.; Joubert, O.; Cardinaud, C.

    2010-07-01

    Porous SiCOH materials integration for integrated circuits faces serious challenges such as roughening during the etch process. In this study, atomic force microscopy is used to investigate the kinetics of SiCOH materials roughening when they are etched in fluorocarbon plasmas. We show that the root mean square roughness and the correlation length linearly increase with the etched depth, after an initiation period. We propose that: (1) during the first few seconds of the etch process, the surface of porous SiCOH materials gets denser. (2) Cracks are formed, leading to the formation of deep and narrow pits. (3) Plasma radicals diffuse through those pits and the pore network and modify the porous material at the bottom of the pits. (4) The difference in material density and composition between the surface and the bottom of the pits leads to a difference in etch rate and an amplification of the roughness. In addition to this intrinsic roughening mechanism, the presence of a metallic mask (titanium nitride) can lead to an extrinsic roughening mechanism, such as micromasking caused by metallic particles originating form the titanium nitride mask.

  20. Investigations of the environmental acceptability of fluorocarbon alternatives to chlorofluorocarbons.

    PubMed

    McFarland, M

    1992-02-01

    Chlorofluorocarbons (CFCs) are currently used in systems for preservation of perishable foods and medical supplies, increasing worker productivity and consumer comfort, conserving energy and increasing product reliability. As use of CFCs is phased out due to concerns of ozone depletion, a variety of new chemicals and technologies will be needed to serve these needs. In choosing alternatives, industry must balance concerns over safety and environmental acceptability and still meet the preformance characteristics of the current technology, the only viable alternatives meeting the safety, performance, and environmental requirements for the remaining 40% of demand are fluorocarbons, hydrochlorofluorocarbons (HCFs), and hydrofluorocarbons (HFCs). HCFCs and HFCs possess many of the desirable properties of the CFCs, but because of the, hydrogen, they results in shorter atmospheric lifetimes compared to CFCs and reduces their potential to contribute to stratospheric ozone depletion or global warming; HFCs do not contain chlorine and have no potential to destroy ozone. This paper provides an overview of challenges faced by industry, regulators, and society in general in continuing to meet societal needs and consumer demands while reducing risk to the enviroment without compromising consumer or worker safety.

  1. Effect of tetrahedral amorphous carbon coating on the resistivity and wear of single-walled carbon nanotube network

    NASA Astrophysics Data System (ADS)

    Iyer, Ajai; Kaskela, Antti; Novikov, Serguei; Etula, Jarkko; Liu, Xuwen; Kauppinen, Esko I.; Koskinen, Jari

    2016-05-01

    Single walled carbon nanotube networks (SWCNTNs) were coated by tetrahedral amorphous carbon (ta-C) to improve the mechanical wear properties of the composite film. The ta-C deposition was performed by using pulsed filtered cathodic vacuum arc method resulting in the generation of C+ ions in the energy range of 40-60 eV which coalesce to form a ta-C film. The primary disadvantage of this process is a significant increase in the electrical resistance of the SWCNTN post coating. The increase in the SWCNTN resistance is attributed primarily to the intrinsic stress of the ta-C coating which affects the inter-bundle junction resistance between the SWCNTN bundles. E-beam evaporated carbon was deposited on the SWCNTNs prior to the ta-C deposition in order to protect the SWCNTN from the intrinsic stress of the ta-C film. The causes of changes in electrical resistance and the effect of evaporated carbon thickness on the changes in electrical resistance and mechanical wear properties have been studied.

  2. Effect of primer composition on cathodic disbonding resistance and adhesion durability of three layer polyethylene coated steel pipe

    SciTech Connect

    Tsuri, S.; Takao, K.; Mochizuki, K.

    1998-12-31

    The cathodic disbonding resistance and adhesion durability of three layer polyethylene coated steel pipe were studied from the viewpoint of water permeability and the water uptake of dicyandiamide-imidazole cured epoxy primer. The reaction between the epoxy resin and dicyandiamide generates hydroxyl groups. Therefore, as the content of dicyandiamide increased, the water uptake of the primer increased and the water diffusion rate of the primer decreased because of the strong interaction between hydroxyl reaction product and water molecules. Excellent cathodic disbonding resistance and adhesion durability were observed when the primer had the lowest water permeability which was expressed as the product of the water uptake and water diffusion rate. On the other hand, the addition of a corrosion protective pigment to the primer improved cathodic disbonding resistance and adhesion durability when the primer had high water uptake, which secured the sufficient solubility of the pigment. Polyethylene coated steel pipes are often used as pipelines for oil and natural gas.

  3. Effect of Sealing Treatment on Corrosion Resistance of Plasma-Sprayed NiCrAl/Cr2O3-8 wt.%TiO2 Coating

    NASA Astrophysics Data System (ADS)

    Zhang, Jingjing; Wang, Zehua; Lin, Pinghua; Lu, Wenhuan; Zhou, Zehua; Jiang, Shaoqun

    2011-03-01

    Plasma-sprayed ceramic coatings inherently contain pores and micro-cracks which is deleterious when performed in aggressive environment. Various methods were applied to the as-sprayed coatings in order to improve the corrosion resistance. In the investigation of this study, plasma-sprayed NiCrAl/Cr2O3-8 wt.%TiO2 coatings were sealed by epoxy resin and silicone resin, respectively. Coatings were characterized by scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), optical microscopy (OM) and x-ray diffraction (XRD). The possible corrosion mechanism was discussed. The results of salt spray test and electrochemical measurements indicated that after the sealing treatment, the porosity of coatings decreased obviously and a compact layer was formed to protect the coating from corrosion. The silicone resin proved to be more effective than epoxy resin in enhancing the corrosion resistance of the coatings used in this research.

  4. Highly Bactericidal Polyurethane Effective Against Both Normal and Drug-Resistant Bacteria: Potential Use as an Air Filter Coating.

    PubMed

    Taylor, Matthew; McCollister, Bruce; Park, Daewon

    2016-03-01

    The battle against the prevalence of hospital-acquired infections has underscored the importance of identifying and maintaining the cleanliness of possible infection transmission sources in the patient's environment. One of the most crucial lines of defense for mitigating the spread of pathogens in a healthcare facility is the removal of microorganisms from the environment by air filtration systems. After removing the pathogenic microorganisms, the filters used in these systems can serve as reservoirs for the pathogens and pose a risk for secondary infection. This threat, combined with the ever-growing prevalence of drug-resistant bacterial strains, substantiates the need for an effective bactericidal air filter. To this end, a broad-spectrum bactericidal polyurethane incorporating immobilized quaternary ammonium groups was developed for use as an air filter coating. In this study, the bactericidal activity of the polymer coating on high-efficiency particulate air (HEPA) filter samples was quantified against eight bacterial strains commonly responsible for nosocomial infection-including drug-resistant strains, and confirmed when applied as a filter coating in conditions mimicking those of its intended application. The coated HEPA filter samples exhibited high bactericidal activity against all eight strains, and the polyurethane was concluded to be an effective coating in rendering HEPA filters bactericidal.

  5. Corrosion resistant nickel superalloy coatings laser-clad with a 6 kW high power diode laser (HPDL)

    NASA Astrophysics Data System (ADS)

    Tuominen, Jari; Honkanen, Mari; Hovikorpi, Jari; Vihinen, Jorma; Vuoristo, Petri; Maentylae, Tapio

    2003-03-01

    A series of exerpiments were performed to investigate the one-step laser cladding of Inconel 625 powder, injected off-axially onto Fe37 and 42CrMo4 substrates. The experiments were carried out using a 6 kW high power diode laser (HPDL) mounted to a 6 axis robot system. The rectangular shape of the delivering beam was focused to a spot size of 22 x 5 mm on the work piece. The coating samples were produced using different levels of powder feed rate (77 - 113 g/min), traveling speed (300 - 400 mm/min) and laser power (4.8 - 6 kW). Hot corrosion resistance of laser-clad Inconel 625 coatings were tested in Na2SO4 - V2O5 at 650°C for 1000 hours. Wet corrosion properties of the obtained coatings were tested in immersion tests in 3.5 wt.% NaCl solution. Diode laser power of 6 kW (808 and 940 nm) was high enough to produce 20 mm wide laser-clad tracks with a thickness of 2.5 mm in a single pass, when powder feed rate was more than 6 kg/h and traverse speed was 400 mm/min. Wet corrosion properties of laser-clad Inconel 625 coatings were found to be superior to sprayed and welded coatings. Hot corrosion resistance was even slightly better than corresponding wrought alloy. Finally, one-step HPDL cladding was demonstrated in coating of shaft for hydraulic cylinder with Inconel 625 powder. Due to high coating quality, high deposition rate and traverse speed HPDL devices are very promising for large area cladding applications.

  6. Resistance of Coated and Uncoated IR Windows to Seawater Corrosion. Phase V. Summary

    DTIC Science & Technology

    1981-02-01

    competitive substrate materials, uncoated; single-layer AR coatings on germanium and zinc selenide; multiple-layer AR coatings on germanium; overcoatings on...testing) whose plastic coating has torn and peeled away from the substrate , leaving the substrate exposed to corrosion by seawater... 21 12. A coated...II examined two substrate materials (germanium and chalcogenide glass), and antifouling methods such as forced seawater circulation and electric

  7. Oxidation-resistant coatings for refractory metals used in inert atmospheres

    NASA Technical Reports Server (NTRS)

    Phillips, W. M.

    1970-01-01

    Test conditions and results are reported for various coatings on a 1 percent zirconium columbium alloy at a temperature of 2000 deg F. Molybdenum silicide over molybdenum is most effective coating, tin-aluminum coating is adequately protective, chromium-molybdenum silicides are not protective.

  8. Nanostructures in water-in-CO2 microemulsions stabilized by double-chain fluorocarbon solubilizers.

    PubMed

    Sagisaka, Masanobu; Iwama, Shuho; Ono, Shinji; Yoshizawa, Atsushi; Mohamed, Azmi; Cummings, Stephen; Yan, Ci; James, Craig; Rogers, Sarah E; Heenan, Richard K; Eastoe, Julian

    2013-06-25

    High-pressure small-angle neutron scattering (HP-SANS) studies were conducted to investigate nanostructures and interfacial properties of water-in-supercritical CO2 (W/CO2) microemulsions with double-fluorocarbon-tail anionic surfactants, having different fluorocarbon chain lengths and linking groups (glutarate or succinate). At constant pressure and temperature, the microemulsion aqueous cores were found to swell with an increase in water-to-surfactant ratio, W0, until their solubilizing capacities were reached. Surfactants with fluorocarbon chain lengths of n = 4, 6, and 8 formed spherical reversed micelles in supercritical CO2 even at W0 over the solubilizing powers as determined by phase behavior studies, suggesting formation of Winsor-IV W/CO2 microemulsions and then Winsor-II W/CO2 microemulsions. On the other hand, a short C2 chain fluorocarbon surfactant analogue displayed a transition from Winsor-IV microemulsions to lamellar liquid crystals at W0 = 25. Critical packing parameters and aggregation numbers were calculated by using area per headgroup, shell thickness, the core/shell radii determined from SANS data analysis: these parameters were used to help understand differences in aggregation behavior and solubilizing power in CO2. Increasing the microemulsion water loading led the critical packing parameter to decrease to ~1.3 and the aggregation number to increase to >90. Although these parameters were comparable between glutarate and succinate surfactants with the same fluorocarbon chain, decreasing the fluorocarbon chain length n reduced the critical packing parameter. At the same time, reducing chain length to 2 reduced negative interfacial curvature, favoring planar structures, as demonstrated by generation of lamellar liquid crystal phases.

  9. Development of wear-resistant ceramic coatings for diesel engine components. Volume 1, Coating development and tribological testing: Final report: DOE/ORNL Ceramic Technology Project

    SciTech Connect

    Naylor, M.G.S.

    1992-06-01

    The tribological properties of a variety of advanced coating materials have been evaluated under conditions which simulate the piston ring -- cylinder liner environment near top ring reversal in a heavy duty diesel engine. Coated ``ring`` samples were tested against a conventional pearlitic grey cast iron liner material using a high temperature reciprocating wear test rig. Tests were run with a fresh CE/SF 15W40lubricant at 200 and 350{degrees}C, with a high-soot, engine-tested oil at 200{degrees}C and with no lubrication at 200{degrees}C. For lowest wear under boundary lubricated conditions, the most promising candidates to emerge from this study were high velocity oxy-fuel (HVOF) Cr{sub 3} C{sub 2} - 20% NiCr and WC - 12% Co cermets, low temperature arc vapor deposited (LTAVD) CrN and plasma sprayed chromium oxides. Also,plasma sprayed Cr{sub 2}O{sub 3} and A1{sub 2}O{sub 3}-ZrO{sub 2} materials were found to give excellent wear resistance in unlubricated tests and at extremely high temperatures (450{degrees}C) with a syntheticoil. All of these materials would offer substantial wear reductions compared to the conventional electroplated hard chromium ring facing and thermally sprayed metallic coatings, especially at high temperatures and with high-soot oils subjected to degradation in diesel environments. The LTAVD CrN coating provided the lowest lubricated wear rates of all the materials evaluated, but may be too thin (4 {mu}m) for use as a top ring facing. Most of the coatings evaluated showed higher wear rates with high-soot, engine-tested oil than with fresh oil, with increases of more than a factor of ten in some cases. Generally, metallic materials were found to be much more sensitive to soot/oil degradation than ceramic and cermet coatings. Thus, decreased ``soot sensitivity`` is a significant driving force for utilizing ceramic or cermet coatings in diesel engine wear applications.

  10. Electron attachment and positive ion chemistry of monohydrogenated fluorocarbon radicals

    SciTech Connect

    Wiens, Justin P.; Shuman, Nicholas S.; Miller, Thomas M.; Viggiano, Albert A.

    2015-08-21

    Rate coefficients and product branching fractions for electron attachment and for reaction with Ar{sup +} are measured over the temperature range 300–585 K for three monohydrogenated fluorocarbon (HFC) radicals (CF{sub 3}CHF, CHF{sub 2}CF{sub 2}, and CF{sub 3}CHFCF{sub 2}), as well as their five closed-shell precursors (1-HC{sub 2}F{sub 4}I, 2-HC{sub 2}F{sub 4}I, 2-HC{sub 2}F{sub 4}Br, 1-HC{sub 3}F{sub 6}I, 2-HC{sub 3}F{sub 6}Br). Attachment to the HFC radicals is always fairly inefficient (between 0.1% and 10% of the Vogt–Wannier capture rate), but generally faster than attachment to analogous perfluorinated carbon radicals. The primary products in all cases are HF-loss to yield C{sub n}F{sub m−1}{sup −} anions, with only a minor branching to F{sup −} product. In all cases the temperature dependences are weak. Attachment to the precursor halocarbons is near the capture rate with a slight negative temperature dependence in all cases except for 2-HC{sub 2}F{sub 4}Br, which is ∼10% efficient at 300 K and becomes more efficient, approaching the capture rate at higher temperatures. All attachment kinetics are successfully reproduced using a kinetic modeling approach. Reaction of the HFC radicals with Ar{sup +} proceeds at or near the calculated collisional rate coefficient in all cases, yielding a wide variety of product ions.

  11. Development of a special purpose spacecraft interior coating, phase 3

    NASA Technical Reports Server (NTRS)

    Gillman, H. D.; Nannelli, P.

    1979-01-01

    A variety of intumescent coatings based on a fluorocarbon latex resin modified with either an acrylic resin or an epoxy resin were prepared. Several intumescent systems were used for these studies including some based on ammonium polyphosphate and others based on sulfanilamide. The best coatings developed had a high concentration (60-70% by wt.) of intumescent additives and had to be applied thick, approximately 100 mils, in order to have adequate intumescent/fire protection properties.

  12. Development of Erosion-Corrosion-Resistant Cold-Spray Nanostructured Ni-20Cr Coating for Coal-Fired Boiler Applications

    NASA Astrophysics Data System (ADS)

    Kumar, M.; Singh, H.; Singh, N.; Chavan, N. M.; Kumar, S.; Joshi, S. V.

    2015-12-01

    The erosion-corrosion (E-C) behavior of a cold-spray nanostructured Ni-20Cr coating was studied under cyclic conditions in a coal-fired boiler. This study was done for 15 cycles (1500 h), in which each cycle comprised 100 h of heating in the boiler environment, followed by 1 h of cooling under ambient air conditions. The E-C extent was evaluated in terms of thickness loss data of the samples. The eroded-corroded samples were characterized using XRD, SEM/EDS, and x-ray mapping analyses. The nanostructured coating offered excellent E-C protection to boiler tube material (SA 516 steel) under harsh live conditions of the boiler. This E-C resistance offered by investigated coating may be attributed to the presence of protective NiO and Cr2O3 phases in its oxide scale and its superior as-sprayed microhardness.

  13. Corrosion resistant coatings. (Latest citations from the EI compendex*plus database). Published Search

    SciTech Connect

    1995-01-01

    The bibliography contains citations concerning the anticorrosive behavior of protective coatings based on such materials as ceramics, metals, and polymers. Topics include high and low temperature corrosion, surface structure, mechanical and chemical properties, applications, and performance evaluations. Paints and powder coatings, and methods of application are also considered. Protective coatings for specific applications such as gas turbines, coal gasification, power plants, papermaking, carbon steels, reinforced concrete, pipelines, antifouling coatings, and conversion coatings are examined in separate bibliographies. (Contains 250 citations and includes a subject term index and title list.)

  14. Biocompatibly Coated 304 Stainless Steel as Superior Corrosion-Resistant Implant Material to 316L Steel

    NASA Astrophysics Data System (ADS)

    Paul, Subir; Mandal, Chandranath

    2013-10-01

    Surface treatments of 304 stainless steel by electro-coating and passivating in few inorganic electrolytes were found to be very effective in drastically reducing the corrosion rate of the material in stimulated body fluid (SBF) by several orders in comparison to that of 316L steel, presently being used for orthopedic implants. Polarization studies of electrodeposited hydroxyl apatite coating on 304 steel showed remarkably improved corrosion current. Cyclic polarization of the material in SBF reflected the broadened passivity region, much lower passive current, and narrower hysteresis loops. Similar effects were also found through the formation of inorganic coatings by passivation in NaF, CaNO3, and calcium phosphate buffer solutions. Surface characterization by XRD showed the peaks of the respective coating crystals. The morphology of the coatings studied by SEM showed a flake-type structure for hydroxyapatite coating and fine spherical-subspherical particles for other coatings.

  15. Particle-Induced X-Ray Emission (PIXE) Of Silicate Coatings On High Impact Resistance Polycarbonates

    NASA Astrophysics Data System (ADS)

    Xing, Qian; Hart, M. A.; Culbertson, R. J.; Bradley, J. D.; Herbots, N.; Wilkens, Barry J.; Sell, David A.; Watson, Clarizza Fiel

    2011-06-01

    Particle-Induced X-ray Emission (PIXE) analysis was employed to characterize hydroxypropyl methylcellulose (HPMC) C32H60O19 polymer film via areal density measurement on silicon-based substrates utilizing the differential PIXE concept, and compared with Rutherford backscattering spectrometry (RBS) results. It is demonstrated in this paper that PIXE and RBS measurements both yield comparable results for areal densities ranging from 1018 atom/cm2 to several 1019 atom/cm2. A collection of techniques including PIXE, RBS, tapping mode atomic force microscopy (TMAFM), and contact angle analysis were used to compute surface free energy, analyze surface topography and roughness parameters, determine surface composition and areal density, and to predict the water affinity and condensation behaviors of silicates and other compounds used for high impact resistance vision ware coatings. The visor surface under study is slightly hydrophilic, with root mean square of surface roughness on the order of one nm, and surface wavelength between 200 nm and 300 nm. Water condensation can be controlled on such surfaces via polymers adsorption. HPMC polymer areal density measurement supports the analysis of the surface water affinity and topography and the subsequent control of condensation behavior. HPMC film between 1018 atom/cm2 and 1019 atom/cm2 was found to effectively alter the water condensation pattern and prevents fogging by forming a wetting layer during condensation.

  16. Electromagnetic property of SiO2-coated carbonyl iron/polyimide composites as heat resistant microwave absorbing materials

    NASA Astrophysics Data System (ADS)

    Wang, Hongyu; Zhu, Dongmei; Zhou, Wancheng; Luo, Fa

    2015-02-01

    Heat resistant microwave absorbing materials were prepared by compression molding method, using polyimide resin as matrix and SiO2 coated carbonyl iron (CI) as filler. The SiO2 coated CI particles were prepared by Stober process. The microwave absorbing properties and the effect of heat treatment on the electromagnetic properties of SiO2 coated CI/polyimide composites were investigated. When the content of SiO2 coated CI is 60 wt%, the value of minimum reflection loss decreases from -25 dB to -33 dB with the thickness increases from 1.5 mm to 2.1 mm. According to the thermal-gravimetric analyses (TGA) curves, the polyimide matrix can be used at 300 °C for long time. The complex permittivity of the composites slightly increases while the complex permeability almost keeps constant after heat treatment at 300 °C for 10 h, which indicating that the composites can be used at elevated temperature as microwave absorbing materials at the same time have good heat resistance and microwave absorption.

  17. Improving the Adhesion Resistance of the Boride Coatings to AISI 316L Steel Substrate by Diffusion Annealing

    NASA Astrophysics Data System (ADS)

    Campos-Silva, I.; Bernabé-Molina, S.; Bravo-Bárcenas, D.; Martínez-Trinidad, J.; Rodríguez-Castro, G.; Meneses-Amador, A.

    2016-09-01

    In this study, new results about the practical adhesion resistance of boride coating/substrate system formed at the surface of AISI 316 L steel and improved by means of a diffusion annealing process are presented. First, the boriding of AISI 316 L steel was performed by the powder-pack method at 1173 K with different exposure times (4-8 h). The diffusion annealing process was conducted on the borided steels at 1273 K with 2 h of exposure using a diluent atmosphere of boron powder mixture. The mechanical behavior of the boride coating/substrate system developed by both treatments was established using Vickers and Berkovich tests along the depth of the boride coatings, respectively. Finally, for the entire set of experimental conditions, the scratch tests were performed with a continuously increasing normal force, in which the practical adhesion resistance of the boride coating/substrate system was represented by the critical load. The failure mechanisms developed over the surface of the scratch tracks were analyzed; the FeB-Fe2B/substrate system exhibited an adhesive mode, while the Fe2B/substrate system obtained by the diffusion annealing process showed predominantly a cohesive failure mode.

  18. Protein-resistant properties of a chemical vapor deposited alkyl-functional carboxysilane coating characterized using quartz crystal microbalance

    NASA Astrophysics Data System (ADS)

    Vaidya, Shyam V.; Yuan, Min; Narváez, Alfredo R.; Daghfal, David; Mattzela, James; Smith, David

    2016-02-01

    The protein-resistant properties of a chemical vapor deposited alkyl-functional carboxysilane coating (Dursan®) were compared to that of an amorphous fluoropolymer (AF1600) coating and bare 316L grade stainless steel by studying non-specific adsorption of various proteins onto these surfaces using quartz crystal microbalance with dissipation monitoring (QCM-D). A wash solution with nonionic surfactant, polyoxyethyleneglycol dodecyl ether (or Brij 35), facilitated 100% removal of the adsorbed bovine serum albumin (BSA), mouse immunoglobulin G (IgG), and normal human plasma proteins from the Dursan surface and of the adsorbed normal human plasma proteins from the AF1600 surface, whereas these proteins remained adsorbed on the bare stainless steel surface. Mechanical stress in the form of sonication demonstrated durability of the Dursan coating to mechanical wear and showed no negative impact on the coating's ability to prevent adsorption of plasma proteins. Surface delamination was observed in case of the sonicated AF1600 coating, which further led to adsorption of normal human plasma proteins.

  19. The fluoride coated AZ31B magnesium alloy improves corrosion resistance and stimulates bone formation in rabbit model.

    PubMed

    Sun, Wei; Zhang, Guangdao; Tan, Lili; Yang, Ke; Ai, Hongjun

    2016-06-01

    This study aimed to evaluate the effect of fluorine coated Mg alloy and clarify its mechanism in bone formation. We implanted the fluorine coated AZ31B Mg alloy screw (group F) in rabbit mandibular and femur in vivo. Untreated AZ31B Mg alloy screw (group A) and titanium screw (group T) were used as control. Then, scanning electron microscopy, the spectral energy distribution analysis, hard and decalcified bone tissues staining were performed. Immunohistochemistry was employed to examine the protein expressions of bone morphogenetic protein 2 (BMP-2) and collagen type I in the vicinity of the implant. Compared with the group A, the degradation of the alloy was reduced, the rates of Mg corrosion and Mg ion release were slowed down, and the depositions of calcium and phosphate increased in the group F in the early stage of implantation. Histological results showed that fluorine coated Mg alloy had well osteogenic activity and biocompatibility. Moreover, fluoride coating obviously up-regulated the expressions of collagen type I and BMP-2. This study confirmed that the fluorine coating might improve the corrosion resistance of AZ31B Mg alloy and promote bone formation by up-regulated the expressions of collagen type I and BMP-2.

  20. Improving hot corrosion resistance of two phases intermetallic alloy α2-Ti3Al/γ-TiAl with enamel coating

    NASA Astrophysics Data System (ADS)

    Pambudi, Muhammad Jajar; Basuki, Eddy Agus; Prajitno, Djoko Hadi

    2017-01-01

    TiAl intermetallic alloys have attracted great interest among aerospace industry after successful utilization in low pressure turbine blades of aircraft engine which makes dramatic weight saving up to 40% weight saving. However, poor oxidation and corrosion resistance at temperatures above 800°C still become the drawbacks of this alloys, making the development of protective coatings to improve the resistance is important. This study investigates the hot corrosion behavior of two phases intermetallic alloy α2-Ti3Al/γ-TiAl with and without enamel coating using immersion test method in molten salt of 85%-wt Na2SO4 and 15%-wt NaCl at 850°C. The results show after 50 hours of hot corrosion test, bare alloy showed poor hot corrosion resistance due to the formation of non-protective Al2O3+TiO2 mixed scale at the surface of the alloy. Improvement of hot corrosion resistance was obtained in samples protected with enamel coating, indicated by significant decreasing in mass change (mg/cm2) by 98.20%. Enamel coating is expected to has the capability in suppressing the diffusion of oxygen and corrosive ions into the substrate layer, and consequently, it improves hot corrosion resistance of the alloy. The study showed that enamel coatings have strong adherent to the substrate and no spallation was observed after hot corrosion test. Nevertheless, the dissolution of oxides components of the enamel coating into the molten salts was observed that lead enamel coating degradation. This degradation is believed involving Cl- anion penetration into the substrate through voids in the coating that accelerates the corrosion of the two phases α2-Ti3Al/γ-TiAl alloy. Even though further observations are needed, it appears that enamel coating could be a promising protective coating to increase hot corrosion resistance of TiAl intermetallic alloys.

  1. Demonstration of Corrosion-Resistant Coatings for Air-Conditioning Coils and Fins

    DTIC Science & Technology

    2015-06-01

    cost effectiveness of two of the newer coatings to protect build- ing air-conditioning condenser evaporator coils and fins from corrosion . Exposure...on-site coupons under this test be periodically revisited over the next 30 years, and the corrosion - protection performance of the two coating ...quality coating (such as the demonstrated technologies) would protect aluminum from corrosion , even in more corrosive atmospheres. Clearly, each of the

  2. Development of Oxidation Resistant Coatings on GRCop-84 Substrates by Cold Spray Process

    NASA Technical Reports Server (NTRS)

    Karthikeyan, J.

    2007-01-01

    GRCop-84, a Cu-CR-Nb alloy, has been developed for rocket engine liner applications. For maximum life additional oxidation protection is required to prevent blanching. NiCrAlY was identified as a suitable coating, and efforts were initiated to develop suitable coating techniques. Cold spray is one technique under consideration. Efforts at ASB Industries to produce dense, adherent coatings are detailed. The work culminated in the production of samples for testing at NASA Glenn Research Center.

  3. Oxidation-resistant interfacial coatings for fiber-reinforced ceramic composites

    SciTech Connect

    Lara-Curzio, Edgar; More, Karren L.; Lee, Woo Y.

    1999-04-22

    A ceramic-matrix composite having a multilayered interfacial coating adapted to protect the reinforcing fibers from long-term oxidation, while allowing these to bridge the wake of advancing cracks in the matrix, is provided by selectively mismatching materials within adjacent layers of the interfacial coating, the materials having different coefficients of thermal expansion so that a low toughness interface region is created to promote crack deflection either within an interior layer of the mismatched interfacial coating or between adjacent layers of the mismatched interfacial coating.

  4. Hyperbranched hydrocarbon surfactants give fluorocarbon-like low surface energies.

    PubMed

    Sagisaka, Masanobu; Narumi, Tsuyoshi; Niwase, Misaki; Narita, Shioki; Ohata, Atsushi; James, Craig; Yoshizawa, Atsushi; Taffin de Givenchy, Elisabeth; Guittard, Frédéric; Alexander, Shirin; Eastoe, Julian

    2014-06-03

    Two series of Aerosol-OT-analogue surfactants (sulfosuccinate-type di-BCnSS and sulfoglutarate-type di-BCnSG) with hyperbranched alkyl double tails (so-called "hedgehog" groups, carbon number n = 6, 9, 12, and 18) have been synthesized and shown to demonstrate interfacial properties comparable to those seen for related fluorocarbon (FC) systems. Critical micelle concentration (CMC), surface tension at the CMC (γCMC), and minimum area per molecule (Amin) were obtained from surface tension measurements of aqueous surfactant solutions. The results were examined for relationships between the structure of the hedgehog group and packing density at the interface. To evaluate A and B values in the Klevens equation for these hedgehog surfactants, log(CMC) was plotted as a function of the total carbon number in the surfactant double tail. A linear relationship was observed, producing B values of 0.20-0.25 for di-BCnSS and di-BCnSG, compared to a value of 0.31 for standard double-straight-tail sulfosuccinate surfactants. The lower B values of these hedgehog surfactants highlight their lower hydrophobicity compared to double-straight-tail surfactants. To clarify how hydrocarbon density in the surfactant-tail layer (ρ(layer)) affects γCMC, the ρ(layer) of each double-tail surfactant was calculated and the relationship between γCMC and ρ(layer) examined. As expected for the design of low surface energy surfactant layers, ρ(layer) was identified as an important property for controlling γCMC with higher ρ(layer), leading to a lower γCMC. Interestingly, surfactants with BC9 and BC12 tails achieved much lower γCMC, even at low ρ(layer) values of <0.55 g cm(-3). The lowest surface energy surfactant studied here was di-BC6SS, which had a γCMC of only 23.8 mN m(-1). Such a low γCMC is comparable to those obtained with short FC-tail surfactants (e.g., 22.0 mN m(-1) for the sulfosuccinate-type FC-surfactant with R = F(CF2)6CH2CH2-).

  5. 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.

  6. Synthesis of organic-inorganic hybrid sols with nano silica particles and organoalkoxysilanes for transparent and high-thermal-resistance coating films using sol-gel reaction.

    PubMed

    Na, Moonkyong; Park, Hoyyul; Ahn, Myeongsang; Lee, Hyeonhwa; Chung, Ildoo

    2010-10-01

    Organic-inorganic hybrid sols were synthesized from nano silica particles dispersed in water and from organoalkoxysilanes, using the sol-gel reaction. This work focuses on the effects of the three multifunctional organoalkoxysilanes dimethyldimethoxysilane (DMDMS), methyltrimethoxysilane (MTMS), and tetramethoxysilane (TMOS) to form a transparent and high-thermal-resistance coating film. The stability of the hybrid sol was evaluated as a function of the reaction time for 10 d through the variation of the viscosity. The viscosity of the silica/DMDMS and silica/MTMS sol was slightly increased for 10 d. The multifunctional organoalkoxysilanes formed dense silica networks through hydrolysis and condensation reaction, which enhanced the thermal resistance of the coating films. No thermal degradation of the silica/DMDMS sample occurred up to 600 degrees C, and none of the silica/MTMS and silica/TMOS samples occurred either up to 700 degrees C. The organic-inorganic hybrid sols were coated on the glass substrate using a spin-coating procedure. The organic-inorganic hybrid sols formed flat coating films without cracks. The transmittance of the hybrid sol coating films using MTMS and DMDMS was shown to be over 90%. The transmittance of the silica/TMOS sol coating film reacted for 10 d abruptly decreased due to faster gelation. The silica/DMDMS and silica/MTMS hybrid sols formed smooth coating films while the surface roughness of the silica/TMOS coating film markedly increased when the hybrid sol reacted for 10 d. The increase of the surface roughness of the silica/TMOS coating film can be attributed to the degradation of the stability of the hybrid sol and to the loss of transmittance of the coating film. It was confirmed in this study that the use of organic-inorganic hybrid sol can yield transparent and high-thermal-resistance coating films.

  7. Reduced platelet adhesion and improved corrosion resistance of superhydrophobic TiO₂-nanotube-coated 316L stainless steel.

    PubMed

    Huang, Qiaoling; Yang, Yun; Hu, Ronggang; Lin, Changjian; Sun, Lan; Vogler, Erwin A

    2015-01-01

    Superhydrophilic and superhydrophobic TiO2 nanotube (TNT) arrays were fabricated on 316L stainless steel (SS) to improve corrosion resistance and hemocompatibility of SS. Vertically-aligned superhydrophilic amorphous TNTs were fabricated on SS by electrochemical anodization of Ti films deposited on SS. Calcination was carried out to induce anatase phase (superhydrophilic), and fluorosilanization was used to convert superhydrophilicity to superhydrophobicity. The morphology, structure and surface wettability of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and contact angle goniometry. The effects of surface wettability on corrosion resistance and platelet adhesion were investigated. The results showed that crystalline phase (anatase vs. amorphous) and wettability strongly affected corrosion resistance and platelet adhesion. The superhydrophilic amorphous TNTs failed to protect SS from corrosion whereas superhydrophobic amorphous TNTs slightly improved corrosion resistance of SS. Both superhydrophilic and superhydrophobic anatase TNTs significantly improved corrosion resistance of SS. The superhydrophilic amorphous TNTs minimized platelet adhesion and activation whereas superhydrophilic anatase TNTs activated the formation of fibrin network. On the contrary, both superhydrophobic TNTs (superhydrophobic amorphous TNTs and superhydrophobic anatase TNTs) reduced platelet adhesion significantly and improved corrosion resistance regardless of crystalline phase. Superhydrophobic anatase TNTs coating on SS surface offers the opportunity for the application of SS as a promising permanent biomaterial in blood contacting biomedical devices, where both reducing platelets adhesion/activation and improving corrosion resistance can be effectively combined.

  8. Plasma-deposited fluorocarbon polymer films on titanium for preventing cell adhesion: a surface finishing for temporarily used orthopaedic implants

    NASA Astrophysics Data System (ADS)

    Finke, B.; Testrich, H.; Rebl, H.; Walschus, U.; Schlosser, M.; Zietz, C.; Staehlke, S.; Nebe, J. B.; Weltmann, K. D.; Meichsner, J.; Polak, M.

    2016-06-01

    The design of a titanium implant surface should ideally support its later application in clinical use. Temporarily used implants have to fulfil requirements different from permanent implants: they should ensure the mechanical stabilization of the bone stock but in trauma surgery they should not be integrated into the bone because they will be removed after fracture healing. Finishing of the implant surface by a plasma-fluorocarbon-polymer (PFP) coating is a possible approach for preventing cell adhesion of osteoblasts. Two different low pressure gas-discharge plasma processes, microwave (MW 2.45 GHz) and capacitively coupled radio frequency (RF 13.56 MHz) plasma, were applied for the deposition of the PFP film using a mixture of the precursor octafluoropropane (C3F8) and hydrogen (H2). The thin films were characterized by x-ray photoelectron spectroscopy, Fourier transform infrared reflection absorption spectroscopy, and water contact angle measurements. Cell culture experiments show that cell adhesion and spreading of MG-63 osteoblasts were clearly reduced or nonexistent on these surfaces, also after 24 h of storage in the cell culture medium. In vivo data demonstrated that the local inflammatory tissue response for the PFP films deposited in MW and RF plasma were comparable to uncoated controls.

  9. Impact Resistance of Environmental Barrier Coated SiC/SiC Composites

    NASA Technical Reports Server (NTRS)

    Bhatt, Ramakrishna T.; Choi, Sung R.; Cosgriff, Laura M.; Fox, Dennis S.; Lee, Kang N.

    2008-01-01

    Impact performance of 2D woven SiC/SiC composites coated with 225 and 525 microns thick environmental barrier coating (EBC) was investigated. The composites were fabricated by melt infiltration and the EBC was deposited by plasma spray. Impact tests were conducted at room temperature and at 1316 C in air using 1.59 mm diameter steel-balls at projectile velocities ranging from 110 to 375 m/s . Both microscopy and non-destructive evaluation (NDE) methods were used to determine the extent of damage in the substrate and coating with increasing projectile velocity. The impacted specimens were tensile tested at room temperature to determine their residual mechanical properties. At projectile velocities less than 125 m/s , no detectable internal damage was noticed in the MI SiC/SiC composites coated with 525 microns EBC. With increase in projectile velocity beyond this value, spallation of EBC layers, delamination of fiber plies, and fiber fracture were detected. At a fixed projectile velocity, the composites coated with 525 microns EBC showed less damage than those coated with 225 microns EBC. Both types of coated composites retained a large fraction of the baseline properties of the as-fabricated composites and exhibited non-brittle failure after impact testing. Furnace exposure of impacted specimens in a moisture environment at 1316 C for 500 h indicated that the through-the-thickness cracks in the coating and delamination cracks in the substrate generated after impact testing acted as conduits for internal oxidation.

  10. Deposition of Wear and Corrosion Resistant Coatings onto Landing Gear Components Via Directed Vapor Deposition

    DTIC Science & Technology

    2007-01-01

    Multilayer coatings • Combinatorial synthesis • Reactive deposition of oxides and nitrides • Supersonic gas jet focuses vapor flux onto substrate...velocity oxy -fuel (HVOF) process cannot be used. 3) Demonstrate that the coating is viable for sealing surfaces, where a surface finish of 8 to 12 micro

  11. Improved biocompatibility of thrombo-resistant iron-polysaccharides multilayer coatings on nitinols.

    PubMed

    Ma, Yan; Liu, Meng; Yue, Xiuli; Zha, Zhengbao; Dai, Zhifei

    2010-01-01

    Biocompatibility of two multilayer coatings of (Fe3+/Hep)10 and (Fe3+/DS/Fe3+/Hep)5 was comparatively analyzed with respect to protein adsorption, leukocyte adhesion and cell-material interaction. Both of them showed significantly high albumin-to-fibrinogen adsorption ratio, suggesting good biocompatibility. Furthermore, the (Fe3+/DS/Fe3+/Hep)5 coating was found to exhibit the lowest non-specific protein adsorption due to the incorporation of dextran sulfate. Compared with uncoated Nitinol surfaces, iron-polysaccharide multilayer coating presented no deformation of leukocytes, indicating no signs of inflammatory reactions. Cell growth, cell adhesion and cell metabolic activity were all in good condition, verifying both (Fe3+/Hep)10 and (Fe3+/DS/Fe3+/Hep)5 coatings had good cytocompatibility. Therefore, iron-polysaccharides multilayer coatings had greatly improved the biocompatibility of Nitinols.

  12. Oxidation-resistant interface coatings for SiC/SiC composites

    SciTech Connect

    Stinton, D.P.; Kupp, E.R.; Hurley, J.W.; Lowden, R.A.

    1996-08-01

    The characteristics of the fiber-matrix interfaces in ceramic matrix composites control the mechanical behavior of these composites. Finite element modeling (FEM) was performed to examine the effect of interface coating modulus and coefficient of thermal expansion on composite behavior. Oxide interface coatings (mullite and alumina-titania) produced by a sol-gel method were chosen for study as a result of the FEM results. Amorphous silicon carbide deposited by chemical vapor deposition (CVD) is also being investigated for interface coatings in SiC-matrix composites. Processing routes for depositing coatings of these materials were developed. Composites with these interfaces were produced and tested in flexure both as-processed and after oxidation to examine the suitability of these materials as interface coatings for SiC/SiC composites in fossil energy applications.

  13. Very Tough, Erosion-Resistant Turbine Airfoil Thermal Barrier Coatings Developed

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming; Miller, Robert A.

    2005-01-01

    Ceramic thermal barrier coatings (TBCs) are receiving increased attention for advanced gas turbine engine applications. These coatings are considered to be technologically important because of their ability to further increase engine operating temperatures and reduce cooling requirements, thus achieving higher engine efficiency, lower emissions, and increased performance goals. To take full advantage of the capabilities of these coatings, researchers need to use an aggressive design approach whenever possible--one that allows greater temperature reductions through the coating systems and less cooling air to the components. Advanced TBCs that have significantly lower thermal conductivity and better thermal stability than current coatings have been developed for future ultra-efficient, low-emission engine systems. Multicomponent-doped, defect-clustered TBCs have been shown to offer the low conductivity and high stability required for future high-temperature engine applications.

  14. Oxidation-resistant interface coatings for SiC/SiC composites

    SciTech Connect

    Stinton, D.P.; Kupp, E.R.; Hurley, J.W.

    1996-06-01

    The characteristics of the fiber-matrix interfaces in ceramic matrix composites control the mechanical behavior of these composites. Finite element modeling (FEM) was performed to examine the effect of interface coating modulus and coefficient of thermal expansion on composite behavior. Oxide interface coatings (mullite and alumina-titania) produced by a sol-gel method were chosen for study as a result of the FEM results. Amorphous silicon carbide deposited by chemical vapor deposition (CVD) is also being investigated for interface coatings in SiC-matrix composites. Processing routes for depositing coatings of these materials were developed. Composites with these interfaces were produced and tested in flexure both as-processed and after oxidation to examine the suitability of these materials as interface coatings for SiC/SiC composites in fossil energy applications.

  15. Thermal control/oxidation resistant coatings for titanium-based alloys

    NASA Technical Reports Server (NTRS)

    Clark, Ronald K.; Wallace, Terryl A.; Cunnington, George R.; Wiedemann, Karl E.

    1992-01-01

    Extensive research and development efforts have been expended toward development of thermal control and environmental protection coatings for NASP and generic hypersonic vehicle applications. The objective of the coatings development activities summarized here was to develop light-weight coatings for protecting advanced titanium alloys from oxidation in hypersonic vehicle applications. A number of new coating concepts have been evaluated. Coated samples were exposed to static oxidation tests at temperatures up to 1000 C using a thermogravimetric apparatus. Samples were also exposed to simulated hypersonic flight conditions for up to 10 hr to determine their thermal and chemical stability and catalytic efficiency. The emittance of samples was determined before and after exposure to simulated hypersonic flight conditions.

  16. Protective Coatings to Promote Oxidation Resistance, Wear Resistance, and Damage Tolerance to Composite Structures using the LTAVD Process.

    DTIC Science & Technology

    1995-01-01

    in Phase I were Zirconium Nitride [ZrN], Titanium Nitride [TiN], Copper-Chromium [CuCr], amorphous diamond, and Titanium Diboride [TiB2 ] on three...process conditions that were compatible with composite substrates. A thin film (1.0 Atm thick) of Zirconium Nitride [ZrN] was deposited on the Gr/E...the internal components for the LTAVD coating process. 9 3. Zirconium Nitride (ZrN) coating (3.0 um-thick) on composite laminates. 11 4. Titanium

  17. Effect of Spray Particle Velocity on Cavitation Erosion Resistance Characteristics of HVOF and HVAF Processed 86WC-10Co4Cr Hydro Turbine Coatings

    NASA Astrophysics Data System (ADS)

    Kumar, R. K.; Kamaraj, M.; Seetharamu, S.; Pramod, T.; Sampathkumaran, P.

    2016-08-01

    The hydro plants utilizing silt-laden water for power generation suffer from severe metal wastage due to particle-induced erosion and cavitation. High-velocity oxy-fuel process (HVOF)-based coatings is widely applied to improve the erosion life. The process parameters such as particle velocity, size, powder feed rate, temperature, affect their mechanical properties. The high-velocity air fuel (HVAF) technology, with higher particle velocities and lower spray temperatures, gives dense and substantially nonoxidized coating. In the present study, the cavitation resistance of 86WC-10Co4Cr-type HVOF coating processed at 680 m/s spray particle velocity was compared with HVAF coatings made at 895, 960, and 1010 m/s. The properties such as porosity, hardness, indentation toughness, and cavitation resistance were investigated. The surface damage morphology has been analyzed in SEM. The cohesion between different layers has been examined qualitatively through scratch depth measurements across the cross section. The HVAF coatings have shown a lower porosity, higher hardness, and superior cavitation resistance. Delamination, extensive cracking of the matrix interface, and detachment of the WC grains were observed in HVOF coating. The rate of metal loss is low in HVAF coatings implying that process parameters play a vital role in achieving improved cavitation resistance.

  18. Microstructure and Wear Resistance of Composite Coating by Laser Cladding Al/TiN on the Ti-6Al-4V Substrate

    NASA Astrophysics Data System (ADS)

    Zhang, H. X.; Yu, H. J.; Chen, C. Z.

    2015-05-01

    The composite coatings were fabricated by laser cladding Al/TiN pre-placed powders on Ti-6Al-4V substrate for enhancing wear resistance and hardness of the substrate. The composite coatings were analyzed by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The sliding wear tests were performed by MM200 wear test machine. The hardness of the coatings was tested by HV-1000 hardness tester. After laser cladding, it was found that there was a good metallurgical bond between the coating and the substrate. The composite coatings were mainly composed of the matrix of β-Ti (Al) and the reinforcements of titanium nitride (TiN), Ti3Al, TiAl and Al3Ti. The hardness and wear resistance of the coatings on four samples were greatly improved, among which sample 4 exhibited the highest hardness and best wear resistance. The hardness of the coating on sample 4 was approximately 2.5 times of the Ti-6Al-4V substrate. And the wear resistance of sample 4 was four times of the substrate.

  19. Influence of Applied Voltage and Film-Formation Time on Microstructure and Corrosion Resistance of Coatings Formed on Mg-Zn-Zr-Ca Bio-magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Yandong, Yu; Shuzhen, Kuang; Jie, Li

    2015-09-01

    The influence of applied voltage and film-formation time on the microstructure and corrosion resistance of coatings formed on a Mg-Zn-Zr-Ca novel bio-magnesium alloy has been investigated by micro-arc oxidation (MAO) treatment. Phase composition and microstructure of as-coated samples were analyzed by the x-ray diffraction, energy dispersive x-ray spectroscopy and scanning electron microscopy. And the porosity and average of micro-pore aperture of the surface on ceramic coatings were analyzed by general image software. Corrosion microstructure of as-coated samples was caught by a microscope digital camera. The long-term corrosion resistance of as-coated samples was tested in simulated body fluid for 30 days. The results showed that the milky white smooth ceramic coating formed on the Mg-Zn-Zr-Ca novel bio-magnesium alloy was a compound of MgO, Mg2SiO4 and MgSiO3, and its corrosion resistance was significantly improved compared with that of the magnesium substrate. In addition, when the MAO applied voltage were 450 V and 500 V and film-formation time were 9 min and 11 min, the surface micro-morphology and the corrosion resistance of as-coated samples were relatively improved. The results provided a theoretical foundation for the application of the Mg-Zn-Zr-Ca novel bio-magnesium alloy in biomedicine.

  20. Corrosion resistance of flaky aluminum pigment coated with cerium oxides/hydroxides in chloride and acidic electrolytes

    NASA Astrophysics Data System (ADS)

    Niroumandrad, S.; Rostami, M.; Ramezanzadeh, B.

    2015-12-01

    The objective of this study was to enhance the corrosion resistance of lamellar aluminum pigment through surface treatment by cerium oxides/hydroxides. The surface composition of the pigments was studied by energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the pigment was evaluated by conventional hydrogen evolution measurements in acidic solution and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. Results showed that the Ce-rich coating composed of Ce2O3 and CeO2 was precipitated on the pigment surface after immersion in the cerium solution. The corrosion resistance of pigment was significantly enhanced after modification with cerium layer.

  1. Fabrication of Oxidation-Resistant Metal Wire Network-Based Transparent Electrodes by a Spray-Roll Coating Process.

    PubMed

    Kiruthika, S; Gupta, Ritu; Anand, Aman; Kumar, Ankush; Kulkarni, G U

    2015-12-16

    Roll and spray coating methods have been employed for the fabrication of highly oxidation resistant transparent and conducting electrodes (TCEs) by a simple solution process using crackle lithography technique. We have spray-coated a crackle paint-based precursor to produce highly interconnected crackle network on PET roll mounted on a roll coater with web speed of 0.6 m/min. Ag TCE with a transmittance of 78% and sheet resistance of ∼20 Ω/□ was derived by spraying Ag precursor ink over the crackle template followed by lift-off and annealing under ambient conditions. The Ag wire mesh was stable toward bending and sonication tests but prone to oxidation in air. When electrolessly coated with Pd, its robustness toward harsh oxidation conditions was enhanced. A low-cost transparent electrode has also been realized by using only small amounts of Ag as seed layer and growing Cu wire mesh by electroless method. Thus, made Ag/Cu meshes are found to be highly stable for more than a year even under ambient atmosphere.

  2. Process for the deposition of high temperature stress and oxidation resistant coatings on silicon-based substrates

    DOEpatents

    Sarin, V.K.

    1991-07-30

    A process is disclosed for depositing a high temperature stress and oxidation resistant coating on a silicon nitride- or silicon carbide-based substrate body. A gas mixture is passed over the substrate at about 900--1500 C and about 1 torr to about ambient pressure. The gas mixture includes one or more halide vapors with other suitable reactant gases. The partial pressure ratios, flow rates, and process times are sufficient to deposit a continuous, fully dense, adherent coating. The halide and other reactant gases are gradually varied during deposition so that the coating is a graded coating of at least two layers. Each layer is a graded layer changing in composition from the material over which it is deposited to the material of the layer and further to the material, if any, deposited thereon, so that no clearly defined compositional interfaces exist. The gases and their partial pressures are varied according to a predetermined time schedule and the halide and other reactant gases are selected so that the layers include (a) an adherent, continuous intermediate layer about 0.5-20 microns thick of an aluminum nitride or an aluminum oxynitride material, over and chemically bonded to the substrate body, and (b) an adherent, continuous first outer layer about 0.5-900 microns thick including an oxide of aluminum or zirconium over and chemically bonded to the intermediate layer.

  3. Process for the deposition of high temperature stress and oxidation resistant coatings on silicon-based substrates

    DOEpatents

    Sarin, Vinod K.

    1991-01-01

    A process for depositing a high temperature stress and oxidation resistant coating on a silicon nitride- or silicon carbide-based substrate body. A gas mixture is passed over the substrate at about 900.degree.-1500.degree. C. and about 1 torr to about ambient pressure. The gas mixture includes one or more halide vapors with other suitable reactant gases. The partial pressure ratios, flow rates, and process times are sufficient to deposit a continuous, fully dense, adherent coating. The halide and other reactant gases are gradually varied during deposition so that the coating is a graded coating of at least two layers. Each layer is a graded layer changing in composition from the material over which it is deposited to the material of the layer and further to the material, if any, deposited thereon, so that no clearly defined compositional interfaces exist. The gases and their partial pressures are varied according to a predetermined time schedule and the halide and other reactant gases are selected so that the layers include (a) an adherent, continuous intermediate layer about 0.5-20 microns thick of an aluminum nitride or an aluminum oxynitride material, over and chemically bonded to the substrate body, and (b) an adherent, continuous first outer layer about 0.5-900 microns thick including an oxide of aluminum or zirconium over and chemically bonded to the intermediate layer.

  4. Understanding deviations in lithographic patterns near interfaces: Characterization of bottom anti-reflective coatings (BARC) and the BARC resist interface

    NASA Astrophysics Data System (ADS)

    Lenhart, Joseph L.; Fischer, Daniel; Sambasivan, Sharadha; Lin, Eric K.; Wu, Wen-Li; Guerrero, Douglas J.; Wang, Yubao; Puligadda, Rama

    2007-02-01

    Interactions between a bottom anti-reflective coating (BARC) and a photoresist can critically impact lithographic patterns. For example, a lithographic pattern can shrink or spread near a BARC interface, a process called undercutting or footing respectively, due to incompatibility between the two materials. Experiments were conducted on two industrial BARC coatings in an effort to determine the impact of BARC surface chemistry on the footing and undercutting phenomena. The BARC coatings were characterized by near edge X-ray absorption fine structure (NEXAFS), contact angle measurements, and neutron and X-ray reflectivity. Contact angle measurement using a variety of fluids showed that the fluid contact angles were independent of the type of BARC coating or the BARC processing temperature. NEXAFS measurements showed that the surface chemistry of each BARC was also independent of the processing temperature. These results suggest that acid-base interactions at the BARC-resist interface are not the cause of the footing-undercutting phenomena encountered in lithographic patterns.

  5. Mechanical Properties and Thermal Shock Resistance of HVOF Sprayed NiCrAlY Coatings Without and With Nano Ceria

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoguang; Chen, Shufen; Wang, You; Pan, Zhaoyi; Wang, Liang

    2012-09-01

    NiCrAlY coatings without and with 0.2 wt.% nano ceria were prepared by high velocity oxygen fuel spraying. The microstructure, mechanical properties, and thermal shock resistance of as-sprayed coatings were investigated. The results showed that in the as-sprayed coatings, the number of un-melted particles was reduced drastically, the microstructure was refined and compact due to the refinement of sprayable powders. Both the hardness and adhesive strength of the NiCrAlY increased due to the refinement of microstructure and the decrease of the defects, such as pores and oxides, after adding nano ceria. The thermal cycle life of NiCrAlY coatings was improved by 15% after adding 0.2 wt.% nano ceria, which is attributed to the low content of spinel NiCr2O4 and high content of Cr2O3 in the thermal cycling, the refined and compact microstructure, and increased interfacial boundary.

  6. Development of Hydrophobic Coatings for Water-Repellent Surfaces Using Hybrid Methodology

    DTIC Science & Technology

    2014-04-01

    water-repellent, and antimicrobial properties . Several approaches have been investigated for the development of hydrophobic and superhydrophobic... liquid precursors with different fluorocarbon structures and deposition time varied as well as the SiO2 nanoparticle loading. These parameters varied to...4 1 1. Introduction Coatings that impart hydrophobic properties are of considerable interest. For applications such as aircraft

  7. Innovation of Ultrafine Structured Alloy Coatings Having Superior Mechanical Properties and High Temperature Corrosion Resistance

    NASA Astrophysics Data System (ADS)

    Ma, X. Q.; Gandy, D. W.; Frederick, G. J.

    2008-12-01

    High temperature protection requires full coating density, high adhesion, minor oxide inclusions, and preferably fine grains, which is not achievable in most thermal spray processes. High velocity oxygen fuel (HVOF) thermal spray process has been applied extensively for making such coatings with the highest density and adhesion strength, but the existence of not melted or partially melted particles are usually observed in the HVOF coatings because of relatively low flame temperature and short particle resident time in the process. This work has investigated the development of an innovative HVOF process using a liquid state suspension/slurry containing small alloy powders. The advantages of using small particles in a HVOF process include uniform coating, less defective microstructure, higher cohesion and adhesion, full density, lower internal stress, and higher deposition efficiency. Process investigations have proven the benefits of making alloy coatings with full density and high bond strength attributing to increased melting of the small particles and the very high kinetic energy of particles striking on the substrate. High temperature oxidation and hot corrosion tests at 800 °C have demonstrated that the alloy coatings made by novel LS-HVOF process have superior properties to conventional counterpart coatings in terms of oxidation rates and corrosion penetration depths.

  8. Foreign Object Damage Resistance of Uncoated and EBC Coated SiC/SiC Composites

    NASA Technical Reports Server (NTRS)

    Bhatt, R. T.; Choi, S. R.; Cosgriff, L. M.; Fox, D.; Lee, K. N.

    2004-01-01

    SiC/SiC composites fabricated by the melt infiltration method are candidate materials for the turbine components such as combustor liners, nozzle vanes and blades because of their high temperature strength, and thermal conductivity. To avoid surface recession in a combustion environment containing moisture, these materials also require an environmental barrier coating (EBC). Under thermal loading condition alone, the EBC coated SiC/SiC components show microstructural and strength stability after -1 5000 hr exposure to 12OO0C in combustion environment. However, the stability of SiC/SiC composites under impact conditions is not fully understood. In this study, both uncoated and EBC coated SiC/SiC composite specimens were impact tested by steel-ball projectiles at room temperature and at 1300 C in air. After impact, the specimens were analyzed under a scanning electron microscope to assess coating damage, and then tensile and bend tested at room temperature to determine their residual strength. The extent of coating and substrate damage with increasing projectile velocity was imaged and analyzed using nondestructive evaluation (NDE) methods such as micro focus x-ray radiography, tomography, and thermal wave imaging. The mechanical property results of impacted specimens are correlated with the NDE results and the scanning electron microscopy (SEM) observations. Influence of projectile velocity on impact damage of the coating/substrate, and the implication coating damage on durability of the composite will be discussed.

  9. Rolling-contact fatigue resistance of hard coatings on bearing steels.

    SciTech Connect

    Erdemir, A.

    1999-08-18

    Ball- and roller-bearings of the 21st Century are expected to perform better and last longer while operating under more stringent conditions than before. To meet these great expectations, researchers have been constantly exploring new bearing designs or refining existing ones, optimizing microstructure and chemistry of bearing materials, and alternatively, they have been considering the use of thin hard coatings for improved bearing performance and durability. Already, some laboratory tests have demonstrated that hard nitride, carbide (such as TiN, TiC, etc.) and diamondlike carbon (DLC) coatings can be very effective in prolonging the fatigue lives of bearing steels. This paper provides an overview of the recent developments in hard coatings for bearing applications. Previous studies have demonstrated that thin, hard coatings can effectively prolong the fatigue lives of bearing steel substrates. In particular, thinner hard coatings (i.e., 0.2 - 1 {micro}m thick) provide exceptional improvements in the fatigue lives of bearing steel substrates. In contrast, thicker hard coatings suffer micro fracture and delamination when tested under high contact stresses, hence are ineffective and may even have a negative effect on bearing life. Overall, it was concluded that thin hard coatings may offer new possibilities for bearing industry in meeting the performance and durability needs of the 21st Century.

  10. Interdiffusion Behavior of Al-Rich Oxidation Resistant Coatings on Ferritic-Martensitic Alloys

    SciTech Connect

    Velraj, S.; Zhang, Ying; Hawkins, W. E.; Pint, Bruce A.

    2012-06-21

    We investigated interdiffusion of thin Al-rich coatings synthesized by chemical vapor deposition (CVD) and pack cementation on 9Cr ferritic–martensitic alloys in the temperature range of 650–700°C. The compositional changes after long-term exposures in laboratory air and air + 10 vol% H2O were examined experimentally. Interdiffusion was modeled by a modified coating oxidation and substrate interdiffusion model (COSIM) program. The modification enabled the program to directly input the concentration profiles of the as-deposited coating determined by electron probe microanalysis (EPMA). Reasonable agreement was achieved between the simulated and experimental Al profiles after exposures. Moreover, the model was also applied to predict coating lifetime at 650–700°C based on a minimum Al content (Cb) required at the coating surface to re-form protective oxide scale. In addition to a Cb value established from the failure of a thin CVD coating at 700°C, values reported for slurry aluminide coatings were also included in lifetime predictions.

  11. A new strategy for improvement of the corrosion resistance of a green cerium conversion coating through thermal treatment procedure before and after application of epoxy coating

    NASA Astrophysics Data System (ADS)

    Mahidashti, Z.; Shahrabi, T.; Ramezanzadeh, B.

    2016-12-01

    The effect of post-heating of CeCC on its surface morphology and chemistry has been studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and contact angle (CA) measurements. The corrosion protection performance of the coatings was investigated by electrochemical impedance spectroscopy (EIS). The effect of thermal treatment of CeCC on the corrosion protection performance of epoxy coating was investigated by EIS. Results showed that the heat treatment of Ce film noticeably improved its corrosion resistance and adhesion properties compared to that of untreated samples. The CeCC deposited on the steel substrate at room temperature had a highly cracked structure, while the amount of micro-cracks significantly reduced after post-heating procedure. Results obtained from EIS analysis confirmed the effect of post-heating of CeCC on its corrosion protection performance enhancement. The increase of post-heating temperature and time up to 140 °C and 3 h led to better results.

  12. Effect of the quality of powder materials on the properties of the wear-resistant coatings on the rotor blades in an aviation gas-turbine engine compressor

    NASA Astrophysics Data System (ADS)

    Abraimov, N. V.; Ryabenko, B. V.; Kryukov, M. A.

    2015-06-01

    The physicomechanical properties, the structures of a wear-resistant WC-Co coating on a VT3-1 titanium alloy and the powder materials used for their deposition by gas-detonation method are studied. The VK-25M coatings are found to inherit the chemical and phase compositions of the powders. The properties of the coating are substantially dependent on the shape, the sizes, and the ratio of carbide WC granules in commercial powder materials. A high content of coarse lamellar WC fractions is accompanied by an increase in the hardness and a decrease in the ductility and the fracture toughness of the coatings. The tensile stresses in the VK-25M coating on the VT3-1 titanium alloy and the fracture toughness decrease as the coating thickness increases or annealing is applied.

  13. Development of Abrasion-Resistant Coating for Solar Reflective Films. Cooperative Research and Development Final Report, CRADA Number CRD-07-247

    SciTech Connect

    Gray, Matthew

    2015-10-01

    The purpose of this CRADA is to develop an abrasion-resistant coating, suitable for use on polymeric-based reflective films (e.g., the ReflecTech reflective film), that allows for improved scratch resistance and enables the use of aggressive cleaning techniques (e.g., direct contact methods like brushing) without damaging the specular reflectance properties of the reflective film.

  14. Benzoylsalicylic acid isolated from seed coats of Givotia rottleriformis induces systemic acquired resistance in tobacco and Arabidopsis.

    PubMed

    Kamatham, Samuel; Neela, Kishore Babu; Pasupulati, Anil Kumar; Pallu, Reddanna; Singh, Surya Satyanarayana; Gudipalli, Padmaja

    2016-06-01

    Systemic acquired resistance (SAR), a whole plant defense response to a broad spectrum of pathogens, is characterized by a coordinated expression of a large number of defense genes. Plants synthesize a variety of secondary metabolites to protect themselves from the invading microbial pathogens. Several studies have shown that salicylic acid (SA) is a key endogenous component of local and systemic disease resistance in plants. Although SA is a critical signal for SAR, accumulation of endogenous SA levels alone is insufficient to establish SAR. Here, we have identified a new acyl derivative of SA, the benzoylsalicylic acid (BzSA) also known as 2-(benzoyloxy) benzoic acid from the seed coats of Givotia rottleriformis and investigated its role in inducing SAR in tobacco and Arabidopsis. Interestingly, exogenous BzSA treatment induced the expression of NPR1 (Non-expressor of pathogenesis-related gene-1) and pathogenesis related (PR) genes. BzSA enhanced the expression of hypersensitivity related (HSR), mitogen activated protein kinase (MAPK) and WRKY genes in tobacco. Moreover, Arabidopsis NahG plants that were treated with BzSA showed enhanced resistance to tobacco mosaic virus (TMV) as evidenced by reduced leaf necrosis and TMV-coat protein levels in systemic leaves. We, therefore, conclude that BzSA, hitherto unknown natural plant product, is a new SAR inducer in plants.

  15. Manufacturing Techniques for Application of Erosion Resistant Coatings to Turbine Engine Compressor Components.

    DTIC Science & Technology

    these systems for 403 stainless steel and AM355 production hardware was undertaken. The program was divided into three phases: Coating optimization; Process scale-up; and Engine qualification and environmental tests. (Author)

  16. Facile preparation of superamphiphobic epoxy resin/modified poly(vinylidene fluoride)/fluorinated ethylene propylene composite coating with corrosion/wear-resistance

    NASA Astrophysics Data System (ADS)

    Wang, Huaiyuan; Liu, Zhanjian; Wang, Enqun; Zhang, Xiguang; Yuan, Ruixia; Wu, Shiqi; Zhu, Yanji

    2015-12-01

    A robust superamphiphobic epoxy resin (EP)/modified poly(vinylidene fluoride) (MPVDF)/fluorinated ethylene propylene (FEP) composite coating has been prepared through the combination of chemical modification and spraying technique. Nanometer silica (SiO2, 2.5 wt.%) and carbon nanotubes (CNTs, 2.5 wt.%) were added in the coating to construct the necessary reticulate papillae structures for superamphiphobic surface. The prepared EP composite coating demonstrated high static contact angles (166°, 155°) and low sliding angles (3°, 5°) to water and glycerol, respectively. Moreover, the prepared coating can also retain superhydrophobicity under strongly acidic and alkaline conditions. The brittleness of EP can be avoided by introducing the malleable MPVDF. The wear life of the EP composite coating with 25 wt.% FEP was improved to 18 times of the pure EP coating. The increased wear life of the coating can be attributed to the designed nano/micro structures, the self-lubrication of FEP and the chemical reaction between EP and MPVDF. The anti-corrosion performance of the coatings was investigated in 3.5% NaCl solution using potentiodynamic polarization. The results showed that the prepared superamphiphobic composite coating was most effective in corrosion resistance, primarily due to the barrier effect for the diffusion of O2 and H2O molecules. It is believed that this robust superamphiphobic EP/MPVDF/FEP composite coating prepared by the facile spray method can pave a way for the large-scale application in pipeline transport.

  17. Impact Resistance of EBC Coated SiC/SiC Composites

    NASA Technical Reports Server (NTRS)

    Fox, Dennis S.; Bhatt, Ramakrishna T.; Choi, Sung R.; Cosgriff, Laura M.; Fox, Dennis s.; Lee, Kang N.

    2008-01-01

    Impact performance of 2-D woven SiC/SiC composites coated with 225 and 525 m thick environmental barrier coating (EBC) was investigated. The composites were fabricated by melt infiltration and the EBC was deposited by plasma spray. Impact tests were conducted at room temperature and at 1316 C in air using 1.59-mm diameter steel-balls at projectile velocities ranging from 110 to 375 m/s. Both microscopy and nondestructive evaluation (NDE) methods were used to determine the extent of damage in the substrate and coating with increasing projectile velocity. The impacted specimens were tensile tested at room temperature to determine their residual mechanical properties. At projectile velocities less than 125 m/s, no detectable damage was noticed in the MI SiC/SiC composites coated with 525 m EBC. With increase in projectile velocity beyond this value, spallation of EBC layers, delamination of fiber plies, and fiber fracture were detected. At a fixed projectile velocity, the composites coated with 525 m EBC showed less damage than the composite coated with 225 m EBC. Both types of EBC coated composites retained a large fraction of the baseline properties of as-fabricated composites and exhibited non-brittle failure after impact testing at projectile velocities up to 375 m/s. Exposure of impact tested specimens in a moisture environment at 1316 C for 500 hr indicated that the through-the-thickness cracks in the EBC coating and delamination cracks in the substrate generated after impact testing acted as conduits for internal oxidation.

  18. Coating processes for increasing the moisture resistance of polyurethane baffle material

    NASA Technical Reports Server (NTRS)

    Bilow, N.; Sawko, P.

    1974-01-01

    An investigation was conducted with the objective to improve the hydrolytic stability of reticulated polyurethane baffle material. This material is used in fuel tanks of aircraft and ground vehicles. The most commonly used foam of this type is hydrolytically unstable. Potential moisture barrier coatings which were evaluated include Parylene, epoxy-polysulfide, polyether based polyurethanes, polysulfides, polyolefin rubbers, and several other materials. Parylene coatings of at least 0.2 mil were found to provide the greatest improvement in hydrolytic stability.

  19. Corrosion Resistance Behavior of Single-Layer Cathodic Arc PVD Nitride-Base Coatings in 1M HCl and 3.5 pct NaCl Solutions

    NASA Astrophysics Data System (ADS)

    Adesina, Akeem Yusuf; Gasem, Zuhair M.; Madhan Kumar, Arumugam

    2017-01-01

    The electrochemical behavior of single-layer TiN, CrN, CrAlN, and TiAlN coatings on 304 stainless steel substrate, deposited using state-of-the-art and industrial size cathodic arc PVD machine, were evaluated in 1M HCl and 3.5 pct NaCl solutions. The corrosion behavior of the blank and coated substrates was analyzed by electrochemical impedance spectroscopy (EIS), linear polarization resistance, and potentiodynamic polarization. Bond-coat layers of pure-Ti, pure-Cr, alloyed-CrAl, and alloyed-TiAl for TiN, CrN, CrAlN, and TiAlN coatings were, respectively, first deposited for improved coating adhesion before the actual coating. The average coating thickness was about 1.80 µm. Results showed that the corrosion potentials (E corr) of the coated substrates were shifted to more noble values which indicated improvement of the coated substrate resistance to corrosion susceptibility. The corrosion current densities were lower for all coated substrates as compared to the blank substrate. Similarly, EIS parameters showed that these coatings possessed improved resistance to defects and pores in similar solution compared to the same nitride coatings developed by magnetron sputtering. The charge transfer resistance (R ct) can be ranked in the following order: TiAlN > CrN > TiN > CrAlN in both media except in NaCl solution where R ct of TiN is lowest. While the pore resistance (R po) followed the order: CrAlN > CrN > TiAlN > TiN in HCl solution and TiAlN > CrN > CrAlN > TiN in NaCl solution. It is found that TiAlN coating has the highest protective efficiencies of 79 and 99 pct in 1M HCl and 3.5 pct NaCl, respectively. SEM analysis of the corroded substrates in both media was also presented.

  20. Corrosion Resistance Behavior of Single-Layer Cathodic Arc PVD Nitride-Base Coatings in 1M HCl and 3.5 pct NaCl Solutions

    NASA Astrophysics Data System (ADS)

    Adesina, Akeem Yusuf; Gasem, Zuhair M.; Madhan Kumar, Arumugam

    2017-04-01

    The electrochemical behavior of single-layer TiN, CrN, CrAlN, and TiAlN coatings on 304 stainless steel substrate, deposited using state-of-the-art and industrial size cathodic arc PVD machine, were evaluated in 1M HCl and 3.5 pct NaCl solutions. The corrosion behavior of the blank and coated substrates was analyzed by electrochemical impedance spectroscopy (EIS), linear polarization resistance, and potentiodynamic polarization. Bond-coat layers of pure-Ti, pure-Cr, alloyed-CrAl, and alloyed-TiAl for TiN, CrN, CrAlN, and TiAlN coatings were, respectively, first deposited for improved coating adhesion before the actual coating. The average coating thickness was about 1.80 µm. Results showed that the corrosion potentials ( E corr) of the coated substrates were shifted to more noble values which indicated improvement of the coated substrate resistance to corrosion susceptibility. The corrosion current densities were lower for all coated substrates as compared to the blank substrate. Similarly, EIS parameters showed that these coatings possessed improved resistance to defects and pores in similar solution compared to the same nitride coatings developed by magnetron sputtering. The charge transfer resistance ( R ct) can be ranked in the following order: TiAlN > CrN > TiN > CrAlN in both media except in NaCl solution where R ct of TiN is lowest. While the pore resistance ( R po) followed the order: CrAlN > CrN > TiAlN > TiN in HCl solution and TiAlN > CrN > CrAlN > TiN in NaCl solution. It is found that TiAlN coating has the highest protective efficiencies of 79 and 99 pct in 1M HCl and 3.5 pct NaCl, respectively. SEM analysis of the corroded substrates in both media was also presented.

  1. Formation of structure, phase composition and properties of electro explosion resistant coatings using electron-beam processing

    SciTech Connect

    Romanov, Denis A. E-mail: kos2906@mail.ru E-mail: gromov@physics.sibsiu.ru Sosnin, Kirill V. E-mail: kos2906@mail.ru E-mail: gromov@physics.sibsiu.ru Budovskikh, Evgenij A. E-mail: kos2906@mail.ru E-mail: gromov@physics.sibsiu.ru Gromov, Viktor E. E-mail: kos2906@mail.ru E-mail: gromov@physics.sibsiu.ru Semin, Alexander P. E-mail: kos2906@mail.ru E-mail: gromov@physics.sibsiu.ru

    2014-11-14

    For the first time, the high intensity electron beam modification of electroexplosion composite coatings of MoCu, MoCCu, WCu, WCCu and TiB{sub 2}Cu systems was done. The studies of phase and elemental composition, defective structure conditions of these coatings were carried out. The regimes of electron-beam processing making possible to form the dense, specular luster surface layers having a submicrocrystalline structure were revealed. It was established that electron-beam processing of elecroexplosion spraying of layer of elecroexplosion spraying carried out in the regime of melting results in the formation of structurally and contrationally homogeneous surface layer. Investigation of the effect of electron-beam processing of electroexplosion electroerosion resistant coatings on their tribological properties (wear resistanse and coefficient of friction) and electroerosion resistance was done. It was shown that all the examined costings demonstrate the increase of electroerosion resistance in spark erosion up to 10 times.

  2. Thermal stability and chemical resistance of (Ti,Al)N-Cu and (Ti,Al)N-Ni metal-ceramic nanostructured coatings

    NASA Astrophysics Data System (ADS)

    Belov, D. S.; Blinkov, I. V.; Volkhonskii, A. O.; Kuznetsov, D. V.; Kiryukhantsev-Korneev, F. V.; Pustov, Yu. A.; Sergevnin, V. S.

    2016-12-01

    This work represents the results of research on thermal stability, oxidation resistance at temperatures of up to 800 °C and electrochemical behaviour of (Ti,Al)N-(∼3 at.%)Cu and (Ti,Al)N-(∼8 at.%)Ni nanocrystalline coatings in acidic and alkaline media. The coatings were deposited by the arc-PVD method with a thickness of approximately 4 μm and crystallite size of less than 20 nm. It has been demonstrated that the composition and properties of the coating structures do not change when the coatings are heated in 10-4 Pa vacuum at temperatures of 600, 700 °C for 1.5 h. Heating up to 800 °C caused an increase of crystallite size and reduction microstrain in the crystal lattice of the ceramic phase. The process is accompanied by deterioration of the coating hardness from 48 to 52 to 33-36 GPa. The (Ti,Al)N-Cu and (Ti,Al)N-Ni metal-ceramic nanostructured coatings are characterized by heat resistance up to the temperatures of 700 and 800 °C respectively. The coatings under study have tendency for self-passivation and resistance to pitting corrosion.

  3. Highly Transparent and UV-Resistant Superhydrophobic SiO2-Coated ZnO Nanorod Arrays

    PubMed Central

    2015-01-01

    Highly transparent and UV-resistant superhydrophobic arrays of SiO2-coated ZnO nanorods are prepared in a sequence of low-temperature (<150 °C) steps on both glass and thin sheets of PET (2 × 2 in.2), and the superhydrophobic nanocomposite is shown to have minimal impact on solar cell device performance under AM1.5G illumination. Flexible plastics can serve as front cell and backing materials in the manufacture of flexible displays and solar cells. PMID:24495100

  4. A study on microstructure and corrosion resistance of ZrO2-containing PEO coatings formed on AZ31 Mg alloy in phosphate-based electrolyte

    NASA Astrophysics Data System (ADS)

    Zhuang, J. J.; Guo, Y. Q.; Xiang, N.; Xiong, Y.; Hu, Q.; Song, R. G.

    2015-12-01

    ZrO2-containing ceramic coatings formed on the AZ31 Mg alloy were fabricated in an alkaline electrolyte containing sodium phosphate and potassium fluorozirconate (K2ZrF6) by plasma electrolytic oxidation (PEO). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) techniques were used to study the phase structure and composition of the coatings. It is indicated that the coatings formed in the K2ZrF6-containing electrolyte were composed of MgO, MgF2 and t-ZrO2. Morphological investigation carried out by scanning electron microscopy (SEM) and stereoscopic microscopy, revealed that the uniformity of coatings increased and roughness of coatings decreased after the addition of K2ZrF6. Electrochemical investigation was achieved by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) test. The results showed that the PEO coating formed in K2ZrF6-containing electrolyte exhibited an improved corrosion resistance than that of the coating formed in K2ZrF6-free electrolyte. In addition, the polarization and EIS tests results both showed that the suitable concentration (2.5 g/l) of K2ZrF6 is of significant ability to improve the corrosion resistance of coatings. However, 5 g/l and 10 g/l K2ZrF6 has a negative effect on improving the corrosion resistance of PEO coatings compared with the coating formed in 2.5 g/l K2ZrF6-containing electrolyte.

  5. Electrophoretic Deposition, Microstructure, and Corrosion Resistance of Porous Sol-Gel Glass/Polyetheretherketone Coatings on the Ti-13Nb-13Zr Alloy

    NASA Astrophysics Data System (ADS)

    Moskalewicz, Tomasz; Zych, Anita; Łukaszczyk, Alicja; Cholewa-Kowalska, Katarzyna; Kruk, Adam; Dubiel, Beata; Radziszewska, Agnieszka; Berent, Katarzyna; Gajewska, Marta

    2017-02-01

    In this study, microporous composite sol-gel glass/polyetheretherketone (SGG/PEEK) coatings were produced on the Ti-13Nb-13Zr titanium alloy by electrophoretic deposition. Coatings with different levels of high open porosity were developed by introducing SGG particles of varying diameters into the PEEK matrix. The microstructure of the coatings was characterized by electron microscopy and X-ray diffractometry. The coatings with 40-50 µm thickness were composed of semicrystalline SGG particles consisting of hydroxyapatite, CaSiO3, some Ca2SiO4, and an amorphous phase containing Ca, Si, P, and O, homogeneously embedded in a semicrystalline PEEK matrix. The size of SGG particles present in the coatings strongly influenced the formation of microcracks and their adhesion to the underlying substrate. Microscratch tests showed that the coating containing SGG particles with a diameter smaller than 45 µm and open porosity of 45 pct exhibited good adhesion to the titanium alloy substrate, much better than the coating containing particles with a diameter smaller than 85 µm and total open porosity equal to 48 pct. The corrosion resistance was investigated in Ringer's solution at a temperature of 310 K (37 °C) for a pH equal to 7.4 and in deaerated solutions with the use of open-circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy. The SGG/PEEK-coated alloy indicated better electrochemical corrosion resistance compared with the uncoated alloy.

  6. High-Temperature Oxidation-Resistant and Low Coefficient of Thermal Expansion NiAl-Base Bond Coat Developed for a Turbine Blade Application

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Many critical gas turbine engine components are currently made from Ni-base superalloys that are coated with a thermal barrier coating (TBC). The TBC consists of a ZrO2-based top coat and a bond coat that is used to enhance the bonding between the superalloy substrate and the top coat. MCrAlY alloys (CoCrAlY and NiCrAlY) are currently used as bond coats and are chosen for their very good oxidation resistance. TBC life is frequently limited by the oxidation resistance of the bond coat, along with a thermal expansion mismatch between the metallic bond coat and the ceramic top coat. The aim of this investigation at the NASA Glenn Research Center was to develop a new longer life, higher temperature bond coat by improving both the oxidation resistance and the thermal expansion characteristics of the bond coat. Nickel aluminide (NiAl) has excellent high-temperature oxidation resistance and can sustain a protective Al2O3 scale to longer times and higher temperatures in comparison to MCrAlY alloys. Cryomilling of NiAl results in aluminum nitride (AlN) formation that reduces the coefficient of thermal expansion (CTE) of the alloy and enhances creep strength. Thus, additions of cryomilled NiAl-AlN to CoCrAlY were examined as a potential bond coat. In this work, the composite alloy was investigated as a stand-alone substrate to demonstrate its feasibility prior to actual use as a coating. About 85 percent of prealloyed NiAl and 15 percent of standard commercial CoCrAlY alloys were mixed and cryomilled in an attritor with stainless steel balls used as grinding media. The milling was carried out in the presence of liquid nitrogen. The milled powder was consolidated by hot extrusion or by hot isostatic pressing. From the consolidated material, oxidation coupons, four-point bend, CTE, and tensile specimens were machined. The CTE measurements were made between room temperature and 1000 C in an argon atmosphere. It is shown that the CTE of the NiAl-AlN-CoCrAlY composite bond coat

  7. FY05 HPCRM Annual Report: High-Performance Corrosion-Resistant Iron-Based Amorphous Metal Coatings

    SciTech Connect

    Farmer, J; Choi, J; Haslam, J; Day, S; Yang, N; Headley, T; Lucadamo, G; Yio, J; Chames, J; Gardea, A; Clift, M; Blue, G; Peters, W; Rivard, J; Harper, D; Swank, D; Bayles, R; Lemieux, E; Brown, R; Wolejsza, T; Aprigliano, L; Branagan, D; Marshall, M; Meacham, B; Aprigliano, L; Branagan, D; Marshall, M; Meacham, B; Lavernia, E; Schoenung, J; Ajdelsztajn, L; Dannenberg, J; Graeve, O; Lewandowski, J; Perepezko, J; Hildal, K; Kaufman, L; Boudreau, J

    2007-09-20

    New corrosion-resistant, iron-based amorphous metals have been identified from published data or developed through combinatorial synthesis, and tested to determine their relative corrosion resistance. Many of these materials can be applied as coatings with advanced thermal spray technology. Two compositions have corrosion resistance superior to wrought nickel-based Alloy C-22 (UNS No. N06022) in some very aggressive environments, including concentrated calcium-chloride brines at elevated temperature. Two Fe-based amorphous metal formulations have been found that appear to have corrosion resistance comparable to, or better than that of Ni-based Alloy C-22, based on breakdown potential and corrosion rate. Both Cr and Mo provide corrosion resistance, B enables glass formation, and Y lowers critical cooling rate (CCR). SAM1651 has yttrium added, and has a nominal critical cooling rate of only 80 Kelvin per second, while SAM2X7 (similar to SAM2X5) has no yttrium, and a relatively high critical cooling rate of 610 Kelvin per second. Both amorphous metal formulations have strengths and weaknesses. SAM1651 (yttrium added) has a low critical cooling rate (CCR), which enables it to be rendered as a completely amorphous thermal spray coating. Unfortunately, it is relatively difficult to atomize, with powders being irregular in shape. This causes the powder to be difficult to pneumatically convey during thermal spray deposition. Gas atomized SAM1651 powder has required cryogenic milling to eliminate irregularities that make flow difficult. SAM2X5 (no yttrium) has a high critical cooling rate, which has caused problems associated with devitrification. SAM2X5 can be gas atomized to produce spherical powders of SAM2X5, which enable more facile thermal spray deposition. The reference material, nickel-based Alloy C-22, is an outstanding corrosion-resistant engineering material. Even so, crevice corrosion has been observed with C-22 in hot sodium chloride environments without buffer

  8. Corrosion-resistant coatings for high-temperature high-sulfur- activity applications. Final report

    SciTech Connect

    Selman, J.R.; Aladjov, B.; Chen, B.

    1992-01-01

    The previously started experiments to verify the feasibility of obtaining molybdenum and molybdenum carbide coatings from oxide-based melts were continued. A molten salt bath consisting of an equimolar mixture of Na{sub 2}WO{sub 4} and K{sub 2}WO{sub 4} was used. The molybdenum and carbon species were introduced as alkali molybdate and carbonate. The coating morphology depends strongly on melt composition, temperature and moisture content. Application of initial pre-electrolysis significantly changes the composition and morphology of the coatings. Using non-lithium alkali salts, coatings of better quality were obtained. Adding 3-8 mol% Na{sub 2}B{sub 4}O{sub 7} to the basic non-lithium bath composition was observed to cause significant morphology and quality changes. Bath compositions produce a more uniform small-grain-size coating and they do not require extensive purification. Constant current and reverse and/or pulse current patterns were applied during plating. The latter produces smaller-grain-size coatings at the same working temperature. Research was undertaken to deposit Mo and Mo{sub 2} C films on a substrate 2.5 cm by 3.8 cm in area. Using an orthogonal factorial design, a new series of experiments has been carried out to investigate the effect of the evaporation rate of Mo(CO){sub 6} as a precursor. From the weight gain of the substrate, initial conclusions have been drawn about the optimal conditions for maximum evaporation rate, deposition rate and thickness. Thicker coatings (a few {mu}m) have been obtained which show two different types of crystallites growing on an initially amorphous film. A two dimensional transport and reaction kinetics model for a parallel-plate PECVD reactor was outlined. The PECVD results will be used to verify the model. The primary parameters to be explored are those representing the deposition kinetics of Mo and C.

  9. Corrosion-resistant coatings for high-temperature high-sulfur- activity applications

    SciTech Connect

    Selman, J.R.; Aladjov, B.; Chen, B. . Chemical Engineering Dept.)

    1992-01-01

    The previously started experiments to verify the feasibility of obtaining molybdenum and molybdenum carbide coatings from oxide-based melts were continued. A molten salt bath consisting of an equimolar mixture of Na{sub 2}WO{sub 4} and K{sub 2}WO{sub 4} was used. The molybdenum and carbon species were introduced as alkali molybdate and carbonate. The coating morphology depends strongly on melt composition, temperature and moisture content. Application of initial pre-electrolysis significantly changes the composition and morphology of the coatings. Using non-lithium alkali salts, coatings of better quality were obtained. Adding 3-8 mol% Na{sub 2}B{sub 4}O{sub 7} to the basic non-lithium bath composition was observed to cause significant morphology and quality changes. Bath compositions produce a more uniform small-grain-size coating and they do not require extensive purification. Constant current and reverse and/or pulse current patterns were applied during plating. The latter produces smaller-grain-size coatings at the same working temperature. Research was undertaken to deposit Mo and Mo{sub 2} C films on a substrate 2.5 cm by 3.8 cm in area. Using an orthogonal factorial design, a new series of experiments has been carried out to investigate the effect of the evaporation rate of Mo(CO){sub 6} as a precursor. From the weight gain of the substrate, initial conclusions have been drawn about the optimal conditions for maximum evaporation rate, deposition rate and thickness. Thicker coatings (a few {mu}m) have been obtained which show two different types of crystallites growing on an initially amorphous film. A two dimensional transport and reaction kinetics model for a parallel-plate PECVD reactor was outlined. The PECVD results will be used to verify the model. The primary parameters to be explored are those representing the deposition kinetics of Mo and C.

  10. Leather Coated with Mixtures of Humectant and Antioxidants to Improve UV and Heat Resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ultraviolet (UV) and heat resistance are very important qualities for leather products. We recently developed an environmentally friendly finishing process for improving the UV- and heat resistance of automobile upholstery leather. We previously reported and demonstrated some promising results fro...

  11. Development of improved corrosion- and erosion-resistance coatings for gas-turbine airfoils

    SciTech Connect

    Shen, S.

    1980-01-01

    The main objective of this program is to obtain a ceramic coating with sufficient density to prevent hot-corrosion element diffusion while accommodating the thermal induced stresses and strain encountered in the gas turbine airfoil application. A secondary objective is to include ceramic coatings for outer air seals and combustor components such as falseheads, crossover tubes, and igniters. In addition, these coatings may directly, or with minor modification, be of major interest for insulating diesel engine combustion zones. The application objective is to significantly enhance diesel and gas turbine engine durability when operating with minimally processed alternative fuels. Both steel tabs and IN-738 pins were used as substrate to be coated with Yttria-stabilized Zirconia using EB-PVD technique. Various bond layers including CoCrAlY, NiCrAlY and NiCoCrAlY were also deposited by PVD in a 100 kW coater followed by glass bead peening and vacuum heat-treatment at 1975/sup 0/F for four (4) hours. ZrO/sub 2/(Y/sub 2/O/sub 3/) top layers were deposited in a 200 kW coater with a pressure barrier system to enable oxygen gas being introduced during the coating process. Results are presented and discussed. (WHK)

  12. Evaluating the Thermal Damage Resistance of Reduced Graphene Oxide/Carbon Nanotube Hybrid Coatings

    NASA Astrophysics Data System (ADS)

    David, Lamuel; Feldman, Ari; Mansfield, Elisabeth; Lehman, John; Singh, Gurpreet; National Institute of Standards and Technology Collaboration

    2014-03-01

    Carbon nanotubes and graphene are known to exhibit some exceptional thermal (K ~ 2000 to 4400 W.m-1K-1 at 300K) and optical properties. Here, we demonstrate preparation and testing of multiwalled carbon nanotubes and chemically modified graphene-composite spray coatings for use on thermal detectors for high-power lasers. The synthesized nanocomposite material was tested by preparing spray coatings on aluminum test coupons used as a representation of the thermal detector's surface. These coatings were then exposed to increasing laser powers and extended exposure times to quantify their damage threshold and optical absorbance. The graphene/carbon nanotube (prepared at varying mass% of graphene in CNTs) coatings demonstrated significantly higher damage threshold values at 2.5 kW laser power (10.6 μm wavelength) than carbon paint or MWCNTs alone. Electron microscopy and Raman spectroscopy of irradiated specimens showed that the composite coating endured high laser-power densities (up to 2 kW.cm-2) without significant visual damage. This research is based on work supported by the National Science Foundation (Chemical, Bioengineering, Environmental, and Transport Systems Division), under grant no. 1335862 to G. Singh.

  13. Investigation of Oxidation-Resistant Coatings on Graphite and Molybdenum in Two Arc-Powered Facilities

    NASA Technical Reports Server (NTRS)

    Peters, Roger W.; Rasnick, Thomas A.

    1961-01-01

    A number of leading-edge specimens of ATJ graphite and 0.5-percent titanium-molybdenum alloy were tested in a 6-inch subsonic low-pressure arc-powered tunnel and a 1,500-kw subsonic arc jet to determine the effectiveness of several refractory coatings in preventing the oxidation of these materials. The results indicate that the siliconized coating for the ATJ graphite and the W-2 and Durak MG coatings for the titanium-molybdenum alloy provide adequate protection at temperatures up to 3,000 F for the durations of the tests in these facilities, approximately 70 seconds in the arc tunnel and approximately 10 minutes in the arc jet. Weight losses (less than one-half of 1 percent) experienced by a few of the coated specimens indicate that tests of longer duration in these environments may prove deleterious and that the stability of these coatings may be depreciated under the low-pressure environmental conditions encountered during reentry.

  14. The effect of nitrogen ion implantation on the corrosion resistance and microstructure of tantalum-coated stainless steel

    NASA Astrophysics Data System (ADS)

    Eshghi, S.; Hanteh Zadeh, M.; Yari, M.; Jafari-Khamse, E.

    2014-06-01

    In this work, the effects of nitrogen ion implantation on the corrosion resistance and microstructure of DC magnetron sputtered tantalum-coated stainless steel were investigated. The nitrogen fluence was varied between 3-10 × 1017 ions/cm2 while the beam energy was kept constant at 30 keV. The effects of ion implantation were characterized by X-ray diffraction pattern, atomic force microscopy, and potentiodynamic corrosion test in a 0.5 MH2SO4 solution. The atomic force microscopy micrographs were quantitatively and statistically analyzed by computing the multifractal spectrum of the atomic force microscopy images. The results showed that the fluence variation strongly affected the surface roughness and formation of TaN and Ta2N phases. Increasing the nitrogen fluence up to 10 × 1017 ions/cm2 increased surface roughness. The highest corrosion resistance was obtained at 7 × 1017 ions/cm2 nitrogen fluence.

  15. Optimizing structural and compositional properties of electrodeposited ceria coatings for enhanced oxidation resistance of a nickel-based superalloy

    NASA Astrophysics Data System (ADS)

    Bouchaud, B.; Balmain, J.; Bonnet, G.; Pedraza, F.

    2013-03-01

    Cathodic electrodeposition was used to generate ceria coatings onto a Ni-based superalloy substrate. The electrochemical parameters were optimized so as to obtain relatively thick but adherent films with tailored composition and microstructural features (multi-cracked network) designed for high temperature applications. Whereas the applied current density was shown to mainly influence the appearance and size of the cracks as well as the amount of oxygen vacancies, the linear trend between the deposited mass and the deposition time allowed a good control of the deposited thickness. A crystallization/diffusion thermal treatment was then applied to promote the dehydration of the deposit, thus resulting in a network of refined cracks, and in the complete crystallization of nanometric CeO2-x exhibiting either a needle-like or a quasi "foam-like" microstructure depending on the applied temperature. This also provided the establishment of an inwardly grown α-Al2O3 scale at the substrate/coating interface expected to further increase the high temperature oxidation resistance of the coated superalloy.

  16. Total electron scattering cross section of Fluorocarbons at intermediate electron energies

    NASA Astrophysics Data System (ADS)

    Palihawadana, Prasanga; Villela, Gilberto; Ariyasinghe, Wickramasinghe

    2008-10-01

    Total electron scattering cross sections (TCS) of Tetrafluoromethane (CF4), Trifluoromethane (CHF3), Hexafluoroethane (C2F6) and Octafluorocyclobutane (C4F8) have been measured using the linear transmission technique for impact energies 0.10 -- 4.00 keV. These TCS are compared to existing experimental and theoretical TCS in the literature. Based on the present measurements, an empirical formula is developed to predict the TCS of fluorocarbons as a function of incident electron energy.

  17. Wettability of polymeric solids by ternary mixtures composed of hydrocarbon and fluorocarbon nonionic surfactants.

    PubMed

    Szymczyk, Katarzyna

    2011-11-01

    Contact angle (θ) measurements on poly(tetrafluoroethylene) (PTFE) and polymethyl methacrylate (PMMA) surface were carried out for the systems containing ternary mixtures of surfactants composed of: p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycols), Triton X-100 (TX100), Triton X-165 (TX165) and Triton X-114 (TX114), and fluorocarbon surfactants, Zonyl FSN100 (FSN100) and Zonyl FSO100 (FSO100). The aqueous solutions of ternary surfactant mixtures were prepared by adding TX114, FSN100 or FSO100 to binary mixtures of TX100+TX165, where the synergistic effect in the reduction of the surface tension of water (γ(LV)) was determined. From the obtained contact angle values, the relationships between cosθ, the adhesion tension and surface tension of solutions, cosθ and the reciprocal of the surface tension were determined. On the basis of these relationships, the correlation between the critical surface tension of PTFE and PMMA wetting and the surface tension of these polymers as well as the work of adhesion of aqueous solutions of ternary surfactant mixtures to PTFE and PMMA surface were discussed. The critical surface tension of PTFE and PMMA wetting, γ(C), determined from the contact angle measurements of aqueous solutions of surfactants including FSN100 or FSO100 was also discussed in the light of the surface tension changes of PTFE and PMMA under the influence of film formation by fluorocarbon surfactants on the surface of these polymers. The γ(C) values of the studied polymeric solids were found to be different for the mixtures composed of hydrocarbon surfactants in comparison with those of hydrocarbon and fluorocarbon surfactants. In the solutions containing fluorocarbon surfactants, the γ(C) values were different taking into account the contact angle in the range of FSN100 and FSO100 concentration corresponding to their unsaturated monolayer at water-air interface or to that saturated.

  18. The Effect of Fluorocarbon Surfactant Additives on the Effective Viscosity of Acetone Solutions of Cellulose Diacetate,

    DTIC Science & Technology

    2014-09-26

    34 FOREIGN TECHNOLOGY DIVISION i00 Lfl .. THE EFFECT OF FLUOROCARBON SURFACTANT ADDITIVES ON THE EFFECTIVE VISCOSITY OF ACETONE SOLUTIONS OF CELLULOSE...ADDITIVES ON TH~ .. t- ’_ ition EFFECTIVE VISCOSITY OF ACETONE SOLUTIONS OF CELLULOSE DIACETATE D~rbt~l By: L.A. Shits, N. Yu. Kal’nova Codesuton English...VISCOSITY OF ACETONE SOLUTIONS OF CELLULOSE DIACETATE L. A. Shits, N. Yu. Kal’nova (Institute of Physical Chemistry of the AS USSR, Moscow) ! - The

  19. Superior Corrosion Resistance Properties of TiN-Based Coatings on Zircaloy Tubes in Supercritical Water

    SciTech Connect

    Fauzia Khatkhatay; Liang Jiao; Jie Jian; Zhijie Jiao; Hongbin Zhang; Jian Gan; Haiyan Wang; Wenrui Zhang; Xinghang Zhang

    2014-08-01

    Thin films of TiN and Ti0.35Al0.65N nanocomposite were deposited on polished Zircaloy-4 tubes. After exposure to supercritical water for 48 h, the coated tubes are remarkably intact, while the bare uncoated tube shows severe oxidation and breakaway corrosion. X-ray diffraction patterns, secondary electron images, backscattered electron images, and energy dispersive X-ray spectroscopy data from the tube surfaces and cross-sections show that a protective oxide, formed on the film surface, effectively prevents further oxidation and corrosion to the Zircaloy-4 tubes. This result demonstrates the effectiveness of thin film ceramics as protective coatings under extreme environments.

  20. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Huang, Yiqin; Li, Heqin; Zuo, Min; Tao, Lei; Wang, Wei; Zhang, Jing; Tang, Qiong; Bai, Peiwen

    2016-07-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB.