Science.gov

Sample records for active coating process

  1. Modeling of an Active Tablet Coating Process.

    PubMed

    Toschkoff, Gregor; Just, Sarah; Knop, Klaus; Kleinebudde, Peter; Funke, Adrian; Djuric, Dejan; Scharrer, Georg; Khinast, Johannes G

    2015-12-01

    Tablet coating is a common unit operation in the pharmaceutical industry, during which a coating layer is applied to tablet cores. The coating uniformity of tablets in a batch is especially critical for active coating, that is, coating that contains an active pharmaceutical ingredient. In recent years, discrete element method (DEM) simulations became increasingly common for investigating tablet coating. In this work, DEM was applied to model an active coating process as closely as possible, using measured model parameters and non-spherical particles. We studied how operational conditions (rotation speed, fill level, number of nozzles, and spray rate) influence the coating uniformity. To this end, simulation runs were planned and interpreted according to a statistical design of (simulation) experiments. Our general goal was to achieve a deeper understanding of the process in terms of residence times and dimensionless scaling laws. With that regard, the results were interpreted in light of analytical models. The results were presented at various detail levels, ranging from an overview of all variations to in-depth considerations. It was determined that the biggest uniformity improvement in a realistic setting was achieved by increasing the number of spray nozzles, followed by increasing the rotation speed and decreasing the fill level.

  2. An evaluation of process parameters to improve coating efficiency of an active tablet film-coating process.

    PubMed

    Wang, Jennifer; Hemenway, Jeffrey; Chen, Wei; Desai, Divyakant; Early, William; Paruchuri, Srinivasa; Chang, Shih-Ying; Stamato, Howard; Varia, Sailesh

    2012-05-10

    Effects of material and manufacturing process parameters on the efficiency of an aqueous active tablet film-coating process in a perforated pan coater were evaluated. Twenty-four batches representing various core tablet weights, sizes, and shapes were coated at the 350-500 kg scale. The coating process efficiency, defined as the ratio of the amount of active deposited on tablet cores to the amount of active sprayed, ranged from 86 to 99%. Droplet size and velocity of the coating spray were important for an efficient coating process. Factors governing them such as high ratios of the suspension spray rate to atomization air flow rate, suspension spray rate to pattern air flow rate, or atomization air flow rate to pattern air flow rate improved the coating efficiency. Computational fluid dynamics modeling of the droplets showed that reducing the fraction of the smaller droplets, especially those smaller than 10 μm, resulted in a marked improvement in the coating efficiency. Other material and process variables such as coating suspension solids concentration, pan speed, tablet velocity, exhaust air temperature, and the length of coating time did not affect the coating efficiency profoundly over the ranges examined here.

  3. Antibacterial activity of plastics coated with silver-doped organic-inorganic hybrid coatings prepared by sol-gel processes.

    PubMed

    Marini, M; De Niederhausern, S; Iseppi, R; Bondi, M; Sabia, C; Toselli, M; Pilati, F

    2007-04-01

    Silver-doped organic-inorganic hybrid coatings were prepared starting from tetraethoxysilane- and triethoxysilane-terminated poly(ethylene glycol)-block-polyethylene by the sol-gel process. They were applied as a thin layer (0.6-1.1 microm) to polyethylene (PE) and poly(vinyl chloride) (PVC) films and the antibacterial activity of the coated films was tested against Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538) bacteria. The effect of several factors (such as organic-inorganic ratio, type of catalyst, time of post-curing, silver ion concentration, etc.) was investigated. Measurements at different contact times showed a rapid decrease of the viable count for both tested strains. The highest antibacterial activity [more than 6 log reduction within 6 h starting from 106 colony-forming units (cfu) mL-1] was obtained for samples with an organic-inorganic weight ratio of 80:20 and 5 wt % silver salt with respect to the coating. For the coatings prepared by an acid-catalyzed process, a high level of permanence of the antibacterial activity of the coated films was demonstrated by repeatedly washing the samples in warm water or by immersion in physiological saline solution at 37 degrees C for 3 days. The release of silver ions per square meter of coating is very similar to that previously observed for polyamides filled with metallic silver nanoparticles; however, when compared on the basis of Ag content, the concentration of silver ions released from the coating is much higher than that released from 1 mm thick specimens of polyamide (PA) filled with silver nanoparticles. Transparency and good adhesion of the coating to PE and PVC plastic substrates without any previous surface treatment are further interesting features.

  4. Experimental analysis of tablet properties for discrete element modeling of an active coating process.

    PubMed

    Just, Sarah; Toschkoff, Gregor; Funke, Adrian; Djuric, Dejan; Scharrer, Georg; Khinast, Johannes; Knop, Klaus; Kleinebudde, Peter

    2013-03-01

    Coating of solid dosage forms is an important unit operation in the pharmaceutical industry. In recent years, numerical simulations of drug manufacturing processes have been gaining interest as process analytical technology tools. The discrete element method (DEM) in particular is suitable to model tablet-coating processes. For the development of accurate simulations, information on the material properties of the tablets is required. In this study, the mechanical parameters Young's modulus, coefficient of restitution (CoR), and coefficients of friction (CoF) of gastrointestinal therapeutic systems (GITS) and of active-coated GITS were measured experimentally. The dynamic angle of repose of these tablets in a drum coater was investigated to revise the CoF. The resulting values were used as input data in DEM simulations to compare simulation and experiment. A mean value of Young's modulus of 31.9 MPa was determined by the uniaxial compression test. The CoR was found to be 0.78. For both tablet-steel and tablet-tablet friction, active-coated GITS showed a higher CoF compared with GITS. According to the values of the dynamic angle of repose, the CoF was adjusted to obtain consistent tablet motion in the simulation and in the experiment. On the basis of this experimental characterization, mechanical parameters are integrated into DEM simulation programs to perform numerical analysis of coating processes.

  5. Coated substrates and process

    DOEpatents

    Chu, Wei-kan; Childs, Charles B.

    1991-01-01

    Disclosed herein is a coated substrate and a process for forming films on substrates and for providing a particularly smooth film on a substrate. The method of this invention involves subjecting a surface of a substrate to contact with a stream of ions of an inert gas having sufficient force and energy to substantially change the surface characteristics of said substrate, and then exposing a film-forming material to a stream of ions of an inert gas having sufficient energy to vaporize the atoms of said film-forming material and to transmit the vaporized atoms to the substrate surface with sufficient force to form a film bonded to the substrate. This process is particularly useful commercially because it forms strong bonds at room temperature. This invention is particularly useful for adhering a gold film to diamond and forming ohmic electrodes on diamond, but also can be used to bond other films to substrates.

  6. Waterjet processes for coating removal

    NASA Technical Reports Server (NTRS)

    Burgess, Fletcher; Cosby, Steve; Hoppe, David

    1995-01-01

    USBI and NASA have been testing and investigating the use of high pressure water for coating removal for approximately the past 12 years at the Automated TPS (Thermal Protection System - ablative materials used for thermal protection during ascent and descent of the solid rocket boosters) Removal Facility located in the Productivity Enhancement Complex at Marshall Space Flight Center. Originally the task was to develop and automate the removal process and transfer the technology to a production facility at Kennedy Space Center. Since that time more and more applications and support roles for the waterjet technology have been realized. The facility has become a vital part of development activities ongoing at MSFC. It supports the development of environmentally compliant insulations, sealants, and coatings. It also supports bonding programs, test motors, and pressure vessels. The most recent role of the cell is supporting Thiokol Corporation's solid rocket motor program in the development of waterjet degreasing and paint stripping methods. Currently vapor degreasing methods use 500,000 lbs. of ozone depleting chemicals per year. This paper describes the major cell equipment, test methods practiced, and coatings that have been removed.

  7. PROCESS FOR REMOVING ALUMINUM COATINGS

    DOEpatents

    Flox, J.

    1959-07-01

    A process is presented for removing aluminum jackets or cans from uranium slugs. This is accomplished by immersing the aluminum coated uranium slugs in an aqueous solution of 9 to 20% sodium hydroxide and 35 to 12% sodium nitrate to selectively dissolve the aluminum coating, the amount of solution being such as to obtain a molar ratio of sodium hydroxide to aluminum of at least

  8. Electrocurtain coating process for coating solar mirrors

    DOEpatents

    Kabagambe, Benjamin; Boyd, Donald W.; Buchanan, Michael J.; Kelly, Patrick; Kutilek, Luke A.; McCamy, James W.; McPheron, Douglas A.; Orosz, Gary R.; Limbacher, Raymond D.

    2013-10-15

    An electrically conductive protective coating or film is provided over the surface of a reflective coating of a solar mirror by flowing or directing a cation containing liquid and an anion containing liquid onto the conductive surface. The cation and the anion containing liquids are spaced from, and preferably out of contact with one another on the surface of the reflective coating as an electric current is moved through the anion containing liquid, the conductive surface between the liquids and the cation containing liquid to coat the conductive surface with the electrically conductive coating.

  9. Evolution of aluminide coating microstructure on nickel-base cast superalloy CM-247 in a single-step high-activity aluminizing process

    SciTech Connect

    Das, D.K.; Joshi, S.V.; Singh, V.

    1998-08-01

    This study deals with the aluminizing of a directionally cast Ni-base superalloy, namely CM-247, by a single-step process using a high-activity pack. It is observed that significant incorporation of Al into the substrate surface during aluminizing continues over a period of about 1 hour and is not restricted merely to the first few minutes, as reported in the literature. Based on the microstructural details of the coatings formed at various stages of aluminizing, it is concluded that the coating growth in the above process takes place primarily by inward Al diffusion initially, followed by an intermediate stage when the growth involves both inward Al and outward Ni diffusion. In the final stages, the outward diffusion of Ni dominates the coating formation process. The above mechanism of coating formation is different from the one that prevails in the conventional two-step high-activity coating process in that the reaction front for the formation of NiAl remains spatially stationary despite the outward diffusion of nickel during the intermediate stage. It is also shown in the present study that the content of the Al source in the pack affects the coating structure significantly. It is further demonstrated that the microstructure of the aluminide coatings depends not only on the amount of Al incorporated in the sample during aluminizing but also on the time over which the uptake of this Al takes place.

  10. Electrophoretically active sol-gel processes to backfill, seal, and/or densify porous, flawed, and/or cracked coatings on electrically conductive material

    DOEpatents

    Panitz, Janda K.; Reed, Scott T.; Ashley, Carol S.; Neiser, Richard A.; Moffatt, William C.

    1999-01-01

    Electrophoretically active sol-gel processes to fill, seal, and/or density porous, flawed, and/or cracked coatings on electrically conductive substrates. Such coatings may be dielectrics, ceramics, or semiconductors and, by the present invention, may have deposited onto and into them sol-gel ceramic precursor compounds which are subsequently converted to sol-gel ceramics to yield composite materials with various tailored properties.

  11. Electrophoretically active sol-gel processes to backfill, seal, and/or densify porous, flawed, and/or cracked coatings on electrically conductive material

    DOEpatents

    Panitz, J.K.; Reed, S.T.; Ashley, C.S.; Neiser, R.A.; Moffatt, W.C.

    1999-07-20

    Electrophoretically active sol-gel processes to fill, seal, and/or density porous, flawed, and/or cracked coatings on electrically conductive substrates. Such coatings may be dielectrics, ceramics, or semiconductors and, by the present invention, may have deposited onto and into them sol-gel ceramic precursor compounds which are subsequently converted to sol-gel ceramics to yield composite materials with various tailored properties. 6 figs.

  12. Synergistic Effect of Sodium Chlorite and Edible Coating on Quality Maintenance of Minimally Processed Citrus grandis under Passive and Active MAP.

    PubMed

    Ban, Zhaojun; Feng, Jianhua; Wei, Wenwen; Yang, Xiangzheng; Li, Jilan; Guan, Junfeng; Li, Jiang

    2015-08-01

    Edible coating has been an innovation within the bioactive packaging concept. The comparative analysis upon the effect of edible coating, sodium chlorite (SC) and their combined application on quality maintenance of minimally processed pomelo (Citrus grandis) fruits during storage at 4 °C was conducted. Results showed that the combination of edible coating and SC dipping delayed the microbial development whereas the sole coating or dipping treatment was less efficient. The synergetic application of edible coating and SC treatment under modified atmosphere packaging (MAP, 10% O2 , 10% CO2 ) was able to maintain the total soluble solids level and ascorbic acid content, while reduce the weight loss as well as development of mesophiles and psychrotrophs. Nonetheless, the N, O-carboxymethyl chitosan solely coated samples showed significantly higher level of weight loss during storage with comparison to the untreated sample. Furthermore, the combined application of edible coating and SC dipping under active MAP best maintained the sensory quality of minimally processed pomelo fruit during storage.

  13. Sputtering process and apparatus for coating powders

    DOEpatents

    Makowiecki, Daniel M.; Kerns, John A.; Alford, Craig S.; McKernan, Mark A.

    2002-01-01

    A process and apparatus for coating small particles and fibers. The process involves agitation by vibrating or tumbling the particles or fibers to promote coating uniformly, removing adsorbed gases and static charges from the particles or fibers by an initial plasma cleaning, and coating the particles or fibers with one or more coatings, a first coating being an adhesion coating, and with subsequent coatings being deposited in-situ to prevent contamination at layer interfaces. The first coating is of an adhesion forming element (i.e. W, Zr, Re, Cr, Ti) of a 100-10,000 .ANG. thickness and the second coating or final coating of a multiple (0.1-10 microns) being Cu or Ag, for example for brazing processes, or other desired materials that defines the new surface related properties of the particles. An essential feature of the coating process is the capability to deposit in-situ without interruption to prevent the formation of a contaminated interface that could adversely affect the coating adhesion. The process may include screening of the material to be coated and either continuous or intermittent vibration to prevent agglomeration of the material to be coated.

  14. 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.

  15. PLA coated paper containing active inorganic nanoparticles: Material characterization and fate of nanoparticles in the paper recycling process.

    PubMed

    Zhang, Hai; Bussini, Daniele; Hortal, Mercedes; Elegir, Graziano; Mendes, Joana; Jordá Beneyto, Maria

    2016-06-01

    For paper and paperboard packaging, recyclability plays an important role in conserving the resources and reducing the environmental impacts. Therefore, when it comes to the nano-enabled paper packaging material, the recyclability issue should be properly addressed. This study represents our first report on the fate of nanomaterials in paper recycling process. The packaging material of concern is a PLA (Polylactic Acid) coated paper incorporating zinc oxide nanoparticles in the coating layer. The material was characterised and assessed in a lab-scale paper recycling line. The recyclability test was based on a method adapted from ATICELCA MC501-13, which enabled to recover over 99% of the solids material. The mass balance result indicates that 86-91% zinc oxide nanoparticles ended up in the rejected material stream, mostly embedded within the polymer coating; whereas 7-16% nanoparticles ended up in the accepted material stream. Besides, the tensile strength of the recycled handsheets suggests that the nano-enabled coating had no negative impacts on the recovered fibre quality.

  16. A New Coating Process for Production of Coated Magnesium Powders

    DTIC Science & Technology

    2008-04-16

    TGA data for magnesium hydroxide content. TGA analysis of the as-coated powders is a reproducible and accurate method for the determination of... TGA analysis of the as-coated powder, there is approximately 3wt% magnesium hydroxide present in the material due to the process variation compared...11: Magnesium hydroxide content as measured by TGA analysis for the 1-lb batches of as-coated ground powder Figure 12: Nitrometer analysis of

  17. Evaluation of Chemical Coating Processes for AXAF

    NASA Technical Reports Server (NTRS)

    Engelhaupt, Darell; Ramsey, Brian; Mendrek, Mitchell

    1998-01-01

    The need existed at MSFC for the development and fabrication of radioisotope calibration sources of cadmium 109 and iron 55 isotopes. This was in urgent response to the AXA-F program. Several issues persisted in creating manufacturing difficulties for the supplier. In order to meet the MSFC requirements very stringent control needed to be maintained for the coating quality, specific activity and thickness. Due to the difficulties in providing the precisely controlled devices for testing, the delivery of the sources was seriously delayed. It became imperative that these fabrication issues be resolved to avoid further delays in this AXA-F observatory key component. The objectives are: 1) Research and provide expert advice on coating materials and procedures. 2) Research and recommend solutions to problems that have been experienced with the coating process. 3) Provide recommendations on the selection and preparation of substrates. 4) Provide consultation on the actual coating process including the results of the qualification and acceptance test programs. 5) Perform independent tests at UAH or MSFC as necessary.

  18. Active coatings technologies for tailorable military coating systems

    NASA Astrophysics Data System (ADS)

    Zunino, J. L., III

    2007-04-01

    The main objective of the U.S. Army's Active Coatings Technologies Program is to develop technologies that can be used in combination to tailor coatings for utilization on Army Materiel. The Active Coatings Technologies Program, ACT, is divided into several thrusts, including the Smart Coatings Materiel Program, Munitions Coatings Technologies, Active Sensor packages, Systems Health Monitoring, Novel Technology Development, as well as other advanced technologies. The goal of the ACT Program is to conduct research leading to the development of multiple coatings systems for use on various military platforms, incorporating unique properties such as self repair, selective removal, corrosion resistance, sensing, ability to modify coatings' physical properties, colorizing, and alerting logistics staff when tanks or weaponry require more extensive repair. A partnership between the U.S. Army Corrosion Office at Picatinny Arsenal, NJ along with researchers at the New Jersey Institute of Technology, NJ, Clemson University, SC, University of New Hampshire, NH, and University of Massachusetts (Lowell), MA, are developing the next generation of Smart Coatings Materiel via novel technologies such as nanotechnology, Micro-electromechanical Systems (MEMS), meta-materials, flexible electronics, electrochromics, electroluminescence, etc. This paper will provide the reader with an overview of the Active Coatings Technologies Program, including an update of the on-going Smart Coatings Materiel Program, its progress thus far, description of the prototype Smart Coatings Systems and research tasks as well as future nanotechnology concepts, and applications for the Department of Defense.

  19. Chemical Processing of Nanostructured Coatings

    DTIC Science & Technology

    2000-01-01

    synthesis conditions, coatings, porous solids, powders, fibers, bulk materials may be prepared. From solution, coatings may be applied to a substrate, or...fibers may be drawn if the viscosity of the sol is high enough. If the sol is allowed to start to gel, a porous solid or a powder can be formed from...the gel. The porous solid or nanopowder can also be used as a starting material for some coating techniques. There are many types of sol-gel coatings

  20. Electrical contact arrangement for a coating process

    DOEpatents

    Kabagambe, Benjamin; McCamy, James W; Boyd, Donald W

    2013-09-17

    A protective coating is applied to the electrically conductive surface of a reflective coating of a solar mirror by biasing a conductive member having a layer of a malleable electrically conductive material, e.g. a paste, against a portion of the conductive surface while moving an electrodepositable coating composition over the conductive surface. The moving of the electrodepositable coating composition over the conductive surface includes moving the solar mirror through a flow curtain of the electrodepositable coating composition and submerging the solar mirror in a pool of the electrodepositable coating composition. The use of the layer of a malleable electrically conductive material between the conductive member and the conductive surface compensates for irregularities in the conductive surface being contacted during the coating process thereby reducing the current density at the electrical contact area.

  1. Nanoengineered Additives for Active Coatings

    DTIC Science & Technology

    2007-04-01

    commercial ad bial activ component from the coating, leading to eventual depletion of the film. Small TPU samples were evaluated using a Kirby - Bauer ...7 Table 5. Summary of 24-hr ASTM E 2180 tests with 1 weight-percent additive in PUr (solvent dispersible) based on 6-log loading of...Noveon X-1150). The ASTM E 2180 test is run in triplicate (Note that alternative ro 1° amines) was suspended in dry tetrahydrofuran (THF) (150 mL) in

  2. Wear Performance of Laser Processed Tantalum Coatings

    PubMed Central

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

    2011-01-01

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

  3. Mathematical modeling of the coating process.

    PubMed

    Toschkoff, Gregor; Khinast, Johannes G

    2013-12-05

    Coating of tablets is a common unit operation in the pharmaceutical industry. In most cases, the final product must meet strict quality requirements; to meet them, a detailed understanding of the coating process is required. To this end, numerous experiment studies have been performed. However, to acquire a mechanistic understanding, experimental data must be interpreted in the light of mathematical models. In recent years, a combination of analytical modeling and computational simulations enabled deeper insights into the nature of the coating process. This paper presents an overview of modeling and simulation approaches of the coating process, covering various relevant aspects from scale-up considerations to coating mass uniformity investigations and models for drop atomization. The most important analytical and computational concepts are presented and the findings are compared.

  4. Thermal Imaging Processes of Polymer Nanocomposite Coatings

    NASA Astrophysics Data System (ADS)

    Meth, Jeffrey

    2015-03-01

    Laser induced thermal imaging (LITI) is a process whereby infrared radiation impinging on a coating on a donor film transfers that coating to a receiving film to produce a pattern. This talk describes how LITI patterning can print color filters for liquid crystal displays, and details the physical processes that are responsible for transferring the nanocomposite coating in a coherent manner that does not degrade its optical properties. Unique features of this process involve heating rates of 107 K/s, and cooling rates of 104 K/s, which implies that not all of the relaxation modes of the polymer are accessed during the imaging process. On the microsecond time scale, the polymer flow is forced by devolatilization of solvents, followed by deformation akin to the constrained blister test, and then fracture caused by differential thermal expansion. The unique combination of disparate physical processes demonstrates the gamut of physics that contribute to advanced material processing in an industrial setting.

  5. Process for Coating Substrates with Catalytic Materials

    NASA Technical Reports Server (NTRS)

    Klelin, Ric J. (Inventor); Upchurch, Billy T. (Inventor); Schryer, David R. (Inventor)

    2004-01-01

    A process for forming catalysts by coating substrates with two or more catalytic components, which comprises the following sequence of steps. First, the substrate is infused with an adequate amount of solution having a starting material comprising a catalytic component precursor, wherein the thermal decomposition product of the catalytic component precursor is a catalytic component. Second, the excess of the solution is removed from the substrate. thereby leaving a coating of the catalytic component precursor on the surface of the substrate. Third, the coating of the catalytic component precursor is converted to the catalytic component by thermal decomposition. Finally, the coated substance is etched to increase the surface area. The list three steps are then repeated for at least a second catalytic component. This process is ideally suited for application in producing efficient low temperature oxidation catalysts.

  6. Convergent spray process for environmentally friendly coatings

    NASA Technical Reports Server (NTRS)

    Scarpa, Jack

    1995-01-01

    Conventional spray application processes have poor transfer efficiencies, resulting in an exorbitant loss in materials, solvents, and time. Also, with ever tightening Environmental Protection Agency (EPA) regulations and Occupational Safety and Health Administration requirements, the low transfer efficiencies have a significant impact on the quantities of materials and solvents that are released into the environment. High solids spray processes are also limited by material viscosities, thus requiring many passes over the surface to achieve a thickness in the 0.125 -inch range. This results in high application costs and a negative impact on the environment. Until recently, requirements for a 100 percent solid sprayable, environmentally friendly, lightweight thermal protection system that can be applied in a thick (greater than 0.125 inch) single-pass operation exceeded the capability of existing systems. Such coatings must be applied by hand lay-up techniques, especially for thermal and/or fire protection systems. The current formulation of these coatings has presented many problems such as worker safety, environmental hazards, waste, high cost, and application constraints. A system which can apply coatings without using hazardous materials would alleviate many of these problems. Potential applications include the aerospace thermal protective specialty coatings, chemical and petroleum industries that require fire-protection coatings that resist impact, chemicals, and weather. These markets can be penetrated by offering customized coatings applied by automated processes that are environmentally friendly.

  7. A parylene coating process for hybrid circuits

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The parylene coating process developed during this program consists of (1) obtaining a hybrid cover with a hole in it, (2) sealing of the circuit with a hole in the cover, (3) parylene coating through the hole with the external leads protected from parylene by appropriate fixturing, and (4) sealing of the hole by soldering a pretinned kovar tab. Development of the above process required optimization of the parylene coater parameters to obtain a uniform consistent coating which could offer adequate protection to the circuits, fixture design for packages of various types, determination of the size of the deposition hole, and the amount of dimer charge per run, a process to hermetically seal the deposition holes and establishment of quality control techniques or acceptance criteria for the deposited film.

  8. Process to minimize cracking of pyrolytic carbon coatings

    DOEpatents

    Lackey, Jr., Walter J.; Sease, John D.

    1978-01-01

    Carbon-coated microspheroids useful as fuels in nuclear reactors are produced with a low percentage of cracked coatings and are imparted increased strength and mechanical stability characteristics by annealing immediately after the carbon coating processes.

  9. Method to produce catalytically active nanocomposite coatings

    DOEpatents

    Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa; Kazmanli, Kursat

    2016-02-09

    A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

  10. Building quality into a coating process.

    PubMed

    Naelapää, Kaisa; Veski, Peep; Kristensen, Henning Gjelstrup; Rantanen, Jukka; Bertelsen, Poul

    2010-01-01

    An effective approach towards optimal development strategy is to use the quality by design principle. However, this approach can first be implemented when possible risks impacting critical quality attributes are defined and interactions between those are fully understood. The objective of this study was to identify critical variables that affect the final modified release product performance using a risk management approach with supporting statistical tool. After risk ranking and filtering a full mixed factorial experimental design of coating experiments was performed. Experimental design clearly indicated that studied critical processes parameters have a great impact on coat integrity and hence on drug release.

  11. Photonic properties of erbium activated coated microspheres

    NASA Astrophysics Data System (ADS)

    Jestin, Y.; Armellini, C.; Chiappini, A.; Chiasera, A.; Dumeige, Y.; Ferrari, M.; Féron, P.; Ghisa, L.; Nunzi Conti, G.; Trebaol, S.; Righini, G. C.

    2008-02-01

    μA simple method based on the sol-gel technology has been developed to coat passive microspheres with an active coating. The microspheres were prepared by fusion of a standard telecom fiber with a dimension of about 200 μm and 400 μm and have been respectively dipped in a 70SiO II-30HfO II sol activated by 1 mol% and 0.1 mol% of erbium ions. Here we first report about the luminescence properties of a silica-hafnia coating doped with erbium ions and then whispering gallery mode spectra were analysed for different sphere diameters, thickness of coating and erbium concentration. The thickness of the coating has been chosen in order to support at least one whispering gallery mode at 1.5 μm.

  12. Processing of fused silicide coatings for carbon-based materials

    NASA Technical Reports Server (NTRS)

    Smialek, J. L.

    1982-01-01

    The processing and oxidation resistance of fused Al-Si and Ni-Si slurry coatings on ATJ graphite was studied. Ni-Si coatings in the 70 to 90 percent Si range were successfully processed to melt, wet, and bond to the graphite. The molten coatings also infiltrated the porosity in graphite and reacted with it to form SiC in the coating. Cyclic oxidation at 1200 C showed that these coatings were not totally protective because of local attack of the substrate, due to the extreme thinness of the coatings in combination with coating cracks.

  13. Process for preparing multilayer enzyme coating on a fiber

    DOEpatents

    Kim, Jungbae; Kwak, Ja Hun; Grate, Jay W.

    2009-11-03

    A process for preparing high stability, high activity biocatalytic materials is disclosed and processes for using the same. The process involves coating of a material or fiber with enzymes and enzyme aggregate providing a material or fiber with high biocatalytic activity and stability useful in heterogeneous environments. In one illustrative approach, enzyme "seeds" are covalently attached to polymer nanofibers followed by treatment with a reagent that crosslinks additional enzyme molecules to the seed enzymes forming enzyme aggregates thereby improving biocatalytic activity due to increased enzyme loading and enzyme stability. This approach creates a useful new biocatalytic immobilized enzyme system with potential applications in bioconversion, bioremediation, biosensors, and biofuel cells.

  14. Photocatalytic activity of titania coatings synthesised by a combined laser/sol–gel technique

    SciTech Connect

    Adraider, Y.; Pang, Y.X.; Nabhani, F.; Hodgson, S.N.; Sharp, M.C.; Al-Waidh, A.

    2014-06-01

    Highlights: • Sol–gel method was used to prepare titania coatings. • Titania thin films were coated on substrate surface by dip coating. • Fibre laser was employed to irradiate the titania coated surfaces. • Photocatalytic efficiency of titania coatings was significantly improved after laser processing. - Abstract: Titania coatings were prepared using sol–gel method and then applied on the substrate surface by dip coating. Fibre laser (λ = 1064 nm) in continuous wave mode was used to irradiate the titania coated surfaces at different specific energies. The ATR-FTIR, XRD, SEM, EDS and contact angle measurement were employed to analyse surface morphology, phase composition and crystalline structure of laser-irradiated titania coatings, whilst the photocatalytic activity was evaluated by measuring the decomposition of methylene blue (MB) after exposure to the visible light for various illumination times. Results showed that the laser-irradiated titania coatings demonstrate significant different composition and microstructure in comparison with the as-coated from the same sol–gel titania. Photocatalytic efficiency of titania coatings was significantly improved after laser processing. The photocatalytic activity of laser-irradiated titania coatings was higher than that of the as-coated titania. The titania coating processed at laser specific energy of 6.5 J/mm{sup 2} exhibited the highest photocatalytic activity among all titania samples.

  15. Advances in the electrospark deposition coating process

    SciTech Connect

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

    1986-11-01

    Electrospark deposition (ESD) is a pulsed-arc microwelding process using short-duration, high-current electrical pulses to deposit an electrode material on a metallic substrate. It is one of the few methods available by which a fused, metallurgically bonded coating can be applied with such a low total heat input that the bulk substrate material remains at or near ambient temperatures. The short duration of the electrical pulse allows an extremely rapid solidification of the deposited material and results in an exceptionally fine-grained, homogeneous coating that approaches (and with some materials, actually is) an amorphous structure. This structure is believed to contribute to the good tribological and corrosion performance observed for hardsurfacing materials used in the demanding environments of high temperatures, liquid metals, and neutron irradiation. A brief historical review of the process is provided, followed by descriptions of the present state of the art and of the performance and applications of electrospark deposition coating in liquid--metal-cooled nuclear reactors.

  16. Evaluation of Chemical Coating Processes for AXAF

    NASA Technical Reports Server (NTRS)

    Engelhaupt, Darell E.

    1997-01-01

    The need existed at MSFC for the development and fabrication of radioisotope calibration sources of cadmium 109 and iron 55 isotopes. This was in urgent response to the AXAF program. Several issues persisted in creating manufacturing difficulties for the supplier. In order to meet the MSFC requirements very stringent control needed to be maintained for the coating quality, specific activity and thickness. Due to the difficulties in providing the precisely controlled devices for testing, the delivery of the sources was seriously delayed. It became imperative that these fabrication issues be resolved to avoid further delays in this AXAF observatory key component.

  17. Active coatings for SiC particles to reduce the degradation by liquid aluminium during processing of aluminium matrix composites: study of interfacial reactions.

    PubMed

    Ureña, A.; Rodrigo, P.; Baldonedo, J. L.; Gil, L.

    2001-02-01

    The application of a surface coating on SiC particles is studied as an alternative means of solving problems of reactivity between SiC reinforcements and molten aluminium and problems of low wetting which limit the application of casting routes for fabrication of Al-SiCp composites. The selected active barrier was a ceramic composed of SiO2, which was generated by controlled oxidation of the SiC particles. The coating behaves as an active barrier, preventing a direct reaction between molten aluminium and SiC to form Al4C3 as the main degradation product. At the same time, the SiO2 provokes other interfacial reactions, which are responsible for an improvement in wetting behaviour. Composites were prepared by mixing and compacting SiC particles with Al powders followed by melting in a vacuum furnace, and varying the residence time. Transmission electron microscopy (TEM), high resolution electron microscopy (HREM) and field emission TEM were employed as the main characterization techniques to study the interfacial reactions occurring between the barrier and the molten aluminium. These studies showed that the SiO2 coating behaves as an active barrier which reacts with the molten Al to form a glassy phase Al-Si-O. This compound underwent partial crystallization during the composite manufacture to form mullite. The formation of an outer crystalline layer, composed mainly of Al2O3, was also detected. Participation of other secondary interface reactions inside the active barrier was also identified by HREM techniques.

  18. A novel electrostatic dry powder coating process for pharmaceutical dosage forms: immediate release coatings for tablets.

    PubMed

    Qiao, Mingxi; Zhang, Liqiang; Ma, Yingliang; Zhu, Jesse; Chow, Kwok

    2010-10-01

    An electrostatic dry powder coating process for pharmaceutical solid dosage forms was developed for the first time by electrostatic dry powder coating in a pan coater system. Two immediate release coating compositions with Opadry® AMB and Eudragit® EPO were successfully applied using this process. A liquid plasticizer was sprayed onto the surface of the tablet cores to increase the conductivity of tablet cores to enhance particle deposition, electrical resistivity reduced from greater than 1×10(13)Ωm to less than 1×10(9)Ωm, and to lower the glass transition temperature (T(g)) of the coating polymer for film forming in the pan coater. The application of liquid plasticizer was followed by spraying charged coating particles using an electrostatic charging gun to enhance the uniform deposition on tablet surface. The coating particles were coalesced into a thin film by curing at an acceptable processing temperature as formation was confirmed by SEM micrographs. The results also show that the optimized dry powder coating process produces tablets with smooth surface, good coating uniformity and release profile that are comparable to that of the tablet cores. The data also suggest that this novel electrostatic dry powder coating technique is an alternative to aqueous- or solvent-based coating process for pharmaceutical products.

  19. Effect of Porosity on Photocatalytic Activity of Plasma-Sprayed TiO2 Coating

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng; Chaudhary, Ujwal; Das, Santanu; Godavarty, Anuradha; Agarwal, Arvind

    2013-10-01

    The effect of porosity on photocatalytic activity of plasma-sprayed TiO2 coating on steel substrate is studied by varying processing parameters viz. plasma power and powder feed rate. The relationship between porosity content and methylene blue (MB) dye decomposition rate was established to correlate coating microstructure and its photocatalytic activity. The coating with the highest porosity content exhibited best photocatalytic efficiency. The same processing parameters were used to deposit TiO2 coating on FTO glass. The photocatalytic activity of TiO2 coating on FTO was 2.5 times better than TiO2 coating on the steel substrate. TiO2 coating on FTO glass contains bimodal porosity distribution (micropores and submicron pores) which accelerated MB decomposition by accelerated diffusion of ionic species.

  20. Development and application of a process window for achieving high-quality coating in a fluidized bed coating process.

    PubMed

    Laksmana, F L; Hartman Kok, P J A; Vromans, H; Frijlink, H W; Van der Voort Maarschalk, K

    2009-01-01

    Next to the coating formulation, process conditions play important roles in determining coating quality. This study aims to develop an operational window that separates layering from agglomeration regimes and, furthermore, the one that leads to the best coating quality in a fluidized bed coater. The bed relative humidity and the droplet size of the coating aerosol were predicted using a set of engineering models. The coating quality was characterized using a quantitative image analysis method, which measures the coating thickness distribution, the total porosity, and the pore size in the coating. The layering regime can be achieved by performing the coating process at a certain excess of the viscous Stokes number (DeltaSt(v)). This excess is dependent on the given bed relative humidity and droplet size. The higher the bed relative humidity, the higher is the DeltaSt(v) required to keep the process in the layering regime. Further, it is shown that using bed relative humidity and droplet size alone is not enough to obtain constant coating quality. The changes in bed relative humidity and droplet size have been identified to correlate to the fractional area of particles sprayed per unit of time. This parameter can effectively serve as an additional parameter to be considered for a better control on the coating quality. High coating quality is shown to be achieved by performing the process close to saturation and spraying droplets small enough to obtain high spraying rate, but not too small to cause incomplete coverage of the core particles.

  1. Applications of edible films and coatings to processed foods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Edible coatings have been successfully applied in processed foods such as meat, cereals, confectionaries, dried fruits, nuts and fresh and fresh-cut fruits and vegetables. These coatings are used to improve the quality and shelf-life of foods. Furthermore, different food ingredients, derived from ...

  2. Iron-Based Amorphous Coatings Produced by HVOF Thermal Spray Processing-Coating Structure and Properties

    SciTech Connect

    Beardsley, M B

    2008-03-26

    The feasibility to coat large SNF/HLW containers with a structurally amorphous material (SAM) was demonstrated on sub-scale models fabricated from Type 316L stainless steel. The sub-scale model were coated with SAM 1651 material using kerosene high velocity oxygen fuel (HVOF) torch to thicknesses ranging from 1 mm to 2 mm. The process parameters such as standoff distance, oxygen flow, and kerosene flow, were optimized in order to improve the corrosion properties of the coatings. Testing in an electrochemical cell and long-term exposure to a salt spray environment were used to guide the selection of process parameters.

  3. Coatings for minimally processed fruits and vegetables

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fresh-cut fruit and vegetables are gaining increasing popularity and market share. Techniques to enhance stability of fresh cut produce are reviewed. Among these techniques, edibles coatings can provide protection against dehydration, microbial decay and decrease events related to physiological sene...

  4. Anodization process produces opaque, reflective coatings on aluminum

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Opaque, reflective coatings are produced on aluminum articles by an anodizing process wherein the anodizing bath contains an aqueous dispersion of finely divided insoluble inorganic compounds. These particles appear as uniformly distributed occlusions in the anodic deposit on the aluminum.

  5. Anti-reflection coatings applied by acid leaching process

    NASA Technical Reports Server (NTRS)

    Pastirik, E.

    1980-01-01

    The Magicote C process developed by S.M. Thompsen was evaluated for use in applying an antireflective coating to the cover plates of solar panels. The process uses a fluosilicic acid solution supersaturated with silica at elevated temperature to selectively attack the surface of soda-lime glass cover plates and alter the physical and chemical composition of a thin layer of glass. The altered glass layer constitutes an antireflective coating. The process produces coatings of excellent optical quality which possess outstanding resistance to soiling and staining. The coatings produced are not resistant to mechanical abrasion and are attacked to some extent by glass cleansers. Control of the filming process was found to be difficult.

  6. Fused slurry silicide coatings for columbium alloy reentry heat shields. Volume 2: Experimental and coating process details

    NASA Technical Reports Server (NTRS)

    Fitzgerald, B.

    1973-01-01

    The experimental and coating process details are presented. The process specifications which were developed for the formulation and application of the R-512E fused slurry silicide coating using either an acrylic or nitrocellulose base slurry system is also discussed.

  7. Plasma process control for improved PEO coatings on magnesium alloys

    NASA Astrophysics Data System (ADS)

    Hussein, Riyad Omran

    Plasma Electrolytic Oxidation (PEO) is a high voltage plasma-assisted oxidation process uses an environmentally-friendly aqueous electrolyte to oxidize the metal surfaces to form ceramic oxide coatings which impart a high corrosion and wear resistance. One of the main advantages of PEO process is that it can be applied to treat samples with complex shapes, and surfaces with different composition and microstructure. The PEO process of Mg alloys is strongly influenced by such parameters as electrolyte composition and concentration, current or voltage applied and substrate alloy. Generally, these parameters have a direct influence on the discharging behavior. The discharges play an essential role in the formation and resulting composition of the 3-layer oxide structure. A detailed knowledge of the coating mechanisms is extremely important in order to produce a desired coating quality to reach the best performance of the PEO coatings in terms of corrosion resistance and tribological properties (wear rate, COF). During PEO processing of magnesium, some of the metal cations are transferred outwards from the substrate and react with anions to form ceramic coatings. Also, due to the high electric field in the discharge channels, oxygen anions transfer towards the magnesium substrate and react with Mg2+ cations to form a ceramic coating. Although, in general, PEO coating of Mg alloys produces the three-layered structure, the relative proportions of the three-layers are strongly influenced by the PEO processing parameters. In PEO process, the ceramic coating grows inwards to the alloy substrate and outwards to the coating surface simultaneously. For the coating growth, there are three simultaneous processes taking place, namely the electrochemical, the plasma chemical reactions and thermal diffusion. Optical emission spectroscopy (OES) was employed for the discharge characterization by following the substrate and electrolyte element present in the plasma discharge during the

  8. Dip Process Thermal Barrier Coating for Superalloys.

    DTIC Science & Technology

    1982-02-02

    the Project Supervisor is Dr. David J. Rowcliffe, Program Manager, Ceramics . Dr. Kai-Hung Lau, Materials Chemist performed the thermogravimetric...ever increasing demand for higher turbine inlet temperature in gas turbines has created an extensive interest in using ceramic materials to protect...airfoil surfaces. During the past decade, a concentrated effort was devoted to developing ceramic thermal barrier coatings to improve turbine

  9. Process for forming a metal compound coating on a substrate

    DOEpatents

    Sharp, D.J.; Vernon, M.E.; Wright, S.A.

    1988-06-29

    A method of coating a substrate with a thin layer of a metal compound by forming a dispersion of an electrophoretically active organic colloid and a precursor of the metal compound in an electrolytic cell in which the substrate is an electrode. Upon application of an electric potential, the electrode is coated with a mixture of the organic colloid and the precursor to the metal compound, and the coated substrate is then heated in the presence of an atmosphere or vacuum to decompose the organic colloid and form a coating of either a combination of metal compound and carbon, or optionally forming a porous metal compound coating by heating to a temperature high enough to chemically react the carbon.

  10. Process for forming a metal compound coating on a substrate

    DOEpatents

    Sharp, Donald J.; Vernon, Milton E.; Wright, Steven A.

    1991-01-01

    A method of coating a substrate with a thin layer of a metal compound by forming a dispersion of an electrophoretically active organic colloid and a precursor of the metal compound in an electrolytic cell in which the substrate is an electrode. Upon application of an electric potential, the electrode is coated with a mixture of the organic colloid and the precursor to the metal compound, and the coated substrate is then heated in the presence of an atmosphere or vacuum to decompose the organic colloid and form a coating of either a combination of metal compound and carbon, or optionally forming a porous metal compound coating by heating to a temperature high enough to chemically react the carbon.

  11. Use of edible coatings to preserve quality of lightly (and slightly) processed products.

    PubMed

    Baldwin, E A; Nisperos-Carriedo, M O; Baker, R A

    1995-11-01

    Lightly processed agricultural products present a special problem to the food industry and to scientists involved in postharvest and food technology research. Light or minimal processing includes cutting, slicing, coring, peeling, trimming, or sectioning of agricultural produce. These products have an active metabolism that can result in deteriorative changes, such as increased respiration and ethylene production. If not controlled, these changes can lead to rapid senescence and general deterioration of the product. In addition, the surface water activity of cut fruits and vegetables is generally quite high, inviting microbial attack, which further reduces product stability. Methods for control of these changes are numerous and can include the use of edible coatings. Also mentioned in this review are coating of nut products, and dried, dehydrated, and freeze-dried fruits. Technically, these are not considered to be minimally processed, but many of the problems and benefits of coating these products are similar to coating lightly processed products. Generally, the potential benefits of edible coatings for processed or lightly processed produce is to stabilize the product and thereby extend product shelf life. More specifically, coatings have the potential to reduce moisture loss, restrict oxygen entrance, lower respiration, retard ethylene production, seal in flavor volatiles, and carry additives that retard discoloration and microbial growth.

  12. Study on Ceramic Interconnect Manufactured by Slurry Dip Coating and Plasma Spray Coating Processes

    NASA Astrophysics Data System (ADS)

    Lee, Gil-Yong; Kim, Jong-Hee; Ryoo, Sung-Nam; Peck, Dong-Hyun; Jung, Doo-Hwan; Shul, Yong-Gun; Shin, Dong-Ryul; Song, Rak-Hyun

    To get a stable and dense interconnect layer of anode-supported flat tubular solid oxide fuel cell stack, we have studied on the synthesis of precursors with a fine particle size and the ceramic interconnect coating technology. Coated interconnects by slurry dipping and air plasma spray processes were sintered by 2-step sintering method. Ca-doped LaCrO3 perovskites such as La0.75Ca0.27CrO3(LCC27), La0.6Ca0.41CrO3(LCC41), and La0.8Sr0.05Ca0.15CrO3(LSCC), were synthesized by Pechini process and their average particle sizes were about 1 μm. LSCC layer is a functional layer to prevent Ca migration and then LCC41 layer is coated onto it. The Ca migration in the LSCC layer did not occur. The LCC41 was coated on the air plasma spray-coated LCC27 layer by slurry dip coating process and sintered at 1200°C for 20hr. Its electrical conductivity indicated about 27 S/cm at 800°C and the bubble test showed that there is no gas permeation at pressure difference of 0.4 kgf/cm2 at room temperature.

  13. A production parylene coating process for hybrid microcircuits

    NASA Technical Reports Server (NTRS)

    Kale, V. S.; Riley, T. J.

    1977-01-01

    The real impetus for developing a production parylene coating process for internal hybrid passivation came as a result of the possibility of loose conductive particles in hybrid microelectronic circuits, causing intermittent and sometimes permanent failures. Because of the excellent mechanical properties of parylene, it is capable of securing the loose particles in place and prevent such failures. The process of coating described consists of (1) vaporizing the initial charge, which is in the form of a dimer; (2) conversion of the dimer into a reactive monomer; and (3) deposition and subsequent polymerization of the monomer in the deposition chamber which forms a uniform parylene film over all the cold surfaces in contact. Experimental results are discussed in terms of wire bond reliability, resistor drift, high-temperature storage characteristics of parylene, and coating acceptance standards. It is concluded that internal cavities of microelectronic circuits can be successfully coated with parylene provided appropriate tooling is used to protect external leads from the parylene monomer.

  14. Polymeric spheres on substrates from a spin-coating process.

    PubMed

    Liu, Ying-Ling; Chen, Shi-Yi; Wang, Ko-Shung

    2009-02-01

    Formation of polymeric spheres in nanometer to sub-micrometer is achieved through a spin-coating process with polyamide (from 4,4(')-(hexafluoroisopropylidene)dianiline and 4,4(')-dicarboxydiphenylether) solutions in N,N-dimethylformamide and N,N-dimethylacetamide. The formation of polymeric spheres and their sizes are dependent on the polymer solution concentrations and the rates in spin-coating. The polymeric spheres could be obtained on various substrates including silicon, mica, and glass.

  15. Morphology-insensitive Performance Facilitates Transition from Spin-Coating to Roll-to-Roll Coating For High-Performance, Solution-Processed Solar Cells

    NASA Astrophysics Data System (ADS)

    Delongchamp, Dean

    Solution processing via roll-to-roll (R2R) coating promises a low cost, low thermal-budget, sustainable revolution for the production of solar cells. Yet virtually all high efficiency solution processed research cells have been demonstrated by spin-coating, a low-volume deposition process. We present detailed device and morphology studies of an organic photovoltaic (OPV) system deposited by a high volume manufacturing technique, blade-coating, that achieves greater than 9.5 % power conversion efficiency (PCE). The average crystal domain orientation and characteristic phase separation length distribution are markedly different when deposited by blade-coating rather than spin-coating,. This result allows us to determine which aspects of morphology are not relevant to the PCE of this system. Whether the crystallites are ``face on'' or ``edge on'' does not appear to impact the PCE of system, nor does the length scale or ``hierarchical'' nature of the phase length scale. Persistent morphological qualities that may be associated with high PCE in this system are relatively pure phases and relatively strong diffraction. We posit that OPV systems in which the PCE is less sensitive to morphology may also be less sensitive to film thickness, enabling some to maintain high PCE in active layers thicker than greater than ~200 nm. We confirm that blade-coating is a suitable prototyping technique for R2R coating by demonstrating nominally identical morphologies for both piece blade-coating and continuous-web, slot-die coating.

  16. Antimicrobial activity of antiseptic-coated orthopaedic devices.

    PubMed

    Darouiche, R O; Green, G; Mansouri, M D

    1998-04-01

    Antimicrobial coating of medical devices, including fracture fixation devices, has evolved as a potentially effective method for preventing device-related infections. We examined the in vitro antimicrobial activity of titanium cylinders coated with the antiseptic combination of chlorhexidine and chloroxylenol. The coated devices provided zones of inhibition against Staphylococcus epidermidis, S. aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans, at baseline and up to 8 weeks after incubation of the coated cylinders in human serum at 37 degrees C. This durable antimicrobial activity was attributed to the relatively slow leaching of chlorhexidine and chloroxylenol from the coated cylinders as measured by high-performance liquid chromatography. These results suggest that antiseptic-coated orthopaedic devices may provide broad-spectrum and durable antimicrobial protection against device-related infection.

  17. Sol-gel multilayers applied by a meniscus coating process

    SciTech Connect

    Britten, J.A.; Thomas, I.M.

    1992-03-19

    We describe a meniscus coating method to produce high-laser damage threshold, silica/alumina sol-gel multilayer reflectors on 30 {plus} cm substrates for laser-fusion applications. This process involves forcing a small suspension flow through a porous applicator tube, forming a falling film on the tube. A substrate contacts this film to form a meniscus. Motion of the substrate relative to the applicator entrains a thin film on the substrate, which leaves behind a porous, optical quality film upon solvent evaporation. We develop a solution for the entrained film thickness as a function of geometry, flow and fluid properties by an analysis similar to that of the classical dip-coating problem. This solution is compared with experimental measurements. Also, preliminary results of multilayer coating experiments with a prototype coater are presented, which focus on coating uniformity and laser damage threshold (LDT).

  18. Processing-microstructure-properties relationships in small-particle plasma-sprayed ceramic coatings

    NASA Astrophysics Data System (ADS)

    Mawdsley, Jennifer Renee

    The objective of this study was to determine processing-microstructure-properties relationships for small-particle plasma-sprayed (SPPS) ceramic coatings. Plasma-sprayed yttria partially-stabilized zirconia (YSZ) coatings, which are used to protect superalloys from heat and the environment in turbine engines, and plasma-sprayed alumina coatings, which are being investigated as a potential replacement for chrome in corrosion protection applications, were fabricated using SPPS technology and their microstructure and pertinent properties were examined. The properties of plasma-sprayed YSZ and alumina coatings were investigated with designed experiments. The parameters varied include power, spray distance, total plasma gas flow, percent hydrogen in the plasma gas, injector angle, injector offset and carrier gas flow. The variations in thermal diffusivity, thermal conductivity, elastic modulus, and hardness for the YSZ SPPS coatings were found to correlate to the variations in density, which were related to the processing variables. It was found that surface roughness was related to the amount of splashing and debris associated with the single splats. In four-point bending strain tolerance and fatigue tests, the SPPS YSZ coatings showed very little acoustic emission activity, except in the case of tensile fatigue of a coating without network cracks. Small angle X-ray scattering experiments revealed that SPPS YSZ coatings have significantly less submicron intersplat porosity than conventional plasma-sprayed coatings, and that the pore and microcrack scattering area decreases with heat treatment due to the sintering of microcracks and small pores. The SPPS alumina coatings were optimized to produce a coating with excellent corrosion protection capabilities. It was found that the hardest SPPS alumina coatings did not provide the best corrosion protection due to unique porosity defect structures associated with surface bumps in the coatings. The surface bumps were

  19. A Novel Nonelectrolytic Process for Chromium and Nickel Coating

    DTIC Science & Technology

    2015-06-01

    imperfect and contained impurities. Clearly, metal can be deposited with RES like processes, but further development will be needed to create metal...the desired metals. However, the coating morphology was imperfect and contained impurities. Clearly, metal can be deposited with RES like processes...14 4. Physical Vapor Deposition ................................................................15 E. MILITARY

  20. Scale-up of a pan-coating process.

    PubMed

    Pandey, Preetanshu; Turton, Richard; Joshi, Nitin; Hammerman, Elizabeth; Ergun, James

    2006-01-01

    The purpose of this work was to develop a practical scale-up model for a solvent-based pan-coating process. Practical scale-up rules to determine the key parameters (pan load, pan speed, spray rate, air flow) required to control the process are proposed. The proposed scale-up rules are based on a macroscopic evaluation of the coating process. Implementation of these rules does not require complex experimentation or prediction of model parameters. The proposed scale-up rules were tested by conducting coating scale-up and scale-down experiments on 24-inch and 52-inch Vector Hi-coaters. The data demonstrate that using these rules led to similar cumulative drug release profiles (f2 > 50; and P Analysis of Variance [PANOVA] > 0.05 for cumulative percentage of drug released after 12 hours [Cum12]) from tablets made at 24- and 52-inch scales. Membrane characteristics such as opacity and roughness were also similar across the 2 scales. The effects of the key process variables on coat weight uniformity and membrane characteristics were also studied. Pan speed was found to be the most significant factor related to coating uniformity. Spray droplet size was found to affect the membrane roughness significantly, whereas opacity was affected by the drying capacity.

  1. Martensitic transformations in laser processed coatings

    SciTech Connect

    Burg, M. van den; De Hosson, J.T.M. . Dept. of Applied Physics)

    1993-09-01

    This paper concentrates on laser coating of Fe-22 wt% Cr and a duplex steel SAF2205 by injecting Cr[sub 2]O[sub 3] powder into the melt pool. In particular the work focuses on the stabilization of high temperature distorted spinel phases due to the high quench rates involved as well as on the a quantitative crystallographic analysis of the resulting morphologies. The microstructure observed in TEM indicates that the material does not solidify in the distorted spinel structure. The presence of a small amount of cubic (Fe, Cr)-spinel suggests that the distorted spinel in fact might be nucleated from the cubic spinel phase. The plate like morphology of the distorted spinel phase in combination with the twinned internal structure of the plates put forward the idea that the transformation might be martensitic. Martensitic calculations executed with the lattice parameters of the cubic and distorted (Fe, Cr)-spinel phases are in excellent agreement with the experimental data confirming that the transformation might be martensitic indeed.

  2. Dehydration processes using membranes with hydrophobic coating

    DOEpatents

    Huang, Yu; Baker, Richard W; Aldajani, Tiem; Ly, Jennifer

    2013-07-30

    Processes for removing water from organic compounds, especially polar compounds such as alcohols. The processes include a membrane-based dehydration step, using a membrane that has a dioxole-based polymer selective layer or the like and a hydrophilic selective layer, and can operate even when the stream to be treated has a high water content, such as 10 wt % or more. The processes are particularly useful for dehydrating ethanol.

  3. Process for depositing hard coating in a nozzle orifice

    DOEpatents

    Flynn, Paul L.; Giammarise, Anthony W.

    1991-01-01

    The present invention is directed to a process for coating the interior surfaces of an orifice in a substrate that forms a slurry fuel injection nozzle. In a specific embodiment, the nozzle is part of a fuel injection system for metering a coal-water slurry into a large, medium-speed, multi-cylinder diesel engine. In order to retard erosion of the orifice, the substrate is placed in a chemical vapor deposition (CVD) reaction chamber. A reaction gas is passed into the chamber at a gas temperature below its reaction temperature and is directed through the orifice in the substrate. The gas reaction temperature is a temperature at and above which the reaction gas deposits as a coating, and the reaction gas is of a composition whereby improved resistance toerosion by flow of the particulates in the slurry fuel is imparted by the deposited coating. Only the portion of the substrate in proximity to the orifice to be coated is selectively heated to at least the gas reaction temperature for effecting coating of the orifice's interior surfaces by the vapor deposited coating formed from the reaction gas.

  4. Process for depositing hard coating in a nozzle orifice

    DOEpatents

    Flynn, P.L.; Giammarise, A.W.

    1991-10-29

    The present invention is directed to a process for coating the interior surfaces of an orifice in a substrate that forms a slurry fuel injection nozzle. In a specific embodiment, the nozzle is part of a fuel injection system for metering a coal-water slurry into a large, medium-speed, multi-cylinder diesel engine. In order to retard erosion of the orifice, the substrate is placed in a chemical vapor deposition (CVD) reaction chamber. A reaction gas is passed into the chamber at a gas temperature below its reaction temperature and is directed through the orifice in the substrate. The gas reaction temperature is a temperature at and above which the reaction gas deposits as a coating, and the reaction gas is of a composition whereby improved resistance to erosion by flow of the particulates in the slurry fuel is imparted by the deposited coating. Only the portion of the substrate in proximity to the orifice to be coated is selectively heated to at least the gas reaction temperature for effecting coating of the orifice's interior surfaces by the vapor deposited coating formed from the reaction gas. 2 figures.

  5. Electrocatalytically Active Nickel-Based Electrode Coatings Formed by Atmospheric and Suspension Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Aghasibeig, M.; Mousavi, M.; Ben Ettouill, F.; Moreau, C.; Wuthrich, R.; Dolatabadi, A.

    2014-01-01

    Ni-based electrode coatings with enhanced surface areas, for hydrogen production, were developed using atmospheric plasma spray (APS) and suspension plasma spray (SPS) processes. The results revealed a larger electrochemical active surface area for the coatings produced by SPS compared to those produced by APS process. SEM micrographs showed that the surface microstructure of the sample with the largest surface area was composed of a large number of small cauliflower-like aggregates with an average diameter of 10 μm.

  6. Plasma assisted surface coating/modification processes - An emerging technology

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1987-01-01

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation. These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  7. Plasma assisted surface coating/modification processes: An emerging technology

    NASA Astrophysics Data System (ADS)

    Spalvins, T.

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation). These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  8. Plasma assisted surface coating/modification processes - An emerging technology

    NASA Astrophysics Data System (ADS)

    Spalvins, T.

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation. These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  9. Plasma assisted surface coating/modification processes: An emerging technology

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1986-01-01

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation). These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  10. Processing and evaluation of bioactive coatings on polymeric implants.

    PubMed

    Rabiei, Afsaneh; Sandukas, Stefan

    2013-09-01

    Polyetheretherketone (PEEK) is a high-performance polymer with advantages over metallic biomaterials for application in spinal implants. In this study, hydroxyapatite (HA) coatings were deposited onto PEEK substrates using radio-frequency magnetron sputtering for the purpose of improving bioactivity. An intermediate coating layer of yttria-stabilized zirconia (YSZ) was first deposited onto the PEEK substrates to provide heat shielding during subsequent post-deposition heat treatment to prevent degradation of PEEK substrates and coating/substrate interface. Plasma activation of the PEEK substrate surfaces before deposition resulted in a significant increase in coating adhesion strength. Post-deposition heat treatments of microwave and hydrothermal annealing were studied with the goal of forming crystalline HA without the use of high temperatures required in conventional annealing. Microstructural and compositional analyses by scanning electron microscopy (SEM) and X-ray diffraction revealed that the YSZ layer exhibited a crystalline structure as-deposited, with columnar grains oriented along the growth direction, whereas the HA layer was shown to be amorphous as-deposited. After microwave annealing, the HA coating exhibited a columnar crystalline microstructure, similar to that of the underlying YSZ crystalline layer; XRD analysis confirmed a crystalline HA phase in the coating. It is suggested that the existence of the crystalline YSZ layer aids in the formation of the HA layer upon heating, possibly lowering the activation energy for crystallization by providing nucleation sites for HA grain formation. Cell culture tests showed a significant increase in initial cell attachment and growth on the microwave-annealed coatings, compared with uncoated PEEK and amorphous HA surfaces.

  11. Sustained release coating of tablets with Eudragit(®) RS/RL using a novel electrostatic dry powder coating process.

    PubMed

    Qiao, Mingxi; Luo, Yanfeng; Zhang, Liqiang; Ma, Yingliang; Stephenson, Tyler Shawn; Zhu, Jesse

    2010-10-31

    The objectives of this study were to develop an electrostatic dry powder coating process for sustained coating tablets with Eudragit(®) RS/RL and to investigate the effects of various factors and operating conditions on the coating process and drug release profile. A liquid plasticizer (triethyl citrate) was sprayed onto the surface of the tablets followed by spraying coating powder by an electrostatic spray gun. The powder coated tablets were cured at elevated temperature for a film formation. Liquid plasticizer played important roles in lowering down the glass transition temperature (T(g)) of the coating polymer and increasing the surface electrical conduction of tablet cores. Electrostatic assisted coating deposition was confirmed by the fact that higher coating level was obtained with electrical charging than the ones without it. The micrographs of scanning electron microscopy (SEM) of coated tablets showed that the film formation mainly occurred during the curing step. Higher curing temperature and longer curing time help enhance the film formation. The in vitro drug release profiles indicated that curing time, temperature, coating level and ratio of Eudragit(®) RS/RL were the main factors affecting the sustained release profile. The electrostatic dry powder coating process has been demonstrated to be an alternative for tablet sustained release coating with Eudragit(®) RS and RL.

  12. Potentiodynamic study of Al-Mg alloy with superhydrophobic coating in photobiologically active/not active natural seawater.

    PubMed

    Benedetti, Alessandro; Cirisano, Francesca; Delucchi, Marina; Faimali, Marco; Ferrari, Michele

    2016-01-01

    Superhydrophobic coating technology is regarded as an attractive possibility for the protection of materials in a sea environment. DC techniques are a useful tool to characterize metals' behavior in seawater in the presence/absence of coatings and/or corrosion inhibitors. In this work, investigations concerning Al-5%Mg alloy with and without a sprayed superhydrophobic coating were carried out with potentiodynamic scans in photobiologically active and not active seawater (3 weeks of immersion). In not photobiologically active seawater, the presence of the superhydrophobic coating did not prevent pitting corrosion. With time, the coating underwent local exfoliations, but intact areas still preserved superhydrophobicity. In photobiologically active seawater, on samples without the superhydrophobic coating (controls) pitting was inhibited, probably due to the adsorption of organic compounds produced by the photobiological activity. After 3 weeks of immersion, the surface of the coating became hydrophilic due to diatom coverage. As suggested by intermediate observations, the surface below the diatom layer is suspected of having lost its superhydrophobicity due to early stages of biofouling processes (organic molecule adsorption and diatom attachment/gliding). Polarization curves also revealed that the metal below the coating underwent corrosion inhibiting phenomena as observed in controls, likely due to the permeation of organic molecules through the coating. Hence, the initial biofouling stages (days) occurring in photobiologically active seawater can both accelerate the loss of superhydrophobicity of coatings and promote corrosion inhibition on the underlying metal. Finally, time durability of superhydrophobic surfaces in real seawater still remains the main challenge for applications, where the early stages of immersion are demonstrated to be of crucial importance.

  13. PROCESS OF COATING GRAPHITE WITH NIOBIUM-TITANIUM CARBIDE

    DOEpatents

    Halden, F.A.; Smiley, W.D.; Hruz, F.M.

    1961-07-01

    A process of coating graphite with niobium - titanium carbide is described. It is found that the addition of more than ten percent by weight of titanium to niobium results in much greater wetting of the graphite by the niobium and a much more adherent coating. The preferred embodiment comprises contacting the graphite with a powdered alloy or mixture, degassing simultaneously the powder and the graphite, and then heating them to a high temperature to cause melting, wetting, spreading, and carburization of the niobium-titanium powder.

  14. New ceramic coating technique using laser spraying process

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Koichi; Yanagisawa, Takeshi; Uchiyama, Futodhi; Obara, Akira; Okutomi, Mamoru; Kimura, Shinji; Yamada, Akimasa; Shen, Hong L.; Wang, Zhongcheng; Shen, Qinwo; Chatterjee, Udit; Bhar, Gopal C.

    1998-08-01

    A new ceramic coating technique using a CO2 laser has been developed. A high power density laser beam passes near the substrate. Coating materials are supplied by an extra-high accuracy powder supply device and pass across the laser beam. The coating materials are melted in the laser beam and deposited on the substrate surface. A YSZ (Yttria Stabilized Zirconia) layer and a LaCoO3 layer are made for high temperature solid oxide fuel cells. The crystal structures of the coated layers are the same as that of the original coating materials. Superconducting BPSCCO ceramic films are also made with this process. The films show super-conductivity with Tc at 81 K. The Jc of the specimen is 440 A/cm2 at 77 K. We can easily handle and arrange not only metal but also refractory materials. By adopting a multi-axis robot and a surface treatment laser technique, the laser spraying method described here makes it possible to produce highly functional and three dimensional parts of devices directly from raw powder materials. Thus the proposed method will open the path to an unexplored field of key production technology.

  15. Effect of calcinations temperature on microstructures, photocatalytic activity and self-cleaning property of TiO2 and SnO2/TiO2 thin films prepared by sol-gel dip coating process

    NASA Astrophysics Data System (ADS)

    Sangchay, Weerachai

    2014-06-01

    The purpose of this research was to study the effect of calcinations temperature on phase transformation, crystallite size, morphology, photocatalytic activity and self-cleaning properties of TiO2 and SnO2/TiO2 thin films. The thin films were preparation by sol-gel dip coating process and calcinations at the temperature of 500 °C, 600 °C and 700 °C for 2 h with the heating rate of 10 °C/mim. The microstructures of the fabricated thin films were characterized by XRD and SEM techniques. The photocatalytic activity of the thin films was also tested via the degradation of methylene blue solution under UV irradiation. Finally, self-cleaning properties of thin films were evaluated by measuring the contact angle of water droplet on the thin films with and without UV irradiation. It was found that SnO2/TiO2 thin films calcinations at the temperature of 500 °C shows the highest of photocatalytic activity and self-cleaning properties.

  16. Superhydrophobic activated carbon-coated sponges for separation and absorption.

    PubMed

    Sun, Hanxue; Li, An; Zhu, Zhaoqi; Liang, Weidong; Zhao, Xinhong; La, Peiqing; Deng, Weiqiao

    2013-06-01

    Highly porous activated carbon with a large surface area and pore volume was synthesized by KOH activation using commercially available activated carbon as a precursor. By modification with polydimethylsiloxane (PDMS), highly porous activated carbon showed superhydrophobicity with a water contact angle of 163.6°. The changes in wettability of PDMS- treated highly porous activated carbon were attributed to the deposition of a low-surface-energy silicon coating onto activated carbon (confirmed by X-ray photoelectron spectroscopy), which had microporous characteristics (confirmed by XRD, SEM, and TEM analyses). Using an easy dip-coating method, superhydrophobic activated carbon-coated sponges were also fabricated; those exhibited excellent absorption selectivity for the removal of a wide range of organics and oils from water, and also recyclability, thus showing great potential as efficient absorbents for the large-scale removal of organic contaminants or oil spills from water.

  17. Processing and optimization of functional ceramic coatings and inorganic nanomaterials

    NASA Astrophysics Data System (ADS)

    Nyutu, Edward Kennedy G.

    Processing of functional inorganic materials including zero (0-D) dimensional (e.g. nanoparticles), 1-D (nanorods, nanofibers), and 2-D (films/coating) structures is of fundamental and technological interest. This research will have two major sections. The first part of section one focuses on the deposition of silicon dioxide onto a pre-deposited molybdenum disilicide coating on molybdenum substrates for both high (>1000 °C) and moderate (500-600 °C) temperature oxidation protection. Chemical vapor deposition (CVD/MOCVD) techniques will be utilized to deposit the metal suicide and oxide coatings. The focus of this study will be to establish optimum deposition conditions and evaluate the metal oxide coating as oxidation - thermal barriers for Mo substrates under both isothermal (static) and cyclic oxidation conditions. The second part of this section will involve a systematic evaluation of a boron nitride (BN) interface coating prepared by chemical vapor deposition. Ceramic matrix composites (CMCs) are prospective candidates for high (>1000 °C) temperature applications and fiber- matrix interfaces are the dominant design parameters in ceramic matrix composites (CMCs). An important goal of the study is to determine a set of process parameters, which would define a boron nitride (BN) interface coating by a chemical vapor deposition (CVD) process with respect to coating. In the first part of the second section, we will investigate a new approach to synthesize ultrafine metal oxides that combines microwave heating and an in-situ ultrasonic mixing of two or more liquid precursors with a tubular flow reactor. Different metal oxides such as nickel ferrite and zinc aluminate spinels will be studied. The synthesis of metal oxides were investigated in order to study the effects of the nozzle and microwave (INM process) on the purity, composition, and particle size of the resulting powders. The second part of this research section involves a study of microwave frequency

  18. Acylase-containing polyurethane coatings with anti-biofilm activity.

    PubMed

    Grover, Navdeep; Plaks, Joseph G; Summers, Samantha R; Chado, Garrett R; Schurr, Michael J; Kaar, Joel L

    2016-12-01

    Due to the prevalence of biofilm-related infections, which are mediated by bacterial quorum sensing, there is a critical need for materials and coatings that resist biofilm formation. We have developed novel anti-biofilm coatings that disrupt quorum sensing in surface-associated bacteria via the immobilization of acylase in polyurethane films. Specifically, acylase from Aspergillus melleus was covalently immobilized in biomedical grade polyurethane coatings via multipoint covalent immobilization. Coatings containing acylase were enzymatically active and catalyzed the hydrolysis of the quorum sensing (QS) molecules N-butyryl-L-homoserine lactone (C4-LHL), N-hexanoyl-L-homoserine lactone (C6-LHL), and N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12-LHL). In biofilm inhibition assays, immobilization of acylase led to an approximately 60% reduction in biofilm formation by Pseudomonas aeruginosa ATCC 10145 and PAO1. Inhibition of biofilm formation was consistent with a reduction in the secretion of pyocyanin, indicating the disruption of quorum sensing as the mechanism of the coating activity. Scanning electron microscopy further showed that acylase-containing coatings contained far fewer bacterial cells than control coatings that lacked acylase. Moreover, acylase-containing coatings retained 90% activity when stored dry at 37°C for 7 days and were more stable than the free enzyme in physiological conditions, including artificial urine. Ultimately, such coatings hold considerable promise for the clinical management of catheter-related infections as well as the prevention of infections in orthopedic applications (i.e., on hip and knee prostheses) and on contact lenses. Biotechnol. Bioeng. 2016;113: 2535-2543. © 2016 Wiley Periodicals, Inc.

  19. Turbine repair process, repaired coating, and repaired turbine component

    DOEpatents

    Das, Rupak; Delvaux, John McConnell; Garcia-Crespo, Andres Jose

    2015-11-03

    A turbine repair process, a repaired coating, and a repaired turbine component are disclosed. The turbine repair process includes providing a turbine component having a higher-pressure region and a lower-pressure region, introducing particles into the higher-pressure region, and at least partially repairing an opening between the higher-pressure region and the lower-pressure region with at least one of the particles to form a repaired turbine component. The repaired coating includes a silicon material, a ceramic matrix composite material, and a repaired region having the silicon material deposited on and surrounded by the ceramic matrix composite material. The repaired turbine component a ceramic matrix composite layer and a repaired region having silicon material deposited on and surrounded by the ceramic matrix composite material.

  20. Process for coating an object with silicon carbide

    NASA Technical Reports Server (NTRS)

    Levin, Harry (Inventor)

    1989-01-01

    A process for coating a carbon or graphite object with silicon carbide by contacting it with silicon liquid and vapor over various lengths of contact time. In the process, a stream of silicon-containing precursor material in gaseous phase below the decomposition temperature of said gas and a co-reactant, carrier or diluent gas such as hydrogen is passed through a hole within a high emissivity, thin, insulating septum into a reaction chamber above the melting point of silicon. The thin septum has one face below the decomposition temperature of the gas and an opposite face exposed to the reaction chamber. The precursor gas is decomposed directly to silicon in the reaction chamber. A stream of any decomposition gas and any unreacted precursor gas from said reaction chamber is removed. The object within the reaction chamber is then contacted with silicon, and recovered after it has been coated with silicon carbide.

  1. 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.

  2. A novel electrostatic dry coating process for enteric coating of tablets with Eudragit® L 100-55.

    PubMed

    Qiao, Mingxi; Zhang, Liqiang; Ma, Yingliang; Zhu, Jesse; Xiao, Wei

    2013-02-01

    An electrostatic dry coating process based on a liquid pan coater was developed for enteric coating of tablets with Eudragit® L 100-55. Two different liquid plasticizers of triethyl citrate (TEC) and PEG400 were used in the coating process. In contrast to TEC, PEG400 produced good powder adhesion and successful coating. DSC results showed that PEG400 lowered the glass transition temperature (Tg) of Eudragit® L 100-55 to a greater extent than TEC at the same blend ratio, indicating that PEG400 was more effective in plasticizing the polymer. PEG400 showed higher contact angle on both surfaces of tablet cores and coating powders as well as lower absorption into the tablet cores than TEC, suggesting that more PEG400 existed at the interface between tablet core and coating powders. The combination effects of higher plasticizing efficiency and more PEG400 available at the tablet surface produced higher plasticization of Eudragit® L 100-55, leading to the successfully initial powder adhesion. The powder adhesion was further enhanced by the electrostatically assisted coating process, as confirmed by the higher coating level and coating efficiency with electrical charging (60 kV) than the ones without it (0 kV). The micrographs of scanning electron microscopy and in vitro drug release tests of the coated tablets showed that higher curing temperature and longer curing time led to enhanced film formation and acid resistance. The electrostatic dry coating process has been demonstrated to be a promising process for enteric coating of tablets.

  3. Fabrication of flexible ultraviolet photodetectors using an all-spray-coating process

    NASA Astrophysics Data System (ADS)

    Han, Junebeom; Lee, Jonghun; Ju, Sanghyun

    2016-04-01

    We report on a flexible ultraviolet (UV) photodetector fabricated using an all-spray-coating process. Two spray coating units were utilized to deposit semiconducting tin oxide nanowires as an active channel layer and metallic silver nanowires as an electrode layer. The device was mounted on the back of a human hand, and the UV intensities in sunlight were monitored over time. The fabricated flexible UV photodetector showed highly sensitive, stable, and reproducible detection properties. The main advantage of the proposed fabrication method is the extension of the integration environment by allowing direct application on various substrates, such as clothes and human skin, with varying device size and shape.

  4. Coated graphite articles useful in metallurgical processes and method for making same

    DOEpatents

    Holcombe, Cressie E.; Bird, Eugene L.

    1995-01-01

    Graphite articles including crucibles and molds used in metallurgical processes involving the melting and the handling of molten metals and alloys that are reactive with carbon when in a molten state and at process temperatures up to about 2000.degree. C. are provided with a multiple-layer coating for inhibiting carbon diffusion from the graphite into the molten metal or alloys. The coating is provided by a first coating increment of a carbide-forming metal on selected surfaces of the graphite, a second coating increment of a carbide forming metal and a refractory metal oxide, and a third coating increment of a refractory metal oxide. The second coating increment provides thermal shock absorbing characteristics to prevent delamination of the coating during temperature cycling. A wash coat of unstabilized zirconia or titanium nitride can be applied onto the third coating increment to facilitate release of melts from the coating.

  5. Spray-coating process in preparing PTFE-PPS composite super-hydrophobic coating

    NASA Astrophysics Data System (ADS)

    Weng, Rui; Zhang, Haifeng; Liu, Xiaowei

    2014-03-01

    In order to improve the performance of a liquid-floated rotor micro-gyroscope, the resistance of the moving interface between the rotor and the floating liquid must be reduced. Hydrophobic treatment can reduce the frictional resistance between such interfaces, therefore we proposed a method to prepare a poly-tetrafluoroethylene (PTFE)-poly-phenylene sulphide (PPS) composite super-hydrophobic coating, based on a spraying process. This method can quickly prepare a continuous, uniform PTFE-PPS composite super-hydrophobic surface on a 2J85 material. This method can be divided into three steps, namely: pre-treatment; chemical etching; and spraying. The total time for this is around three hours. When the PTFE concentration is 4%, the average contact angle of the hydrophobic coating surface is 158°. If silicon dioxide nanoparticles are added, this can further improve the adhesion and mechanical strength of the super-hydrophobic composite coating. The maximum average contact angle can reach as high as 164° when the mass fraction of PTFE, PPS and silicon dioxide is 1:1:1.

  6. Antimicrobial edible films and coatings for fresh and minimally processed fruits and vegetables: a review.

    PubMed

    Valencia-Chamorro, Silvia A; Palou, Lluís; Del Río, Miguel A; Pérez-Gago, María B

    2011-01-01

    The use of edible films and coatings is an environmentally friendly technology that offers substantial advantages for shelf-life increase of many food products including fruits and vegetables. The development of new natural edible films and coatings with the addition of antimicrobial compounds to preserve fresh and minimally processed fruits and vegetables is a technological challenge for the industry and a very active research field worldwide. Antimicrobial agents have been successfully added to edible composite films and coatings based on polysaccharides or proteins such as starch, cellulose derivatives, chitosan, alginate, fruit puree, whey protein isolated, soy protein, egg albumen, wheat gluten, or sodium caseinate. This paper reviews the development of edible films and coatings with antimicrobial activity, typically through the incorporation of antimicrobial food additives as ingredients, the effect of these edible films on the control of target microorganisms, the influence of antimicrobial agents on mechanical and barrier properties of stand-alone edible films, and the effect of the application of antimicrobial edible coatings on the quality of fresh and fresh-cut fruits and vegetables.

  7. Process optimization of a novel immediate release film coating system using QbD principles.

    PubMed

    Teckoe, Jason; Mascaro, Tracey; Farrell, Thomas P; Rajabi-Siahboomi, Ali R

    2013-06-01

    This work describes a quality-by-design (QbD) approach to determine the optimal coating process conditions and robust process operating space for an immediate release aqueous film coating system (Opadry® 200). Critical quality attributes (CQAs) or associated performance indicators of the coated tablets were measured while coating process parameters such as percent solids of the coating dispersion, coating spray rate, inlet air temperature, airflow rate and pan speed were varied, using a design of experiment protocol. The optimized process parameters were then confirmed by independent coating trials. Disintegration time of coated tablets was not affected by the coating process conditions used in this study, while tablet appearance, as determined by measurement of tablet color, coating defects and gloss was determined to be a CQA. Tablet gloss increased when low spray rate and low percent solids were used, as well as with increased coating pan speed. The study used QbD principles and experimental design models to provide a basis to identify ranges of coating process conditions which afford acceptable product quality. High productivity, color uniformity, and very low defect levels were obtained with Opadry 200 even when using a broad range of coating process conditions.

  8. Role of zinc coating at liquid-vapor interface during laser material processing of zinc coated steel

    NASA Astrophysics Data System (ADS)

    Hwan Lee, Seung; Mazumder, Jyoti

    2013-07-01

    In laser material processing, one of the major interests is characterizing interfacial phenomena induced by thermal phase changes of materials. The interfacial characteristics in the laser processing of multi-coated materials show different behaviors compared to those of single material processing. The difference in thermo-physical properties of the coated and primary materials induces the contrasting characteristics of multiple interfacial phenomena including temperature, recoil pressure, capillary force, and thermo capillary force. The influence of coating layer to the interfacial physics evolutions is difficult to be modeled mathematically when the laser beam penetrates the multi-coated material layer by layer. This paper addresses the role of the zinc coating at the liquid-vapor interface during the laser processing of zinc coated steel, as a representative case of multi-coated materials. Computational modules incorporating the zinc layers were established and selectively applied at the locations where the zinc coatings exist to investigate the interfacial phenomena. The level set method was integrated with the modules to track the evolution of the liquid-vapor interface in a self-consistent manner. The interfacial phenomena characteristics were estimated by a 3D mathematical simulation study. A reflective topography method was employed to validate the mathematical model and to supplement our understandings of the interfacial evolution.

  9. Dodecylamine-loaded halloysite nanocontainers for active anticorrosion coatings

    NASA Astrophysics Data System (ADS)

    Falcón, Jesus; Sawczen, Tiago; Aoki, Idalina

    2015-11-01

    Currently the most promising approach in the corrosion protection by smart coatings is the use of nanoreservoirs loaded with corrosion inhibitors. Nanocontainers are filled with anti-corrosive agents and embedded into a primer coating. Future prospective containers are halloysite nanotubes due to their low price, availability, durability, with high mechanical strength and biocompatibility. The aim of this work is to study the use of halloysite nanotubes as nanocontainers for encapsulated dodecylamine for active corrosion protection of carbon steel. Halloysite clay was characterized by XRD and TGA- thermogravimetric analysis techniques. Halloysite nanotubes were loaded with dodecylamine and embedded into an alkyd primer with a weight ratio of 10 wt.% . The anticorrosive performance of the alkyd primer doped with 10 wt.% of entrapped-dodecylamine halloysite was tested on coated carbon steel by direct exposure of the coated samples with a provoked defect into 0.01 mol/L NaCl corrosive media using electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). EIS and SVET measurements showed the self-healing properties of the doped alkyd coating. Coated samples were also evaluated in a salt spray chamber and the self-healing effect was unequivocally noticed.

  10. Engineering functionality gradients by dip coating process in acceleration mode.

    PubMed

    Faustini, Marco; Ceratti, Davide R; Louis, Benjamin; Boudot, Mickael; Albouy, Pierre-Antoine; Boissière, Cédric; Grosso, David

    2014-10-08

    In this work, unique functional devices exhibiting controlled gradients of properties are fabricated by dip-coating process in acceleration mode. Through this new approach, thin films with "on-demand" thickness graded profiles at the submillimeter scale are prepared in an easy and versatile way, compatible for large-scale production. The technique is adapted to several relevant materials, including sol-gel dense and mesoporous metal oxides, block copolymers, metal-organic framework colloids, and commercial photoresists. In the first part of the Article, an investigation on the effect of the dip coating speed variation on the thickness profiles is reported together with the critical roles played by the evaporation rate and by the viscosity on the fluid draining-induced film formation. In the second part, dip-coating in acceleration mode is used to induce controlled variation of functionalities by playing on structural, chemical, or dimensional variations in nano- and microsystems. In order to demonstrate the full potentiality and versatility of the technique, original graded functional devices are made including optical interferometry mirrors with bidirectional gradients, one-dimensional photonic crystals with a stop-band gradient, graded microfluidic channels, and wetting gradient to induce droplet motion.

  11. Hot isostatic pressing-processed hydroxyapatite-coated titanium implants: light microscopic and scanning electron microscopy investigations.

    PubMed

    Wie, H; Herø, H; Solheim, T

    1998-01-01

    Hot isostatic pressing (HIP) was used in a new procedure to produce hydroxyapatite (HA) coatings on a commercially pure titanium (cpTi) substrate for osseous implantation. Eighteen HIP-processed HA-coated implants were placed in the inferior border of the mandibles in 2 Labrador retriever dogs and left submerged for 3 months. As control specimens, 12 sandblasted cpTi implants were placed in the same mandibles and, to compare the bone reaction, 2 additional plasma-sprayed HA-coated implants (Integral) were placed. Tissue reactions at the bony interfaces of the implants were studied in ground sections with the implants in situ, using ordinary, fluorescent, and polarized light microscopy and scanning electron microscopy (SEM). The HIP-processed HA coatings displayed an increased density in light microscopy and SEM as compared to plasma-sprayed coatings. Direct bone-implant contact was found in all 3 types of surfaces. However, the production of new bone was far more abundant for the HA-coated implants than for sandblasted cpTi implants. The presence of bone-forming and bone-resorbing cells indicated active bone remodeling in the interface area at 3 months after implant placement. The present results support the view that epitaxial bone growth may occur from the HA-coated implant surface. It was concluded that the increased density of the present HIP-processed HA material does not reduce the bioactive properties of the coatings.

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

    SciTech Connect

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

    2008-07-01

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

  13. Processing and Development of Nano-Scale HA Coatings for Biomedical Application

    DTIC Science & Technology

    2005-01-01

    thickness of the film has been processed and tested as a more effective orthopedic/ dental implant coating. The present study aims to increase the service...life of an orthopedic/ dental implant by creating materials that form a strong, long lasting, bond with the Ti substrate as well as juxtaposed bone... dental replacement surgery may quickly return to a normal active lifestyle. Cross-sectional transmission electron microscopy analysis displayed that the

  14. Structurally Integrated, Damage Tolerant Thermal Spray Coatings: Processing Effects on Surface and System Functionalities

    NASA Astrophysics Data System (ADS)

    Vackel, Andrew

    Thermal Spray (TS) coatings have seen extensive application as protective surfaces to enhance the service life of substrates prone to damage in their operating environment (wear, corrosion, heat etc.). With the advent of high velocity TS processes, the ability to deposit highly dense (>99%) metallic and cermet coatings has further enhanced the protective ability of these coatings. In addition to surface functionality, the influence of the coating application on the mechanical performance of a coated component is of great concern when such a component will experience either static or cyclic loading during service. Using a process mapping methodology, the processing-property interplay between coating materials meant to provide damage tolerant surface or for structural restoration are explored in terms of relevant mechanical properties. Most importantly, the residual stresses inherent in TS deposited coatings are shown to play a significant role in the integrated mechanical performance of these coatings. Unique to high velocity TS processes is the ability to produce compressive stresses within the deposit from the cold working induced by the high kinetic energy particles upon impact. The extent of these formation stresses are explored with different coating materials, as well as processing influence. The ability of dense TS coatings to carry significant structural load and synergistically strengthen coated tensile specimens is demonstrated as a function of coating material, processing, and thickness. The sharing of load between the substrate and otherwise brittle coating enables higher loads before yield for the bi-material specimens, offering a methodology to improve the tensile performance of coated components for structural repair or multi-functionality (surface and structure). The concern of cyclic fatigue damage in coated components is explored, since the majority of service application are designed for loading to be well below the yield point. The role of

  15. 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)

  16. Active braze process

    SciTech Connect

    Levine, I.L.; Pike, R.A.

    1990-11-02

    Active metal bonding using Cusil (silver-copper) braze alloys is a well established method used at GE Neutron Devices (GEND) for bonding metal to metal, metal to ceramics, and ceramics to ceramics. However, there are many instances in which using a silver alloy for bonding is undesirable (e.g., in vacuum tube envelopes, or where sequential braze steps at different temperatures are required to complete an assembly). The Material and Processes Laboratory at GEND has discovered a new method of active brazing with non-silver alloys which has proved especially successful in ceramic-to-ceramic joints. This method has the added advantage of eliminating several steps which are required in conventional bonding techniques. 2 figs., 10 tabs.

  17. Laser processing of bioactive tricalcium phosphate coating on titanium for load-bearing implants.

    PubMed

    Roy, Mangal; Vamsi Krishna, B; Bandyopadhyay, Amit; Bose, Susmita

    2008-03-01

    Laser-engineered net shaping (LENS), a commercial rapid prototyping (RP) process, was used to coat titanium with tricalcium phosphate (TCP) ceramics to improve bone cell-materials interactions. During LENS coating process, the Nd:YAG laser melts the top surface of Ti substrate in which calcium phosphate powder is fed to create a TCP-Ti composite layer. It was found that an increase in laser power and/or powder feed rate increases the thickness of the coating. However, coating thickness decreased with increasing laser scan speed. TCP coating showed columnar titanium grains at the substrate side of the coating and transitioned to equiaxed titanium grains at the outside. When the scan speed was reduced from 15 to 10mms(-1), coating hardness increased from 882+/-67 to 1049+/-112Hv due to an increase in the volume fraction of TCP in the coating. Coated surfaces showed uniformly distributed TCP particles and X-ray diffraction data confirmed the absence of any undesirable phases, while maintaining a high level of crystallinity. The effect of TCP coating on cell-material interaction was examined by culturing osteoprecursor cells (OPC1) on coated surfaces. The results indicated that TCP coating had good biocompatibility where OPC1 cells attached and proliferated on the coating surface. The coating also initiated cell differentiation, ECM formation and biomineralization.

  18. Antifungal activity in seed coat extracts of woodland plants.

    PubMed

    Warr, Susan J; Thompson, Ken; Kent, Martin

    1992-11-01

    Aqueous extracts from seeds of four woodland ground flora species (Hyacinthoides non-scripta, Allium ursinum, Digitalis purpurea and Hypericum pulchrum) were tested for antifungal activity using a petriplate technique. Four species of fungi were investigated. The growth of three of these (Trichoderma viride, Rhizoctonia solani and Pythium sp.) was not affected by any of the seed coat extracts. The growth of Botrytis cinerea was inhibited by the seed coat extracts of Digitalis purpurea and Hypericum pulchrum but not by those of Hyacinthoides non-scripta or Allium ursinum. The buried seeds of Digitalis purpurea and Hypericum pulchrum can survive in woodland soils for long periods, whereas those of Hyacinthoides non-scripta and Allium ursinum are short-lived. The presence of antifungal agents in the seed coats of persistent species and their possible role in protecting seeds against fungal pathogens is discussed.

  19. Activated carbon coated palygorskite as adsorbent by activation and its adsorption for methylene blue.

    PubMed

    Zhang, Xianlong; Cheng, Liping; Wu, Xueping; Tang, Yingzhao; Wu, Yucheng

    2015-07-01

    An activation process for developing the surface and porous structure of palygorskite/carbon (PG/C) nanocomposite using ZnCl2 as activating agent was investigated. The obtained activated PG/C was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (SEM), and Brunauer-Emmett-Teller analysis (BET) techniques. The effects of activation conditions were examined, including activation temperature and impregnation ratio. With increased temperature and impregnation ratio, the collapse of the palygorskite crystal structure was found to accelerate and the carbon coated on the surface underwent further carbonization. XRD and SEM data confirmed that the palygorskite structure was destroyed and the carbon structure was developed during activation. The presence of the characteristic absorption peaks of CC and C-H vibrations in the FTIR spectra suggested the occurrence of aromatization. The BET surface area improved by more than 11-fold (1201 m2/g for activated PG/C vs. 106 m2/g for PG/C) after activation, and the material appeared to be mainly microporous. The maximum adsorption capacity of methylene blue onto the activated PG/C reached 351 mg/g. The activated PG/C demonstrated better compressive strength than activated carbon without palygorskite clay.

  20. Process for producing a high emittance coating and resulting article

    NASA Technical Reports Server (NTRS)

    Le, Huong G. (Inventor); O'Brien, Dudley L. (Inventor)

    1993-01-01

    Process for anodizing aluminum or its alloys to obtain a surface particularly having high infrared emittance by anodizing an aluminum or aluminum alloy substrate surface in an aqueous sulfuric acid solution at elevated temperature and by a step-wise current density procedure, followed by sealing the resulting anodized surface. In a preferred embodiment the aluminum or aluminum alloy substrate is first alkaline cleaned and then chemically brightened in an acid bath The resulting cleaned substrate is anodized in a 15% by weight sulfuric acid bath maintained at a temperature of 30.degree. C. Anodizing is carried out by a step-wise current density procedure at 19 amperes per square ft. (ASF) for 20 minutes, 15 ASF for 20 minutes and 10 ASF for 20 minutes. After anodizing the sample is sealed by immersion in water at 200.degree. F. and then air dried. The resulting coating has a high infrared emissivity of about 0.92 and a solar absorptivity of about 0.2, for a 5657 aluminum alloy, and a relatively thick anodic coating of about 1 mil.

  1. Corrosion-Activated Micro-Containers for Environmentally Friendly Corrosion Protective Coatings

    NASA Technical Reports Server (NTRS)

    Li, Wenyan; Buhrow, J. W.; Zhang, X.; Johnsey, M. N.; Pearman, B. P.; Jolley, S. T.; Calle, L. M.

    2016-01-01

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

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

    SciTech Connect

    Thomas M. Lillo

    2011-04-01

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

  3. Processing and Characterization of Functionally Graded Hydroxyapatite Coatings for Biomedical Implants

    NASA Astrophysics Data System (ADS)

    Bai, Xiao

    Hydroxyapatite [Ca10(PO4)6(OH) 2, HA] has been widely applied as a coating on various biomedical bone/dental implants to improve biocompatibility and bioactivity. It has been observed that primary reasons leading to implantation failure of commercial HA coated implants processed by plasma spraying are the poor mechanical properties of coatings and infections accompanied by implantation. It has been also reported an ideal coating should be able to stimulate new bone growth at the initial stage of implantation and stay stable both mechanically and chemically thereafter. This research has investigated a functionally graded hydroxyapatite (FGHA) coating that is capable of improving the stability of implants, facilitating recovery, and preventing infections after implantation. A series of FGHA coatings with incorporated Ag 0 ˜ 13.53 wt. % has been deposited onto Ti substrate using ion beam assisted deposition (IBAD) with in-situ heat treatment. The compositional, microstructural, mechanical, and biological properties of coatings have been analyzed via various tests. The relationship among processing parameters, coating properties and biological behaviors has been established and the processing parameters for processing FGHA coatings with/without incorporated Ag have been optimized. Microstructure observations of coating cross section via transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) for set temperature coatings deposited at 450°C ˜ 750°C reveals that in-situ substrate temperature is the primary factor controlling the crystallinity of the coatings. The microstructure observation of cross section via TEM/STEM for both FGHA coatings with/without incorporated Ag has shown that coatings are dense and have a gradually decreased crystallinity from substrate/coating interface to top surface. In particular, the interface has an atomically intermixed structure; the region near the interface has a columnar grain structure whereas

  4. Coated armor system and process for making the same

    DOEpatents

    Chu, Henry S.; Lillo, Thomas M.; McHugh, Kevin M.

    2010-11-23

    An armor system and method involves providing a core material and a stream of atomized coating material that comprises a liquid fraction and a solid fraction. An initial layer is deposited on the core material by positioning the core material in the stream of atomized coating material wherein the solid fraction of the stream of atomized coating material is less than the liquid fraction of the stream of atomized coating material on a weight basis. An outer layer is then deposited on the initial layer by positioning the core material in the stream of atomized coating material wherein the solid fraction of the stream of atomized coating material is greater than the liquid fraction of the stream of atomized coating material on a weight basis.

  5. Patterned Thermoresponsive Microgel Coatings for Noninvasive Processing of Adherent Cells.

    PubMed

    Uhlig, Katja; Wegener, Thomas; He, Jian; Zeiser, Michael; Bookhold, Johannes; Dewald, Inna; Godino, Neus; Jaeger, Magnus; Hellweg, Thomas; Fery, Andreas; Duschl, Claus

    2016-03-14

    Cultivation of adherently growing cells in artificial environments is of utmost importance in medicine and biotechnology to accomplish in vitro drug screening or to investigate disease mechanisms. Precise cell manipulation, like localized control over adhesion, is required to expand cells, to establish cell models for novel therapies and to perform noninvasive cell experiments. To this end, we developed a method of gentle, local lift-off of mammalian cells using polymer surfaces, which are reversibly and repeatedly switchable between a cell-attractive and a cell-repellent state. This property was introduced through micropatterned thermoresponsive polymer coatings formed from colloidal microgels. Patterning was obtained through automated nanodispensing or microcontact printing, making use of unspecific electrostatic interactions between microgels and substrates. This process is much more robust against ambient conditions than covalent coupling, thus lending itself to up-scaling. As an example, wound healing assays were accomplished at 37 °C with highly increased precision in microfluidic environments.

  6. Parameters Influencing the Photocatalytic Activity of Suspension-Sprayed TiO2 Coatings

    NASA Astrophysics Data System (ADS)

    Toma, Filofteia-Laura; Berger, Lutz-Michael; Shakhverdova, Irina; Leupolt, Beate; Potthoff, Annegret; Oelschlägel, Kathrin; Meissner, Tobias; Gomez, José Antonio Ibáñez; de Miguel, Yolanda

    2014-10-01

    Photocatalytic properties of titania have been studied very intensively for a variety of applications, including air and water purification. In order to clarify the influence of the phase composition and other parameters, thermal spraying with suspensions was applied to produce photocatalytically active titania coatings starting from two commercially available anatase and rutile submicron powders. Aqueous suspensions containing 40% solids by weight were sprayed with an HVOF process using ethylene as the fuel gas. The spray parameters were chosen in order to produce mechanically stable coatings and to preserve a high content of the initial crystalline phases of the powders. The coating microstructures, phase compositions, and surface properties were characterized. The photocatalytic performance was evaluated by degradation of the pink dye Rhodamine B (RB) using two techniques: degradation of an aqueous solution of RB and discoloration of impregnated RB. All the coatings exhibited photocatalytic activity to varying degrees, depending on the phase composition as well as other factors, namely, the coating microstructure, surface morphology, surface hydroxylation, light absorption, and interaction with the pollutant.

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

    SciTech Connect

    Thomas Lillo; Richard Wright

    2009-05-01

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

  8. Thin film coating process using an inductively coupled plasma

    DOEpatents

    Kniseley, Richard N.; Schmidt, Frederick A.; Merkle, Brian D.

    1990-01-30

    Thin coatings of normally solid materials are applied to target substrates using an inductively coupled plasma. Particles of the coating material are vaporized by plasma heating, and pass through an orifice to a first vacuum zone in which the particles are accelerated to a velocity greater than Mach 1. The shock wave generated in the first vacuum zone is intercepted by the tip of a skimmer cone that provides a second orifice. The particles pass through the second orifice into a second zone maintained at a higher vacuum and impinge on the target to form the coating. Ultrapure coatings can be formed.

  9. Simulation of a tablet coating process at different scales using DEM.

    PubMed

    Boehling, P; Toschkoff, G; Just, S; Knop, K; Kleinebudde, P; Funke, A; Rehbaum, H; Rajniak, P; Khinast, J G

    2016-10-10

    Spray coating of tablets is an important unit operation in the pharmaceutical industry and is mainly used for modified release, enteric protection, better appearance and brand recognition. It can also be used to apply an additional active pharmaceutical ingredient to the tablet core. Scale-up of such a process is an important step in commercialization. However, scale-up is not trivial and frequently, at manufacturing scales the required coating quality cannot be reached. Thus, we propose a method where laboratory experiments are carried out, yet scale-up is done via computational methods, i.e., by extrapolating results to larger scales. In the recent years, the Discrete Element Method (DEM) has widely been used to simulate tablet behavior in a laboratory scale drum coater. Due the increasing computational power and more sophisticated DEM algorithms, it has become possible to simulate millions of particles on regular PCs and model industrial scale tablet coating devices. In this work, simulations were performed on the laboratory, pilot and industrial scales and DEM was used to study how different scale-up rules influence the bed behavior on larger scales. The material parameters of the tablets were measured in the laboratory and a glued sphere approach was applied to model the tablet shape. The results include a vast amount of qualitative and quantitative data at the different scales. In conclusion, the evolution of the inter-tablet coating variation for the different scales and process parameters is presented. The results suggest that keeping the Froude number constant during the scale up process leads to faster processes as the cycle time is shorter and the spray residence time is more uniform when compared to keeping the circumferential velocity constant.

  10. Ion-plasma processes of the production of diffusion aluminide coatings

    NASA Astrophysics Data System (ADS)

    Muboyadzhyan, S. A.

    2010-03-01

    A novel ion-plasma process for ecologically safe formation of diffusion aluminide coatings on a substrate made of a superalloy, which has advantages as compared to the well-known thermodiffusion processes of their production, is described. The ion-plasma process is shown to provide the formation of diffusion aluminide coatings on the surface of a superalloy substrate according to various technologies. Owing to alloying with one or several elements from the series Y, Si, Cr, Hf, B, Co, etc., ion-plasma diffusion coatings have higher protective properties than analogous coatings produced by the traditional methods of powder, slip, and gas-circulating aluminizing.

  11. Experimental and thermodynamic considerations of Mg2Si coatings deposited by pack cementation process

    NASA Astrophysics Data System (ADS)

    Stathokostopoulos, D.; Tsipas, S. A.; Chaliampalias, D.; Pavlidou, E.; Hatzikraniotis, E.; Paraskevopoulos, K. M.; Vourlias, G.

    2017-01-01

    Magnesium disilicide is a narrow gap semiconductor which can be used in several applications such as thermoelectric materials, optoelectronic devices and batteries. It has attracted special attraction because of its low cost and non-toxicity. In the herein examination the formation of this compound is investigated by a simple, one-stage process which is pack cementation. Particularly, the effect of deposition time, activator and donor material concentration was examined. Mg2Si was formed in every case without the presence of other compounds as referred to be present when formed with other coating procedures which have higher cost and are very sophisticated. The examined parameters were found to have effect only on the coating thickness up to a certain value. Moreover, the experimental results confirmed the theoretical thermodynamic calculations performed for this case.

  12. Lectin coated MgO nanoparticle: its toxicity, antileishmanial activity, and macrophage activation.

    PubMed

    Jebali, Ali; Hekmatimoghaddam, Seyedhossein; Kazemi, Bahram; Allaveisie, Azra; Masoudi, Alireza; Daliri, Karim; Sedighi, Najme; Ranjbari, Javad

    2014-10-01

    The purpose of this research was to evaluate toxicity of uncoated magnesium oxide nanoparticles (MgO NPs), MgO NPs coated with Peanut agglutinin (PNA) lectin, and PNA alone on the promastigotes of Leishmania major (L. major) and macrophages of BALB/c mice. On the other hand, antileishmanial property of uncoated MgO NPs, lectin coated MgO NPs, and PNA lectin alone was evaluated, and also macrophage activation was investigated after treatment with these materials by measurement of nitrite, H2O2, and some interleukins. This study showed that PNA lectin and lectin coated MgO NPs had approximately no toxicity on L. major and macrophages, but some toxic effects were observed for uncoated MgO NPs, especially at concentration of 500 µg/mL. Interestingly, lectin coated MgO NPs had the highest antileishmanial activity and macrophage activation, compared with uncoated MgO NPs and PNA lectin.

  13. Multilayer hydrogel coatings to combine hemocompatibility and antimicrobial activity.

    PubMed

    Fischer, Marion; Vahdatzadeh, Maryam; Konradi, Rupert; Friedrichs, Jens; Maitz, Manfred F; Freudenberg, Uwe; Werner, Carsten

    2015-07-01

    While silver-loaded catheters are widely used to prevent early-onset catheter-related infections [1], long term antimicrobial protection of indwelling catheters remains to be achieved [2] and antiseptic functionalization of coatings often impairs their hemocompatibility characteristics. Therefore, this work aimed to capitalize on the antimicrobial properties of silver nanoparticles, incorporated in anticoagulant poly(ethylene glycol) (PEG)-heparin hydrogel coatings [3] on thermoplastic polyurethane materials. For prolonged antimicrobial activity, the silver-containing starPEG-heparin hydrogel layers were shielded with silver-free hydrogel layers of otherwise similar composition. The resulting multi-layered gel coatings showed long term antiseptic efficacy against Escherichia coli and Staphylococcus epidermidis strains in vitro, and similarly performed well when incubated with freshly drawn human whole blood with respect to hemolysis, platelet activation and plasmatic coagulation. The introduced hydrogel multilayer system thus offers a promising combination of hemocompatibility and long-term antiseptic capacity to meet an important clinical need.

  14. Processing, structure, and properties of nanostructured multifunctional tribological coatings.

    PubMed

    Lin, Jianliang; Park, In-Wook; Mishra, Brajendra; Pinkas, Malki; Moore, John J; Anton, Jennifer M; Kim, Kwang Ho; Voevodin, Andrey A; Levashov, Evgeny A

    2009-07-01

    Nanostructured, nanocomposite binary (TiC-a:C), ternary (Cr-Al-N), quaternary (Ti-B-C-N) and quinternary (Ti-Si-B-C-N) multicomponent films have been deposited using unbalanced magnetron sputtering (UBMS) and closed field unbalanced magnetron sputtering (CFUBMS) from both elemental and composite targets. Approaches to control the film chemistry, volume fraction and size of the multicomponent species, and pulsed ion energy (ion flux) bombardment to tailor the structure and properties of the films for specific tribological applications, e.g., low friction coefficient and low wear rate, are emphasized. The synthesized films are characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), nanoindentation, and microtribometry. The relationships between processing parameters (pulsed ion energy and ion flux), thin film microstructure, mechanical and tribological properties are being investigated in terms of the nanocrystalline-nanocrystalline and nanocrystalline-amorphous composite thin film systems that are generated. In the Ti-Si-B-C-N films, nanocomposites of solid solutions, e.g., nanosized (Ti,C,N)B2 and Ti(C,N) crystallites are embedded in an amorphous TiSi2 and SiC matrix including some carbon, SiB4, BN, CN(x), TiO2 and B2O3 components. The Ti-Si-B-C-N coating with up to 150 W Si target power exhibited a hardness of about 35 GPa, a high H/E ratio of 0.095, and a low wear rate of from approximately 3 to approximately 10 x 10(-6) mm3/(Nm). In another aspect, using increased ion energy and ion flux, which are generated by pulsing the power of the target(s) in a closed field arrangement, to provide improved ion bombardment on tailoring the structure and properties of TiC-a:C and Cr-Al-N coatings are demonstrated. It was found that highly energetic species (up to hundreds eV) were found in the plasma by pulsing the power of the target(s) during magnetron sputtering

  15. Tribological coating of titanium alloys by laser processing

    NASA Astrophysics Data System (ADS)

    Pang, Wang

    Titanium-based alloys have been used for aerospace materials for many years. Recently, these alloys are now being increasingly considered for automotive, industrial and consumer applications. Their excellent creep resistance, corrosion resistance and relative higher specific strength ratio are attractive for many applications. However, the main obstacle for the wide adoption of Ti alloys in various industries is their poor tribological properties. In slide wear, Ti deforms and adhesive wear readily occurs. Their poor tribological properties are mainly due to low hardness and absolute values of tensile and shear strength. Different surface modification techniques have been studied in order to improve the tribological characteristics of Ti alloys, i.e. PVD, nitrding, carburizing, boriding, plating etc. Coatings produced by these techniques have their own limitations such as thermal distortion and grain growth. A different approach is to introduce hard particles in the Ti alloy matrix to form a MMC coating, which has tailor-made hardness and wear resistance properties. Laser cladding or laser alloying techniques facilitate the fabrication of surface MMC on Ti alloys without thermal distortion to the substrate. In this project, the fabrication of hard and wear resistant layers of metal matrix composite on titanium alloys substrate by laser surface alloying was investigated. Powder mixtures of Mo and WC were used to form the MMC layer. By optimizing the processing parameters and pre-placed powder mixture compositions, surface MMC of different properties have been successfully fabricated on CP-Ti and Ti6A14V respectively. The structure and characteristics of the MMC surface were investigated by metallography, SEM, XRD, and E-DAX. It was found that the hardness of the laser alloyed Mo/WC MMC surface was 300% higher than that of the CP-Ti substrate Excellent metallurgical bonding with the MMC layer of the substrate has been achieved. The relative kinetic frictional tests

  16. Activation studies of NEG coatings by surface techniques

    SciTech Connect

    Sharma, R. K.; Jagannath,; Bhushan, K. G.; Gadkari, S. C.; Mukund, R.; Gupta, S. K.

    2013-02-05

    NEG (Non Evaporable Getters)materials in the form of ternary alloy coatings have many benefits compare to traditional bare surfaces such as Extreme high vacuum(XHV), lower secondary electron yield(SEY), low photon desorption cofficient. The extreme high vacuum (pressure > 10{sup -10} mbar) is very useful to the study of surfaces of the material, for high energy particle accelerators(LHC, Photon Factories), synchrotrons (ESRF, Ellectra) etc. Low secondary electron yield leads to better beam life time. In LHC the pressure in the interaction region of the two beams is something of the order of 10{sup -12} mbar. In this paper preparation of the coatings and their characterization to get the Activation temperature by using the surface techniques XPS, SEM and SIMS has been shown.

  17. Mathematical model to predict coat weight variability in a pan coating process.

    PubMed

    Joglekar, Anand; Joshi, Nitin; Song, Yongxin; Ergun, James

    2007-01-01

    The variability in drug release from extended-release products is strongly dependant on the tablet coat weight variability. A mechanistic model to predict the coefficient of variation (CV) of the tablet coat weight is proposed. Although the main assumption is complete random mixing, the model also assumes that each tablet spends a fixed amount of time in the coating zone and receives a fixed amount of coating in each coating event. The number of coating events that each tablet undergoes is given by the binomial distribution. The model predicts that the coat weight CV will depend on the projected area of the tablet (a), velocity of the tablet in the spray zone (V), the number of spray guns (N(spray)), the length of the spray zone (L), the total number of tablets (N), and the total spray time (t). The CV is estimated to be equal to 100 square root of (an)/VLtN(spray). The overall R2 of the model for a side vented pan was 86% with a prediction error standard deviation of 1.3%. Two empirical correction factors were identified to explain the offset.

  18. Investigation of PACVD protective coating processes using advanced diagnostics techniques

    SciTech Connect

    Roman, W.C.

    1993-05-07

    Objective is to understand the mechanisms governing nonequilibrium plasma atomistic or molecular deposition of hard face coatings. Laser diagnostic methods include coherent anti-Stokes Raman spectroscopy (CARS) and laser-induced fluorescence. TiB[sub 2] and diamonds were used as the hard face coating materials. Diborane was used as precursor to TiB[sub 2].

  19. Development of a dry coating process for broadloom carpet. Final report

    SciTech Connect

    Not Available

    1983-04-08

    The DASH dry-applied thermoplastic fusion coating process has demonstrated energy savings up to 80%, labor savings up to 50% and coating material cost savings up to 20%. The DASH process generates coatings with characteristics superior to those of latex coatings on most carpets including: better tuft bind, resistance to cleaning agents and moisture, lower applied weights to produce equal or better physical characteristics, and a definitely superior adhesion of the secondary backing. Materials have been obtained, tested and identified as to those which provide the mix formulation ingredients to provide acceptable physical properties. Another area of increasing concern is smoke emission. It is in this area the DASH coating process remains superior. With a mark of 450 and below considered passing and 200 considered to be excellent, the DASH coating has remained well under 100 and has reached as low as 14.

  20. Processing and properties of chromate-free conversion coatings on aluminum

    SciTech Connect

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

    1994-12-31

    A conversion coating method has been developed based on precipitation of Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}3H{sub 2}O from alkaline lithium salt solutions. The process is procedurally similar to chromate conversion coating but does not use or produce hazardous chemicals. The coating that forms is polycrystalline, continuous and conformal. The coating meets the MIL-C-5541E corrosion resistance, electrical contact resistance and paint adhesion requirements for certain aluminum alloys, but does not match the levels of performance exhibited by chromate conversion coatings. In this paper, methods for producing the coating are described. Corrosion resistance has been characterized using electrochemical impedance spectroscopy and salt spray exposure. The structural, compositional and property changes attending post-coating thermal exposure are discussed. Performance in standardized corrosion, electrical and paint adhesion tests is also presented.

  1. Process for producing radiation-induced self-terminating protective coatings on a substrate

    DOEpatents

    Klebanoff, Leonard E.

    2001-01-01

    A gas and radiation are used to produce a protective coating that is substantially void-free on the molecular scale, self-terminating, and degradation resistant. The process can be used to deposit very thin (.apprxeq.5-20 .ANG.) coatings on critical surfaces needing protection from degradative processes including, corrosion and contamination.

  2. Influence of sample composition and processing parameters on the UV cure of clear coatings

    NASA Astrophysics Data System (ADS)

    Ruiz, C. S. B.; Machado, L. D. B.; Volponi, J. E.; Pino, E. S.

    2003-08-01

    Photocurable systems consist of functional macromolecules, which undergo polymerization and a photoinduced crosslinking reaction under UV irradiation. Radiation-curable coatings have gained importance because they are environmentally friendly and save more energy than conventional heat-curable processes. The performance of UV-curable coatings depends on their formulation and cure quality. The quality of UV radiation cure depends on lamp characteristics, photoinitiator (PI) content, film thickness, curing environment, substrate and temperature. The aim of this study was to evaluate the influence of coating thickness and UV radiation dose, as well as coating characteristics such as PI content and stabilizer additive composition, on the curing process.

  3. Failure processes within ceramic coatings at high temperatures

    NASA Technical Reports Server (NTRS)

    Berndt, Christopher

    1989-01-01

    Plasma sprayed coatings have a complex structure which is produced by the overlaying of many molten or semi-molten particles in the diameter range of 20 to 120 microns. The failure behavior of coatings has been characterized by using acoustic emission (AE) methodology. Coatings of NiCrAlY bond coat with a zirconia-12 wt pct yttria overlay were applied to disk-shaped specimens of U-700 alloy. A waveguide of 1-mm diameter platinum was TlG welded to the specimen and allowed it to be suspended in a tubular furnace. The specimen was thermally cycled to 1150 C and the AE monitored. Analyses have been carried out with the aim of establishing parameters which are related to the crack size population. These studies have been used to postulate types of cracking mechanisms which may occur in plasma sprayed coatings during thermal cycling. It is shown that microcracking gave rise to a large amount of AE. However, this coating still survived more thermal cycles than a coating which exhibited macrocracking events.

  4. Corrosion processes of physical vapor deposition-coated metallic implants.

    PubMed

    Antunes, Renato Altobelli; de Oliveira, Mara Cristina Lopes

    2009-01-01

    Protecting metallic implants from the harsh environment of physiological fluids is essential to guaranteeing successful long-term use in a patient's body. Chemical degradation may lead to the failure of an implant device in two different ways. First, metal ions may cause inflammatory reactions in the tissues surrounding the implant and, in extreme cases, these reactions may inflict acute pain on the patient and lead to loosening of the device. Therefore, increasing wear strength is beneficial to the performance of the metallic implant. Second, localized corrosion processes contribute to the nucleation of fatigue cracks, and corrosion fatigue is the main reason for the mechanical failure of metallic implants. Common biomedical alloys such as stainless steel, cobalt-chrome alloys, and titanium alloys are prone to at least one of these problems. Vapor-deposited hard coatings act directly to improve corrosion, wear, and fatigue resistances of metallic materials. The effectiveness of the corrosion protection is strongly related to the structure of the physical vapor deposition layer. The aim of this paper is to present a comprehensive review of the correlation between the structure of physical vapor deposition layers and the corrosion properties of metallic implants.

  5. Research on chemical vapor deposition processes for advanced ceramic coatings

    NASA Technical Reports Server (NTRS)

    Rosner, Daniel E.

    1993-01-01

    Our interdisciplinary background and fundamentally-oriented studies of the laws governing multi-component chemical vapor deposition (VD), particle deposition (PD), and their interactions, put the Yale University HTCRE Laboratory in a unique position to significantly advance the 'state-of-the-art' of chemical vapor deposition (CVD) R&D. With NASA-Lewis RC financial support, we initiated a program in March of 1988 that has led to the advances described in this report (Section 2) in predicting chemical vapor transport in high temperature systems relevant to the fabrication of refractory ceramic coatings for turbine engine components. This Final Report covers our principal results and activities for the total NASA grant of $190,000. over the 4.67 year period: 1 March 1988-1 November 1992. Since our methods and the technical details are contained in the publications listed (9 Abstracts are given as Appendices) our emphasis here is on broad conclusions/implications and administrative data, including personnel, talks, interactions with industry, and some known applications of our work.

  6. Impact of Processing Conditions on Inter-tablet Coating Thickness Variations Measured by Terahertz In-Line Sensing.

    PubMed

    Lin, Hungyen; May, Robert K; Evans, Michael J; Zhong, Shuncong; Gladden, Lynn F; Shen, Yaochun; Zeitler, J Axel

    2015-08-01

    A novel in-line technique utilising pulsed terahertz radiation for direct measurement of the film coating thickness of individual tablets during the coating process was previously developed and demonstrated on a production-scale coater. Here, we use this technique to monitor the evolution of tablet film coating thickness and its inter-tablet variability during the coating process under a number of different process conditions that have been purposefully induced in the production-scale coating process. The changes that were introduced to the coating process include removing the baffles from the coater, adding uncoated tablets to the running process, halting the drum, blockage of spray guns and changes to the spray rate. The terahertz sensor was able to pick up the resulting changes in average coating thickness in the coating drum and we report the impact of these process changes on the resulting coating quality.

  7. High Temperature Oxidation Behavior of HVOF-sprayed Coatings for Use in Thixoextrusion Processes

    SciTech Connect

    Picas, J. A.; Punset, M.; Menargues, S.; Campillo, M.; Baile, M. T.; Forn, A.

    2011-05-04

    The dies used for the thixoextrusion of steels have to be capable of withstanding complex thermal and mechanical loads, while giving a sufficient wear resistance against abrasion and adhesion at very high temperatures. In order to improve the wear resistance and reduce the heating of the extrusion die it can be protected with a hard cermet coating. The purpose of this work is to study the high-temperature performance of CrC-CoNiCrAlY coating and explore the potential application of this coating to improve dies used in thixoextrusion processes. A two-layer 75CrC-25CoNiCrAlY coating with a CoNiCrAlY bond-coating was fabricated by the HVOF thermal spray process on a steel substrate. Coatings were heat-treated at a range of temperatures between 900 deg. C and 1100 deg. C. The microstructural characterization of the coatings before and after heat treatment was conducted by scanning electron microscopy (SEM) and an X-ray diffractometer (XRD). The mechanical properties of coatings were determined as a function of the temperature of heat treatment. The bond coat effect on the thermal shock resistance of CrC-CoNiCrAlY coating was analyzed.

  8. Scale Up of Pan Coating Process Using Quality by Design Principles.

    PubMed

    Agrawal, Anjali M; Pandey, Preetanshu

    2015-11-01

    Scale up of pan coating process is of high importance to the pharmaceutical and food industry. The number of process variables and their interdependence in a pan coating process can make it a rather complex scale-up problem. This review discusses breaking down the coating process variables into three main categories: pan-related, spray-related, and thermodynamic-related factors. A review on how to scale up each of these factors is presented via two distinct strategies--"macroscopic" and "microscopic" scale-up. In a Quality by Design paradigm, where an increased process understanding is required, there is increased emphasis on "microscopic" scale-up, which by definition ensures a more reproducible process and thereby robust scale-up. This article also reviews the various existing and new modeling and process analytical technology tools that can provide additional information to facilitate a more fundamental understanding of the coating process.

  9. Superhydrophobic chitosan-based coatings for textile processing

    NASA Astrophysics Data System (ADS)

    Ivanova, N. A.; Philipchenko, A. B.

    2012-12-01

    A simple method to design the superhydrophobic anti-bacterial textile for biomedical applications was developed. For the coating formulation the spraying of nanoparticles dispersion over the textile sample was applied, allowing the way to get multiscale textured layer on a top of cotton fabric. The anti-bacterial functionality of coating is supported by using chitosan-based nanoparticles. In our approach the fabrication of nanoparticles was based on electrostatic interaction between amine group of chitosan and negatively charged fluoroanion. It was demonstrated that the relative number of fluoroanions per elementary unit of chitosan plays the crucial role in the structure of aggregates in the coating and its wettability as well as in durability of coatings in contact with aqueous media.

  10. Research of surface activating influence on formation of adhesion between gas-thermal coating and steel substrate

    NASA Astrophysics Data System (ADS)

    Kovalevskaya, Z.; Klimenov, V.; Zaitsev, K.

    2015-09-01

    Estimation of influence of physical and thermal activating on adhesion between steel substrates and thermal coatings has been performed. The substrates with surfaces obtained by and ultrasonic surface plastic deformation were used. To evaluate physical activating, preheating of the substrates to 600°C was performed. To evaluate the effect of thermal activating, the substrate surfaces after interfacial detachment were examined. Bonded areas on the substrate surfaces were measured by means of optical profilometry. The experiments have shown that surface physical activating is the main factor in formation of the adhesive bond between the coating and the substrate processed with the proposed methods.

  11. Processing-structure-property relationships in electron beam physical vapor deposited yttria stabilized zirconia coatings

    SciTech Connect

    Rao, D. Srinivasa; Valleti, Krishna; Joshi, S. V.; Janardhan, G. Ranga

    2011-05-15

    The physical and mechanical properties of yttria stabilized zirconia (YSZ) coatings deposited by the electron beam physical vapor deposition technique have been investigated by varying the key process variables such as vapor incidence angle and sample rotation speed. The tetragonal zirconia coatings formed under varying process conditions employed were found to have widely different surface and cross-sectional morphologies. The porosity, phase composition, planar orientation, hardness, adhesion, and surface residual stresses in the coated specimens were comprehensively evaluated to develop a correlation with the process variables. Under transverse scratch test conditions, the YSZ coatings exhibited two different crack formation modes, depending on the magnitude of residual stress. The influence of processing conditions on the coating deposition rate, column orientation angle, and adhesion strength has been established. Key relationships between porosity, hardness, and adhesion are also presented.

  12. Effect of silicon carbide ceramic coating process on the mirror surface quality

    NASA Astrophysics Data System (ADS)

    Wang, Peipei; Wang, Li; Wang, Gang; Bai, Yunli; Wang, Peng; Xiao, Zhenghang

    2016-10-01

    Silicon carbide, as a new reflector material, its excellent physical and chemical properties has been widely recognized by the industry. In order to make SiC mirror better used in space optical system, we used digital coating equipment during its coating process. By using ion-assisted electron evaporation method, we got a complete metal reflective film system on the surface of finely polished silicon carbide mirror. After automated coating process, by adjusting the coating parameters during the process, the surface roughness of silicon carbide improved from 7.8 nm to 5.1 nm, and the average optical reflectance of the surface reached 95% from visible to near-infrared. The metal reflective film system kept well after annealing and firmness test. As a result, the work of this paper will provide an important reference for high-precision coating process on large diameter SiC mirror.

  13. In-Line Monitoring of a Pharmaceutical Pan Coating Process by Optical Coherence Tomography.

    PubMed

    Markl, Daniel; Hannesschläger, Günther; Sacher, Stephan; Leitner, Michael; Buchsbaum, Andreas; Pescod, Russel; Baele, Thomas; Khinast, Johannes G

    2015-08-01

    This work demonstrates a new in-line measurement technique for monitoring the coating growth of randomly moving tablets in a pan coating process. In-line quality control is performed by an optical coherence tomography (OCT) sensor allowing nondestructive and contact-free acquisition of cross-section images of film coatings in real time. The coating thickness can be determined directly from these OCT images and no chemometric calibration models are required for quantification. Coating thickness measurements are extracted from the images by a fully automated algorithm. Results of the in-line measurements are validated using off-line OCT images, thickness calculations from tablet dimension measurements, and weight gain measurements. Validation measurements are performed on sample tablets periodically removed from the process during production. Reproducibility of the results is demonstrated by three batches produced under the same process conditions. OCT enables a multiple direct measurement of the coating thickness on individual tablets rather than providing the average coating thickness of a large number of tablets. This gives substantially more information about the coating quality, that is, intra- and intertablet coating variability, than standard quality control methods.

  14. Polyacrylonitrile nanofibers coated with silver nanoparticles using a modified coaxial electrospinning process

    PubMed Central

    Yu, Deng-Guang; Zhou, Jie; Chatterton, Nicholas P; Li, Ying; Huang, Jing; Wang, Xia

    2012-01-01

    Background The objective of this investigation was to develop a new class of antibacterial material in the form of nanofibers coated with silver nanoparticles (AgNPs) using a modified coaxial electrospinning approach. Through manipulation of the distribution on the surface of nanofibers, the antibacterial effect of Ag can be improved substantially. Methods Using polyacrylonitrile (PAN) as the filament-forming polymer matrix, an electrospinnable PAN solution was prepared as the core fluid. A silver nitrate (AgNO3) solution was exploited as sheath fluid to carry out the modified coaxial electrospinning process under varied sheath-to-core flow rate ratios. Results Scanning electron microscopy and transmission electron microscopy demonstrated that the sheath AgNO3 solution can take a role in reducing the nanofibers’ diameters significantly, a sheath-to-core flow rate ratio of 0.1 and 0.2 resulting in PAN nanofibers with diameters of 380 ± 110 nm and 230 ± 70 nm respectively. AgNPs are well distributed on the surface of PAN nanofibers. The antibacterial experiments demonstrated that these nanofibers show strong antimicrobial activities against Bacillus subtilis Wb800, and Escherichia coli dh5α. Conclusion Coaxial electrospinning with AgNO3 solution as sheath fluid not only facilitates the electrospinning process, providing nanofibers with reduced diameters, but also allows functionalization of the nanofibers through coating with functional ingredients, effectively ensuring that the active antibacterial component is on the surface of the material, which leads to enhanced activity. We report an example of the systematic design, preparation, and application of a novel type of antibacterial material coated with AgNPs via a modified coaxial electrospinning methodology. PMID:23166437

  15. Understanding Solidification of Polythiophene Thin Films during Spin-Coating: Effects of Spin-Coating Time and Processing Additives

    NASA Astrophysics Data System (ADS)

    Na, Jin Yeong; Kang, Boseok; Sin, Dong Hun; Cho, Kilwon; Park, Yeong Don

    2015-08-01

    Spin-coating has been used extensively in the fabrication of electronic devices; however, the effects of the processing parameters have not been fully explored. Here, we systematically characterize the effects of the spin-coating time on the microstructure evolution during semiconducting polymer solidification in an effort to establish the relationship between this parameter and the performances of the resulting polymer field-effect transistors (FETs). We found that a short spin-coating time of a few seconds dramatically improve the morphology and molecular order in a conjugated polymer thin film because the π-π stacking structures formed by the polymer molecules grow slowly and with a greater degree of order due to the residual solvent present in the wet film. The improved ordering is correlated with improved charge carrier transport in the FETs prepared from these films. We also demonstrated the effects of various processing additives on the resulting FET characteristics as well as on the film drying behavior during spin-coating. The physical properties of the additives are found to affect the film drying process and the resulting device performance.

  16. Understanding Solidification of Polythiophene Thin Films during Spin-Coating: Effects of Spin-Coating Time and Processing Additives

    PubMed Central

    Na, Jin Yeong; Kang, Boseok; Sin, Dong Hun; Cho, Kilwon; Park, Yeong Don

    2015-01-01

    Spin-coating has been used extensively in the fabrication of electronic devices; however, the effects of the processing parameters have not been fully explored. Here, we systematically characterize the effects of the spin-coating time on the microstructure evolution during semiconducting polymer solidification in an effort to establish the relationship between this parameter and the performances of the resulting polymer field-effect transistors (FETs). We found that a short spin-coating time of a few seconds dramatically improve the morphology and molecular order in a conjugated polymer thin film because the π-π stacking structures formed by the polymer molecules grow slowly and with a greater degree of order due to the residual solvent present in the wet film. The improved ordering is correlated with improved charge carrier transport in the FETs prepared from these films. We also demonstrated the effects of various processing additives on the resulting FET characteristics as well as on the film drying behavior during spin-coating. The physical properties of the additives are found to affect the film drying process and the resulting device performance. PMID:26299676

  17. Understanding Solidification of Polythiophene Thin Films during Spin-Coating: Effects of Spin-Coating Time and Processing Additives.

    PubMed

    Na, Jin Yeong; Kang, Boseok; Sin, Dong Hun; Cho, Kilwon; Park, Yeong Don

    2015-08-24

    Spin-coating has been used extensively in the fabrication of electronic devices; however, the effects of the processing parameters have not been fully explored. Here, we systematically characterize the effects of the spin-coating time on the microstructure evolution during semiconducting polymer solidification in an effort to establish the relationship between this parameter and the performances of the resulting polymer field-effect transistors (FETs). We found that a short spin-coating time of a few seconds dramatically improve the morphology and molecular order in a conjugated polymer thin film because the π-π stacking structures formed by the polymer molecules grow slowly and with a greater degree of order due to the residual solvent present in the wet film. The improved ordering is correlated with improved charge carrier transport in the FETs prepared from these films. We also demonstrated the effects of various processing additives on the resulting FET characteristics as well as on the film drying behavior during spin-coating. The physical properties of the additives are found to affect the film drying process and the resulting device performance.

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

    PubMed

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

    2016-12-01

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

  19. Optimization of an aqueous tablet-coating process containing carboxymethylated Cassia fistula gum.

    PubMed

    Rai, Parshu Ram; Tiwary, Ashok Kumar; Rana, Vikas

    2012-06-01

    The present investigation was aimed at developing and optimizing a simple aqueous tablet-coating formulation and its process. 5-Fluorouracil (5-FU) was used to ascertain the relative lipophilic/hydrophilic behavior of the coating system. Optimization was performed by evaluating the adhesive force strength and cohesive force strength of the tablet coat using a texture analyzer. The in vitro release of 5-FU was found to decrease with an increase in (tablet surface-coat) adhesive force strength. The (tablet-tablet) cohesive force strength was reduced by the addition of magnesium silicate to the coating solution. The addition of magnesium silicate (0.2% w/v) to the carboxymethyl Cassia fistula gum-chitosan (CCG-CH) coating surface significantly inhibited the release of 5-FU possibly due to an increase in the hydrophobic character of the coated tablet surface. This was possible by coating cohesive force strength reduction coating compositions (CCG-CH (70:30) and 0.3% magnesium silicate). Further, the FTIR-ATR and DSC analyses suggested the pivotal role of magnesium silicate in modifying the release of 5-FU from CCG-CH-coated tablets due to hydrogen bonding of its Si-O-Si or Mg-O groups with -OH moieties of CCG-CH.

  20. Simulation of Energy Savings in Automotive Coatings Processes

    NASA Astrophysics Data System (ADS)

    Gerini Romagnoli, Marco

    Recently, the automakers have become more and more aware of the environmental and economic impact of their manufacturing processes. The paint shop is the largest energy user in a vehicle manufacturing plant, and one way to reduce costs and energy usage is the optimization of this area. This project aims at providing a tool to model and simulate a paint shop, in order to run and analyze some scenarios and case studies, helping to take strategic decisions. Analytical computations and real data were merged to build a tool that can be used by FCA for their Sterling Heights plant. Convection and conduction heat losses were modeled for the dip processes and the ovens. Thermal balances were used to compute the consumptions of booths, decks and ovens, while pump and fan energy consumptions were modeled for each sub-process. The user acts on a calendar, scheduling a year of production, and the model predicts the energy consumption of the paint shop. Five scenarios were run to test different conditions and the influence of scheduling on the energy consumption. Two different sets of production schedules have been evaluated, the first one fulfilling the production requirement in one shift of 10 hours, at high rate, the second one using two 7-hour-long shifts at medium production rate. It was found that the unit cost was minimized in the warmest months of spring and fall, and system shutdown was a crucial factor to reduce energy consumption. A fifth hypothetical scenario was run, with a 4 month continuous production and an 8 month total shutdown, which reduced the energy consumption to a half of the best realistic scenario. When the plant was run in a two-shifts configuration, the cost to coat a vehicle was found to be 29 with weekend shutdown, and 39 without. In the one-shift configuration, the cost was slightly higher, but the difference was less than 5%. While the fifth scenario showed a consistent reduction of the unit cost, inventory and logistic expenses deriving from the

  1. Microstructure and Mechanical Properties of Microwave Post-processed Ni Coating

    NASA Astrophysics Data System (ADS)

    Zafar, Sunny; Sharma, Apurbba Kumar

    2017-03-01

    Flame-sprayed coatings are widely used in the industries attributed to their low cost and simple processing. However, the presence of porosity and poor adhesion with the substrate requires suitable post-processing of the as-sprayed deposits. In the present work, post-processing of the flame-sprayed Ni-based coating has been successfully attempted using microwave hybrid heating. Microwave post-processing of the flame-sprayed coatings was carried out at 2.45 GHz in a 1 kW multimode industrial microwave applicator. The microwave-processed and as-sprayed deposits were characterized for their microstructure, porosity, fracture toughness and surface roughness. The properties of the coatings were correlated with their abrasive wear behavior using a sliding abrasion test on a pin-on-disk tribometer. Microwave post-processing led to healed micropores and microcracks, thus causing homogenization of the microstructure in the coating layer. Therefore, microwave post-processed coating layer exhibits improved mechanical and tribological properties compared to the as-sprayed coating layer.

  2. Microstructure and Mechanical Properties of Microwave Post-processed Ni Coating

    NASA Astrophysics Data System (ADS)

    Zafar, Sunny; Sharma, Apurbba Kumar

    2017-02-01

    Flame-sprayed coatings are widely used in the industries attributed to their low cost and simple processing. However, the presence of porosity and poor adhesion with the substrate requires suitable post-processing of the as-sprayed deposits. In the present work, post-processing of the flame-sprayed Ni-based coating has been successfully attempted using microwave hybrid heating. Microwave post-processing of the flame-sprayed coatings was carried out at 2.45 GHz in a 1 kW multimode industrial microwave applicator. The microwave-processed and as-sprayed deposits were characterized for their microstructure, porosity, fracture toughness and surface roughness. The properties of the coatings were correlated with their abrasive wear behavior using a sliding abrasion test on a pin-on-disk tribometer. Microwave post-processing led to healed micropores and microcracks, thus causing homogenization of the microstructure in the coating layer. Therefore, microwave post-processed coating layer exhibits improved mechanical and tribological properties compared to the as-sprayed coating layer.

  3. PAT-Based Control of Fluid Bed Coating Process Using NIR Spectroscopy to Monitor the Cellulose Coating on Pharmaceutical Pellets.

    PubMed

    Naidu, Venkata Ramana; Deshpande, Rucha S; Syed, Moinuddin R; Deoghare, Piyush; Singh, Dharamvir; Wakte, Pravin S

    2016-12-19

    Current endeavor was aimed towards monitoring percent weight build-up during functional coating process on drug-layered pellets. Near-infrared (NIR) spectroscopy is an emerging process analytical technology (PAT) tool which was employed here within quality by design (QbD) framework. Samples were withdrawn after spraying every 15-Kg cellulosic coating material during Wurster coating process of drug-loaded pellets. NIR spectra of these samples were acquired using cup spinner assembly of Thermoscientific Antaris II, followed by multivariate analysis using partial least squares (PLS) calibration model. PLS model was built by selecting various absorption regions of NIR spectra for Ethyl cellulose, drug and correlating the absorption values with actual percent weight build up determined by HPLC. The spectral regions of 8971.04 to 8250.77 cm(-1), 7515.24 to 7108.33 cm(-1), and 5257.00 to 5098.87 cm(-1) were found to be specific to cellulose, where as the spectral region of 6004.45 to 5844.14 cm(-1)was found to be specific to drug. The final model gave superb correlation co-efficient value of 0.9994 for calibration and 0.9984 for validation with low root mean square of error (RMSE) values of 0.147 for calibration and 0.371 for validation using 6 factors. The developed correlation between the NIR spectra and cellulose content is useful in precise at-line prediction of functional coat value and can be used for monitoring the Wurster coating process.

  4. Thermal interaction between WC-Co coating and steel substrate in process of HVOF spraying

    SciTech Connect

    Guilemany, J.M.; Sobolev, V.V.; Nutting, J.; Dong, Z.; Calero, J.A. . Metalurgia Fisica-Ciencia de Materials)

    1994-10-01

    The WC-Co powders can be used to produce good adhesive and wear resistant HVOF thermal spray coatings on steel and light alloys substrates. In order to understand the properties of this kind of coating, the phases which are present in the coatings and structure changes during post heat treatments have been investigated. Although the coating properties depend very much on the structure developed in the substrate-coating interfacial region it has not been yet investigated in detail. The present study is devoted to the experimental and theoretical analysis of this interfacial region. The structure characterization has been performed mainly through the use of transmission electron microscopy. To provide a theoretical investigation a realistic prediction model of the process has been developed and on its base the mathematical simulation of the substrate-coating thermal interaction has been undertaken.

  5. Photovoltaic characteristics of polymer solar cells fabricated by pre-metered coating process.

    PubMed

    Park, Byoungchoo; Han, Mi-Young

    2009-08-03

    We present the results of a study of flat and uniform poly(3-hexylthiophene):methanofullerene bulk-heterojunction photovoltaic (PV) layers that were produced by a simple pre-metered horizontal-dipping process for the fabrication of polymer solar cells (PSCs). It is shown that this process can produce high quality and thin films by utilizing the downstream meniscus of the solution, which can be controlled by adjusting experimental parameters of the gap height and the carrying speed. It is also shown that the produced PV film exhibits high power conversion efficiency of ca. 4.2% with a large active area. It was demonstrated that this pre-metered process for solution coating may be promising for achieving highly efficient, reliable, and large-area PSCs.

  6. Process, properties, and environmental response of plasma sprayed thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Novak, Richard C.

    1995-01-01

    Experimental results are shown which demonstrate that the properties of plasma sprayed fully stabilized zirconia are strongly influenced by the process parameters. Properties of the coatings in the as-sprayed condition are shown to be additionally influenced by environmental exposure. This behavior is dependent on raw material considerations and processing conditions as well as exposure time and temperature. Process control methodology is described which can take into consideration these complex interactions and help to produce thermal barrier coatings in a cost effective way while meeting coating technical requirements.

  7. Process, properties and environmental response of plasma sprayed thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Novak, R. C.

    1995-01-01

    Experimental results are shown which demonstrate that the properties of plasma sprayed fully stabilized zirconia are strongly influenced by the process parameters. Properties of the coatings in the as-sprayed condition are shown to be additionally influenced by environmental exposure. This behavior is dependent on raw material considerations and processing conditions as well as exposure time and temperature. Process control methodology is described which can take into consideration these complex interactions and help to produce thermal barrier coatings in a cost effective way while meeting coating technical requirements.

  8. Fluorine doping into diamond-like carbon coatings inhibits protein adsorption and platelet activation.

    PubMed

    Hasebe, Terumitsu; Yohena, Satoshi; Kamijo, Aki; Okazaki, Yuko; Hotta, Atsushi; Takahashi, Koki; Suzuki, Tetsuya

    2007-12-15

    The first major event when a medical device comes in contact with blood is the adsorption of plasma proteins. Protein adsorption on the material surface leads to the activation of the blood coagulation cascade and the inflammatory process, which impair the lifetime of the material. Various efforts have been made to minimize protein adsorption and platelet adhesion. Recently, diamond-like carbon (DLC) has received much attention because of their antithrombogenicity. We recently reported that coating silicon substrates with fluorine-doped diamond-like carbon (F-DLC) drastically suppresses platelet adhesion and activation. Here, we evaluated the protein adsorption on the material surfaces and clarified the relationship between protein adsorption and platelet behaviors, using polycarbonate and DLC- or F-DLC-coated polycarbonate. The adsorption of albumin and fibrinogen were assessed using a colorimetric protein assay, and platelet adhesion and activation were examined using a differential interference contrast microscope. A higher ratio of albumin to fibrinogen adsorption was observed on F-DLC than on DLC and polycarbonate films, indicating that the F-DLC film should prevent thrombus formation. Platelet adhesion and activation on the F-DLC films were more strongly suppressed as the amount of fluorine doping was increased. These results show that the F-DLC coating may be useful for blood-contacting devices.

  9. The erosion performance of cold spray deposited metal matrix composite coatings with subsequent friction stir processing

    NASA Astrophysics Data System (ADS)

    Peat, Tom; Galloway, Alexander; Toumpis, Athanasios; McNutt, Philip; Iqbal, Naveed

    2017-02-01

    This study forms an initial investigation into the development of SprayStir, an innovative processing technique for generating erosion resistant surface layers on a chosen substrate material. Tungsten carbide - cobalt chromium, chromium carbide - nickel chromium and aluminium oxide coatings were successfully cold spray deposited on AA5083 grade aluminium. In order to improve the deposition efficiency of the cold spray process, coatings were co-deposited with powdered AA5083 using a twin powder feed system that resulted in thick (>300 μm) composite coatings. The deposited coatings were subsequently friction stir processed to embed the particles in the substrate in order to generate a metal matrix composite (MMC) surface layer. The primary aim of this investigation was to examine the erosion performance of the SprayStirred surfaces and demonstrate the benefits of this novel process as a surface engineering technique. Volumetric analysis of the SprayStirred surfaces highlighted a drop of approx. 40% in the level of material loss when compared with the cold spray deposited coating prior to friction stir processing. Micro-hardness testing revealed that in the case of WC-CoCr reinforced coating, the hardness of the SprayStirred material exhibits an increase of approx. 540% over the unaltered substrate and 120% over the as-deposited composite coating. Microstructural examination demonstrated that the increase in the hardness of the MMC aligns with the improved dispersion of reinforcing particles throughout the aluminium matrix.

  10. Processing and characterization of Ultrathin carbon coatings on glass

    SciTech Connect

    Lee, H.; Rajagopalan, R.; Robinson, J.; Pantano, C.G.

    2009-04-15

    Ultrathin carbon layers, on the order of 3-6 nm in thickness, were formed on glass substrates by spin coating and pyrolysis of polymer precursors. The organic precursors used were poly(furfuryl alcohol), coal tar pitch, and a photoresist. The carbon coatings were characterized by ellipsometry, optical profilometry, water contact angle, confocal Raman spectroscopy, UV-vis spectroscopy, and atomic force microscopy. We also report the transparency, hydrophobicity, friction, weathering resistance, and electrical conductivity of the carbon-coated glass. The results reveal that up to 97% transparent, ultrathin carbon films could be formed on glass substrates with a root-mean-square roughness of less than about to 0.3 nm. This carbon layer modified the otherwise hydrophilic surface of the glass to yield a water contact angle of 85{sup o}. The coatings were also found to provide a water barrier against weathering under hot and humid conditions. A 4.5-nm-thick carbon film on glass had a sheet resistance of 55.6 k {Omega} m and a conductivity of 40 S/cm.

  11. Coated particle waste form development

    SciTech Connect

    Oma, K.H.; Buckwalter, C.Q.; Chick, L.A.

    1981-12-01

    Coated particle waste forms have been developed as part of the multibarrier concept at Pacific Northwest Laboratory under the Alternative Waste Forms Program for the Department of Energy. Primary efforts were to coat simulated nuclear waste glass marbles and ceramic pellets with low-temperature pyrolytic carbon (LT-PyC) coatings via the process of chemical vapor deposition (CVD). Fluidized bed (FB) coaters, screw agitated coaters (SAC), and rotating tube coaters were used. Coating temperatures were reduced by using catalysts and plasma activation. In general, the LT-PyC coatings did not provide the expected high leach resistance as previously measured for carbon alone. The coatings were friable and often spalled off the substrate. A totally different concept, thermal spray coating, was investigated at PNL as an alternative to CVD coating. Flame spray, wire gun, and plasma gun systems were evaluated using glass, ceramic, and metallic coating materials. Metal plasma spray coatings (Al, Sn, Zn, Pb) provided a two to three orders-of-magnitude increase in chemical durability. Because the aluminum coatings were porous, the superior leach resistance must be due to either a chemical interaction or to a pH buffer effect. Because they are complex, coated waste form processes rank low in process feasibility. Of all the possible coated particle processes, plasma sprayed marbles have the best rating. Carbon coating of pellets by CVD ranked ninth when compared with ten other processes. The plasma-spray-coated marble process ranked sixth out of eleven processes.

  12. Interdiffusion behaviors of iron aluminide coatings on China low activation martensitic steel

    NASA Astrophysics Data System (ADS)

    Zhu, X. X.; Yang, H. G.; Yuan, X. M.; Zhao, W. W.; Zhan, Q.

    2014-12-01

    The iron aluminide coating on China Low Activation Martensitic (CLAM) steel was prepared by pack cementation and subsequent heat treatment. A surface Fe2Al5 layer was formed on CLAM substrate by pack cementation process with Fe2Al5 donor powder and NH4Cl activator. Diffusion heat treatment was performed in order to allow the phase transformation from Fe2Al5 to a phase with lower aluminum content. Morphology and composition of the coatings were characterized by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), glow discharge optical emission spectroscopy (GDOES) and X-ray diffraction (XRD). There is a need to study the interdiffusion behaviors in these Al containing systems, as a basis for controlling the formation and subsequent degradation of the coating. In this paper, a predictive model was developed to describe the phase transformation of Fe2Al5 as a function of processing parameters. The Wagner's equation was used to calculate the interdiffusion coefficients based on the analysis of the Al concentration profiles. The results showed that the interdiffusion coefficients in the FeAl and α-Fe(Al) phase strongly depends on Al content and showed a maximum at about 28 at.% Al.

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

    PubMed

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

    2016-01-28

    The formation mechanism of a spray-coated film is different from that of a spin-coated film. This study employs grazing incidence small- and wide-angle X-ray Scattering (GISAXS and GIWAXS, respectively) quantitatively and systematically to investigate the hierarchical structure and phase-separated behavior of a spray-deposited blend film. The formation of PCBM clusters involves mutual interactions with both the P3HT crystal domains and droplet boundary. The processing control and the formed hierarchical structure of the active layer in the spray-coated polymer/fullerene blend film are compared to those in the spin-coated film. How the different post-treatments, such as thermal and solvent vapor annealing, tailor the hierarchical structure of the spray-coated films is quantitatively studied. Finally, the relationship between the processing control and tailored BHJ structures and the performance of polymer solar cell devices is established here, taking into account the evolution of the device area from 1 × 0.3 and 1 × 1 cm(2). The formation and control of the special networks formed by the PCBM cluster and P3HT crystallites, respectively, are related to the droplet boundary. These structures are favorable for the transverse transport of electrons and holes.

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

    PubMed Central

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

    2016-01-01

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

  15. Process evaluation and characterization of TiC coating on graphite for doublet III limiters and neutral beam armor

    NASA Astrophysics Data System (ADS)

    Trester, P. W.; Sevier, D. L.; Chin, J.; Horner, M. H.; Staley, H. G.; Kaplan, R.

    An investigation was conducted to evaluate a thin coating of TiC deposited on a graphite substrate by a commercial CVD coating process. Microstructural analyses are presented for specimens positioned at various locations within the retort during the CVD coating runs. Coating requirements for thickness, quality and uniformity were met. These findings provide the data base for production coating graphite neutral-beam armor and limiter tiles for Tokamaks.

  16. Anti-reflection coatings applied by acid-leaching process. Final report

    SciTech Connect

    Pastirik, E.

    1980-09-01

    The Magicote C process developed by S.M. Thompsen was evaluated for use in applying an antireflective coating to the cover plates of solar cell panels. The process uses a fluosilicic acid solution supersaturated with silica at elevated temperature to selectively attack the surface of soda-lime glass cover plates and alter the physical and chemical composition of a thin layer of glass. The altered glass layer constitutes an antireflective coating. The process produces coatings of excellent optical quality which possess outstanding resistance to soiling and staining. The coatings produced are not resistant to mechanical abrasion and are attacked to some extent by glass cleansers. Control of the filming process was found to be difficult.

  17. Nanohydroxyapatite coating on a titanium-niobium alloy by a hydrothermal process.

    PubMed

    Xiong, Jianyu; Li, Yuncang; Hodgson, Peter D; Wen, Cui'e

    2010-04-01

    A novel one-step hydrothermal coating process was used to produce nanohydroxyapatite (nano-HA) coating on a titanium-niobium (TiNb) alloy substrate in a newly designed solution containing calcium and phosphate ions. The morphology of the coating was studied using scanning electron microscopy. The phase identification of the coating was carried out using X-ray diffraction, attenuated total reflectance Fourier transform infrared spectroscopy and transmission electron microscopy. The reaction between the surface of TiNb alloy and the solution during the hydrothermal process was studied by X-ray photoelectron spectroscopy. Results show that the coating formed on the surface of TiNb alloy was composed of nano-HA particles. During the hydrothermal process, TiO(2) and Nb(2)O(5) formed on the TiNb alloy surface and hydrated to Ti(OH)(4) and Nb(OH)(5), respectively. Calcium phosphate nucleated and grew into a layer of nano-HA particles on the surface of TiNb alloy under the hydrothermal conditions. The crystallinity of the nano-HA coating was improved with the increase in hydrothermal treatment temperature and time duration. Nano-HA coating with good crystallinity was produced on the TiNb alloy via the hydrothermal process at a temperature of 200 degrees C for 12 h.

  18. Anti-Reflective Coating On Borosilicate Long Tubes Industrial Process And Quality Control

    NASA Astrophysics Data System (ADS)

    Eisenberg, N.; Ben-Dor, Y.; Warschawski, J. P.

    1989-07-01

    It has been shown that in order to improve the optical efficiency of a solar trough evacuated pipe used for Luz solar electricity generating systems, an appropriate low cost anti-reflective coating process should be implemented in the solar collector production line, and that a dip process is the optimal choice for this application. It is shown in this paper that pumping the coating solution out of the coating container rather than withdrawing the tubes is the most appropriate coating process for Luz's needs. The same method was employed for the second coating solution which was used both for mechanical abrasion resistance improvement and for increasing optical transmissivity. The measuring procedure for quality insurance of the coated tube was investigated thoroughly and an "in-house" technique, including solar simulation and spiral movement of the tested tube, was chosen in preference to the other standard procedures (spectrophotometry, reflectometry). The complete AR coating facility and production procedure is described and the results of the industrial process are analyzed.

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

    NASA Technical Reports Server (NTRS)

    Himmel, R. P.

    1975-01-01

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

  20. Investigation of passive and active silica-tin oxide nanostructured optical fibers fabricated by "inverse dip-coating" and "powder in tube" method based on the chemical sol-gel process and laser emission

    NASA Astrophysics Data System (ADS)

    Granger, G.; Restoin, C.; Roy, P.; Jamier, R.; Rougier, S.; Duclere, J.-R.; Lecomte, A.; Dauliat, R.; Blondy, J.-M.

    2015-05-01

    This paper presents a study of original nanostructured optical fibers based on the SiO2-SnO2-(Yb3+) system. Two different processes have been developed and compared: the sol-gel chemical method associated to the "inverse dip-coating" (IDC) and the "powder in tube" (PIT). The microstructural and optical properties of the fibers are studied according to the concentration of SnO2. X-Ray Diffraction as well as Transmission Electron Microscopy studies show that the SnO2 crystallizes into the cassiterite phase as nanoparticles with a diameter ranging from 4 to 50 nm as a function of tin oxide concentration. A comparative study highlights a better conservation of SnO2 into the fiber core with the PIT approach according to the refractive index profile and energy dispersive X-Ray spectrometry measurement. The attenuation evaluated by the classic cut-back method gives respectively values higher than 3 dB/m and 0.2 dB/m in the visible (VIS) and infrared (IR) ranges for the PIT fibers whereas background losses reach 0.5 dB/m in the VIS range for IDC fibers. The introduction of ytterbium ions into the core of PIT fibers, directly in the first chemical step, leads to a laser emission (between 1050 and 1100 nm) according to the fiber length under 850 nm wavelength pumping. Luminescence studies have demonstrated the influence of the tin oxide on the rare earth optical properties especially by the modification of the absorption (850 to 1000 nm) and emission (950 to 1100 nm) by discretization of the bands, as well as on the IR emission lifetime evaluated to 10 μs.

  1. Thermal Processing Effects on the Adhesive Strength of PS304 High Temperature Solid Lubricant Coatings

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Edmonds, Brian J.; Benoy, Patricia A.

    2001-01-01

    In this paper the effects of post deposition heat treatments on the cohesive and adhesive strength properties of PS304, a plasma sprayed nickel-chrome based, high temperature solid lubricant coating deposited on stainless steel, are studied. Plasma spray deposited coating samples were exposed in air at temperatures from 432 to 650 C for up to 500 hr to promote residual stress relief, enhance particle to particle bonding and increase coating to substrate bond strength. Coating pull-off strength was measured using a commercial adhesion tester that utilizes 13 mm diameter aluminum pull studs attached to the coating surface with epoxy. Pull off force was automatically recorded and converted to coating pull off strength. As deposited coating samples were also tested as a baseline. The as-deposited (untreated) samples either delaminated at the coating-substrate interface or failed internally (cohesive failure) at about 17 MPa. Samples heat treated at temperatures above 540 C for 100 hr or at 600 C or above for more than 24 hr exhibited strengths above 31 MPa, nearly a two fold increase. Coating failure occurred inside the body of the coating (cohesive failure) for nearly all of the heat-treated samples and only occasionally at the coating substrate interface (adhesive failure). Metallographic analyses of heat-treated coatings indicate that the Nickel-Chromium binder in the PS304 appears to have segregated into two phases, a high nickel matrix phase and a high chromium precipitated phase. Analysis of the precipitates indicates the presence of silicon, a constituent of a flow enhancing additive in the commercial NiCr powder. The exact nature and structure of the precipitate phase is not known. This microstructural change is believed to be partially responsible for the coating strength increase. Diffusion bonding between particles may also be playing a role. Increasing the heat treatment temperature, exposure time or both accelerate the heat treatment process. Preliminary

  2. Effects of shielding coatings on the anode shaping process during counter-rotating electrochemical machining

    NASA Astrophysics Data System (ADS)

    Wang, Dengyong; Zhu, Zengwei; Wang, Ningfeng; Zhu, Di

    2016-09-01

    Electrochemical machining (ECM) has been widely used in the aerospace, automotive, defense and medical industries for its many advantages over traditional machining methods. However, the machining accuracy in ECM is to a great extent limited by the stray corrosion of the unwanted material removal. Many attempts have been made to improve the ECM accuracy, such as the use of a pulse power, passivating electrolytes and auxiliary electrodes. However, they are sometimes insufficient for the reduction of the stray removal and have their limitations in many cases. To solve the stray corrosion problem in CRECM, insulating and conductive coatings are respectively used. The different implement processes of the two kinds of coatings are introduced. The effects of the two kinds of shielding coatings on the anode shaping process are investigated. Numerical simulations and experiments are conducted for the comparison of the two coatings. The simulation and experimental results show that both the two kinds of coatings are valid for the reduction of stray corrosion on the top surface of the convex structure. However, for insulating coating, the convex sidewall becomes concave when the height of the convex structure is over 1.26 mm. In addition, it is easy to peel off by the high-speed electrolyte. In contrast, the conductive coating has a strong adhesion, and can be well reserved during the whole machining process. The convex structure fabricated by using a conductive iron coating layer presents a favorable sidewall profile. It is concluded that the conductive coating is more effective for the improvement of the machining quality in CRECM. The proposed shielding coatings can also be employed to reduce the stray corrosion in other schemes of ECM.

  3. Evaluation of Convergent Spray Technology(TM) Spray Process for Roof Coating Application

    NASA Technical Reports Server (NTRS)

    Scarpa, J.; Creighton, B.; Hall, T.; Hamlin, K.; Howard, T.

    1998-01-01

    The overall goal of this project was to demonstrate the feasibility of(CST) Convergent Spray Technology (Trademark) for the roofing industry. This was accomplished by producing an environmentally compliant coating utilization recycled materials, a CST(Trademark) spray process portable application cart, and hand-held applicator with a CST(Trademark) spray process nozzle. The project culminated with application of this coating to a nine hundred sixty square foot metal for NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama.

  4. Throughput increase by adjustment of the BARC drying time with coat track process

    NASA Astrophysics Data System (ADS)

    Brakensiek, Nickolas L.; Long, Ryan

    2005-05-01

    Throughput of a coater module within the coater track is related to the solvent evaporation rate from the material that is being coated. Evaporation rate is controlled by the spin dynamics of the wafer and airflow dynamics over the wafer. Balancing these effects is the key to achieving very uniform coatings across a flat unpatterned wafer. As today"s coat tracks are being pushed to higher throughputs to match the scanner, the coat module throughput must be increased as well. For chemical manufacturers the evaporation rate of the material depends on the solvent used. One measure of relative evaporation rates is to compare flash points of a solvent. The lower the flash point, the quicker the solvent will evaporate. It is possible to formulate products with these volatile solvents although at a price. Shipping and manufacturing a more flammable product increase chances of fire, thereby increasing insurance premiums. Also, the end user of these chemicals will have to take extra precautions in the fab and in storage of these more flammable chemicals. An alternative coat process is possible which would allow higher throughput in a distinct coat module without sacrificing safety. A tradeoff is required for this process, that being a more complicated coat process and a higher viscosity chemical. The coat process uses the fact that evaporation rate depends on the spin dynamics of the wafer by utilizing a series of spin speeds that first would set the thickness of the material followed by a high spin speed to remove the residual solvent. This new process can yield a throughput of over 150 wafers per hour (wph) given two coat modules. The thickness uniformity of less than 2 nm (3 sigma) is still excellent, while drying times are shorter than 10 seconds to achieve the 150 wph throughput targets.

  5. Understanding the Adsorption Interface of Polyelectrolyte Coating on Redox Active Nanoparticles Using Soft Particle Electrokinetics and Its Biological Activity

    PubMed Central

    2015-01-01

    The application of cerium oxide nanoparticles (CNPs) for therapeutic purposes requires a stable dispersion of nanoparticles in a biological environment. The objective of this study is to tailor the properties of polyelectrolyte coated CNPs as a function of molecular weight to achieve a stable and catalytic active dispersion. The coating of CNPs with polyacrylic acid (PAA) has increased the dispersion stability of CNPs and enhanced the catalytic ability. The stability of PAA coating was analyzed using the change in the Gibbs free energy computed by the Langmuir adsorption model. The adsorption isotherms were determined using soft particle electrokinetics which overcomes the challenges presented by other techniques. The change in Gibbs free energy was highest for CNPs coated with PAA of 250 kg/mol indicating the most stable coating. The change in free energy for PAA of 100 kg/mol coated CNPs was 85% lower than the PAA of 250 kg/mol coated CNPs. This significant difference is caused by the strong adsorption of PAA of 100 kg/mol on CNPs. Catalytic activity of PAA-CNPs is assessed by the catalase enzymatic mimetic activity of nanoparticles. The catalase activity was higher for PAA coated CNPs as compared to bare CNPs which indicated preferential adsorption of hydrogen peroxide induced by coating. This indicates that the catalase activity is also affected by the structure of the coating layer. PMID:24673655

  6. Silver-Coated Nylon Dressing Plus Active DC Microcurrent for Healing of Autogenous Skin Donor Sites

    DTIC Science & Technology

    2013-08-01

    Silver-Coated Nylon Dressing Plus Active DC Microcurrent for Healing of Autogenous Skin Donor Sites Edward W. Malin, MD, Chaya M. Galin, BSN, RN... microcurrent in comparison to silver-coated dressing with sham microcurrent on wound-closure time for autogenous skin donor sites. Methods: Four...hundred five patients were screened for treatment of their donor sites using a silver-coated nylon dressing with either sham or active microcurrent

  7. Antibacterial Activity of Polymer Coated Cerium Oxide Nanoparticles

    PubMed Central

    Shah, Vishal; Shah, Shreya; Shah, Hirsh; Rispoli, Fred J.; McDonnell, Kevin T.; Workeneh, Selam; Karakoti, Ajay; Kumar, Amit; Seal, Sudipta

    2012-01-01

    Cerium oxide nanoparticles have found numerous applications in the biomedical industry due to their strong antioxidant properties. In the current study, we report the influence of nine different physical and chemical parameters: pH, aeration and, concentrations of MgSO4, CaCl2, KCl, natural organic matter, fructose, nanoparticles and Escherichia coli, on the antibacterial activity of dextran coated cerium oxide nanoparticles. A least-squares quadratic regression model was developed to understand the collective influence of the tested parameters on the anti-bacterial activity and subsequently a computer-based, interactive visualization tool was developed. The visualization allows us to elucidate the effect of each of the parameters in combination with other parameters, on the antibacterial activity of nanoparticles. The results indicate that the toxicity of CeO2 NPs depend on the physical and chemical environment; and in a majority of the possible combinations of the nine parameters, non-lethal to the bacteria. In fact, the cerium oxide nanoparticles can decrease the anti-bacterial activity exerted by magnesium and potassium salts. PMID:23110109

  8. The Insulation of Copper Wire by the Electrostatic Coating Process.

    DTIC Science & Technology

    1983-06-30

    Propvlene) FEP is based on duPont’s Teflon ’ FEP . It has the best electrical, chemical, friction and release properties of all Liquinite coatings...ETFE (ethylene-tetrafluoroethylene copolymer), PFA (perfluoroalkoxy resin), ECTFE (ethylene-chlorotrifluoroethylene), and FEP (fluorinated ethylene...cure. PPS/ PTFE Grades of PPS modified with PTFE are available for improved friction, wear and release properties and physical and temperature

  9. Development of Protective Coatings for Co-Sequestration Processes and Pipelines

    SciTech Connect

    Bierwagen, Gordon; Huang, Yaping

    2011-11-30

    The program, entitled Development of Protective Coatings for Co-Sequestration Processes and Pipelines, examined the sensitivity of existing coating systems to supercritical carbon dioxide (SCCO2) exposure and developed new coating system to protect pipelines from their corrosion under SCCO2 exposure. A literature review was also conducted regarding pipeline corrosion sensors to monitor pipes used in handling co-sequestration fluids. Research was to ensure safety and reliability for a pipeline involving transport of SCCO2 from the power plant to the sequestration site to mitigate the greenhouse gas effect. Results showed that one commercial coating and one designed formulation can both be supplied as potential candidates for internal pipeline coating to transport SCCO2.

  10. Fabrication of Nanosized Lanthanum Zirconate Powder and Deposition of Thermal Barrier Coating by Plasma Spray Process

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Jagdeesh, N.; Pathak, L. C.

    2016-07-01

    The present manuscript discusses our findings on fabrication of nanosized lanthanum zirconate powder for thermal barrier coating application and its coating by plasma spray on nickel-based superalloy substrate. Single-phase La2Zr2O7 coating of thickness of the order of 45 µm on the Ni-Cr-Al bond coat coated Ni-based superalloy substrate was deposited by plasma spray process. The layers at the interface did not show spallation and inter diffusion was very less. The microstructure, interface, porosity, and mechanical properties of different layers are investigated. The lanthanum zirconate hardness and modulus were 10.5 and 277 GPa, respectively. The load depth curve for lanthanum zirconate showed good elastic recovery around 74%.

  11. Method and Process Development of Advanced Atmospheric Plasma Spraying for Thermal Barrier Coatings

    NASA Astrophysics Data System (ADS)

    Mihm, Sebastian; Duda, Thomas; Gruner, Heiko; Thomas, Georg; Dzur, Birger

    2012-06-01

    Over the last few years, global economic growth has triggered a dramatic increase in the demand for resources, resulting in steady rise in prices for energy and raw materials. In the gas turbine manufacturing sector, process optimizations of cost-intensive production steps involve a heightened potential of savings and form the basis for securing future competitive advantages in the market. In this context, the atmospheric plasma spraying (APS) process for thermal barrier coatings (TBC) has been optimized. A constraint for the optimization of the APS coating process is the use of the existing coating equipment. Furthermore, the current coating quality and characteristics must not change so as to avoid new qualification and testing. Using experience in APS and empirically gained data, the process optimization plan included the variation of e.g. the plasma gas composition and flow-rate, the electrical power, the arrangement and angle of the powder injectors in relation to the plasma jet, the grain size distribution of the spray powder and the plasma torch movement procedures such as spray distance, offset and iteration. In particular, plasma properties (enthalpy, velocity and temperature), powder injection conditions (injection point, injection speed, grain size and distribution) and the coating lamination (coating pattern and spraying distance) are examined. The optimized process and resulting coating were compared to the current situation using several diagnostic methods. The improved process significantly reduces costs and achieves the requirement of comparable coating quality. Furthermore, a contribution was made towards better comprehension of the APS of ceramics and the definition of a better method for future process developments.

  12. Accumulated damage process of thermal sprayed coating under rolling contact by acoustic emission technique

    NASA Astrophysics Data System (ADS)

    Xu, Jia; Zhou, Zhen-yu; Piao, Zhong-yu

    2016-09-01

    The accumulated damage process of rolling contact fatigue (RCF) of plasma-sprayed coatings was investigated. The influences of surface roughness, loading condition, and stress cycle frequency on the accumulated damage status of the coatings were discussed. A ball-ondisc machine was employed to conduct RCF experiments. Acoustic emission (AE) technique was introduced to monitor the RCF process of the coatings. AE signal characteristics were investigated to reveal the accumulated damage process. Result showed that the polished coating would resist the asperity contact and remit accumulated damage. The RCF lifetime would then extend. Heavy load would aggravate the accumulated damage status and induce surface fracture. Wear became the main failure mode that reduced the RCF lifetime. Frequent stress cycle would aggravate the accumulated damage status and induce interface fracture. Fatigue then became the main failure mode that also reduced the RCF lifetime.

  13. Structural formation and photocatalytic activity of magnetron sputtered titania and doped-titania coatings.

    PubMed

    Kelly, Peter J; West, Glen T; Ratova, Marina; Fisher, Leanne; Ostovarpour, Soheyla; Verran, Joanna

    2014-10-13

    Titania and doped-titania coatings can be deposited by a wide range of techniques; this paper will concentrate on magnetron sputtering techniques, including "conventional" reactive co-sputtering from multiple metal targets and the recently introduced high power impulse magnetron sputtering (HiPIMS). The latter has been shown to deliver a relatively low thermal flux to the substrate, whilst still allowing the direct deposition of crystalline titania coatings and, therefore, offers the potential to deposit photocatalytically active titania coatings directly onto thermally sensitive substrates. The deposition of coatings via these techniques will be discussed, as will the characterisation of the coatings by XRD, SEM, EDX, optical spectroscopy, etc. The assessment of photocatalytic activity and photoactivity through the decomposition of an organic dye (methylene blue), the inactivation of E. coli microorganisms and the measurement of water contact angles will be described. The impact of different deposition technologies, doping and co-doping strategies on coating structure and activity will be also considered.

  14. A Silicon-Based, Sequential Coat-and-Etch Process to Fabricate Nearly Perfect Substrate Surfaces

    SciTech Connect

    Mirkarimi, P B; Spiller, E; Baker, S L; Stearns, D G; Robinson, J C; Olynick, D L; Salmassi, F; Liddle, J A; Liang, T; Stivers, A R

    2005-07-05

    For many thin-film applications substrate imperfections such as particles, pits, scratches, and general roughness, can nucleate film defects which can severely detract from the coating's performance. Previously we developed a coat-and-etch process, termed the ion beam thin film planarization process, to planarize substrate particles up to {approx} 70 nm in diameter. The process relied on normal incidence etching; however, such a process induces defects nucleated by substrate pits to grow much larger. We have since developed a coat-and-etch process to planarize {approx}70 nm deep by 70 nm wide substrate pits; it relies on etching at an off-normal incidence angle, i.e., an angle of {approx} 70{sup o} from the substrate normal. However, a disadvantage of this pit smoothing process is that it induces defects nucleated by substrate particles to grow larger. Combining elements from both processes we have been able to develop a silicon-based, coat-and-etch process to successfully planarize {approx}70 nm substrate particles and pits simultaneously to at or below 1 nm in height; this value is important for applications such as extreme ultraviolet lithography (EUVL) masks. The coat-and-etch process has an added ability to significantly reduce high-spatial frequency roughness, rendering a nearly perfect substrate surface.

  15. Robust superhydrophobic transparent coatings fabricated by a low-temperature sol-gel process

    NASA Astrophysics Data System (ADS)

    Huang, Wei-Heng; Lin, Chao-Sung

    2014-06-01

    A coating with robust, superhydrophobic, and transparent properties was fabricated on glass substrates by a sol-gel method at a temperature of 80 °C. The coating was formed in a solution containing silica nanoparticles and silicic acid, in which the ratio of silica nanoparticles and silicic acid was varied to tune the roughness of the coating. Subsequently, the as-deposited coating was dipped with a low surface energy material, 1H,1H,2H,2H-perfluorooctyltrichloro silane. The coated glass substrate was characterized in terms of surface morphology, optical transmittance, water- and CH2I2-contact angles, and its chemical as well as mechanical stability was evaluated by ultrasonication in ethanol for 120 min. The results showed that the coating had a water contact angle exceeding 160°, a sliding angle lower than 10°, a CH2I2 static contact angle of approximately 150°. The transmittance of the coating was reduced by less than 5% compared to that of the bare glass substrate at wavelengths above 500 nm. Moreover, the properties of the coating hardly changed after the ultrasonication test and still retained the superhydrophobicity after water dropping impact. Because the fabrication process is performed under low temperatures, it is feasible for scale-up production at low energy consumptions.

  16. Comparison of different hard, metal-like coatings sprayed by plasma and detonation gun processes

    SciTech Connect

    Vuoristo, P.; Niemi, K.; Maentylae, T.; Berger, L.M.; Nebelung, M.

    1995-12-31

    Structure and wear properties of atmospheric plasma sprayed and detonation gun sprayed coatings prepared from an experimental (Ti,Mo)C-28.4%NiCo powder were compared to coatings sprayed from commercially available WC-12%Co and Cr{sub 3}C{sub 2}-25%NiCr powders. All powders had an agglomerated (spray dried) and sintered structure and nearly the same content of the metallic binder of approximately 20 vol.-%. The powders were characterized by SEM (morphology and cross-sections) and X-ray diffraction (phase composition). The coatings were studied by optical microscope, microhardness measurements, X-ray diffraction analysis and by abrasion and erosion wear tests. The X-ray diffraction patterns of the coatings show that the (Ti,Mo)C-28.4%NiCo powder is characterized by high phase stability in both spray processes, whereas the WC-12%Co powder is prone to significant phase transformations during spraying. The results clearly show the high potential of the experimental (Ti,Mo)C-28.4%NiCo coatings in substituting the conventional systems in wear applications. For instance, it was found that plasma spraying of the (Ti,Mo)C-28.4%NiCo powder with an Ar-H{sub 2} plasma gas resulted in coatings with wear resistance comparable to WC-12%Co coatings. However, detonation gun sprayed WC-12%Co coatings showed somewhat better abrasion wear resistance.

  17. Plasma sprayed manganese-cobalt spinel coatings: Process sensitivity on phase, electrical and protective performance

    NASA Astrophysics Data System (ADS)

    Han, Su Jung; Pala, Zdenek; Sampath, Sanjay

    2016-02-01

    Manganese cobalt spinel (Mn1.5Co1.5O4, MCO) coatings are prepared by the air plasma spray (APS) process to examine their efficacy in serving as protective coatings from Cr-poisoning of the cathode side in intermediate temperature-solid oxide fuel cells (IT-SOFCs). These complex oxides are susceptible to process induced stoichiometric and phase changes which affect their functional performance. To critically examine these effects, MCO coatings are produced with deliberate modifications to the spray process parameters to explore relationship among process conditions, microstructure and functional properties. The resultant interplay among particle thermal and kinetic energies are captured through process maps, which serve to characterize the parametric effects on properties. The results show significant changes to the chemistry and phase composition of the deposited material resulting from preferential evaporation of oxygen. Post deposition annealing recovers oxygen in the coatings and allows partial recovery of the spinel phase, which is confirmed through thermo-gravimetric analysis (TGA)/differential scanning calorimetry (DSC), X-ray Diffraction (XRD), and magnetic hysteresis measurements. In addition, coatings with high density after sintering show excellent electrical conductivity of 40 S cm-1 at 800 °C while simultaneously providing requisite protection characteristics against Cr-poisoning. This study provides a framework for optimal evaluation of MCO coatings in intermediate temperature SOFCs.

  18. Pt monolayer coating on complex network substrate with high catalytic activity for the hydrogen evolution reaction

    PubMed Central

    Li, Man; Ma, Qiang; Zi, Wei; Liu, Xiaojing; Zhu, Xuejie; Liu, Shengzhong (Frank)

    2015-01-01

    A deposition process has been developed to fabricate a complete-monolayer Pt coating on a large-surface-area three-dimensional (3D) Ni foam substrate using a buffer layer (Ag or Au) strategy. The quartz crystal microbalance, current density analysis, cyclic voltammetry integration, and X-ray photoelectron spectroscopy results show that the monolayer deposition process accomplishes full coverage on the substrate and the deposition can be controlled to a single atomic layer thickness. To our knowledge, this is the first report on a complete-monolayer Pt coating on a 3D bulk substrate with complex fine structures; all prior literature reported on submonolayer or incomplete-monolayer coating. A thin underlayer of Ag or Au is found to be necessary to cover a very reactive Ni substrate to ensure complete-monolayer Pt coverage; otherwise, only an incomplete monolayer is formed. Moreover, the Pt monolayer is found to work as well as a thick Pt film for catalytic reactions. This development may pave a way to fabricating a high-activity Pt catalyst with minimal Pt usage. PMID:26601247

  19. In vitro evaluation of the antibacterial and osteogenic activity promoted by selenium-doped calcium phosphate coatings.

    PubMed

    Rodríguez-Valencia, C; Freixeiro, P; Serra, J; Ferreirós, C M; González, P; López-Álvarez, M

    2017-02-24

    Selenium is an essential trace element present in 25 selenoenzymes, playing critical roles in a variety of physiological processes, such as anti-oxidative defense and the modulation of cell proliferation and differentiation. This paper characterizes selenium-doped calcium phosphate coatings and evaluates their effects on the osteogenic activity, the proliferation of osteosarcoma cells and biofilm formation. To do so, the structure and elemental composition of the obtained coatings were analyzed, in addition to their thicknesses, and they were compared to pure calcium phosphate coatings. Moreover, the dose-effect ratio of two coatings with the lower (0.6 at%) and the higher (2.7 at%) selenium content was studied in terms of osteogenic, anti-biofilm and cancerous anti-proliferative properties. The results showed the incorporation of selenium in the form of selenite groups into the hydroxyapatite structure, with a similar crystalline pattern to the latter and increased roughness of the coatings. The calcium phosphate coatings with 2.7 at% of selenium resulted in significant osteogenic activity (p < 0.01) of healthy pre-osteoblasts (MC3T3-E1) over long periods of incubation, a significant anti-proliferative effect (p < 0.01) on cancerous osteoblasts (MG63) in a preliminary study, and anti-biofilm properties (p < 0.01) against Staphylococcus epidermidis and Staphylococcus aureus bacterial strains, which are responsible for most infections after orthopedic surgeries.

  20. Optically and biologically active mussel protein-coated double-walled carbon nanotubes.

    PubMed

    Jung, Yong Chae; Muramatsu, Hiroyuki; Fujisawa, Kazunori; Kim, Jin Hee; Hayashi, Takuya; Kim, Yoong Ahm; Endo, Morinobu; Terrones, Mauricio; Dresselhaus, Mildred S

    2011-12-02

    A method of dispersing strongly bundled double-walled carbon nanotubes (DWNTs) via a homogeneous coating of mussel protein in an aqueous solution is presented. Optical activity, mechanical strength, as well as electrical conductivity coming from the nanotubes and the versatile biological activity from the mussel protein make mussel-coated DWNTs promising as a multifunctional scaffold and for anti-fouling materials.

  1. Immobilization of Hg(II) in water with polysulfide-rubber (PSR) polymer-coated activated carbon.

    PubMed

    Kim, Eun-Ah; Seyfferth, Angelia L; Fendorf, Scott; Luthy, Richard G

    2011-01-01

    An effective mercury removal method using polymer-coated activated carbon was studied for possible use in water treatment. In order to increase the affinity of activated carbon for mercury, a sulfur-rich compound, polysulfide-rubber (PSR) polymer, was effectively coated onto the activated carbon. The polymer was synthesized by condensation polymerization between sodium tetrasulfide and 1,2-dichloroethane in water. PSR-mercury interactions and Hg-S bonding were elucidated from x-ray photoelectron spectroscopy, and Fourier transform infra-red spectroscopy analyses. The sulfur loading levels were controlled by the polymer dose during the coating process and the total surface area of the activated carbon was maintained for the sulfur loading less than 2 wt%. Sorption kinetic studies showed that PSR-coated activated carbon facilitates fast reaction by providing a greater reactive surface area than PSR alone. High sulfur loading on activated carbon enhanced mercury adsorption contributing to a three orders of magnitude reduction in mercury concentration. μ-X-ray absorption near edge spectroscopic analyses of the mercury bound to activated carbon and to PSR on activated carbon suggests the chemical bond with mercury on the surface is a combination of Hg-Cl and Hg-S interaction. The pH effect on mercury removal and adsorption isotherm results indicate competition between protons and mercury for binding to sulfur at low pH.

  2. PROCESS OF COATING METALS WITH BISMUTH OR BISMUTH-BASE ALLOYS

    DOEpatents

    Beach, J.G.

    1958-01-28

    A method is described for producing coatings of bismuth or bismuth alloys on a metal base. This is accomplished by electrodepositing the bismuth from an aqueous solution of BiCl/sub 3/, and by making the metal base alternately the cathode and the anode, the cathode periods being twice as long as the anode periods. In one embodiment a nickel coating is first electrodeposited in a known way, and this nickel plated piece is tae base upon which tae bismuth is deposited by the process of this patent. The coated piece is then heat treated to produce a homogeneous Ni--Bi alloy by diffusion.

  3. Influence of the aqueous film coating process on the properties and stability of tablets containing a moisture-labile drug.

    PubMed

    Ruotsalainen, Mirja; Heinämäki, Jyrki; Taipale, Krista; Yliruusi, Jouko

    2003-01-01

    The effects of an aqueous film coating process on the morphology and storage stability of hydroxypropyl methylcellulose-coated tablets containing a moisture-labile model drug (acetylsalicylic acid, ASA) were evaluated using an instrumented side-vented tablet pan coater. Coating parameters studied were inlet air absolute humidity 5 g/m3 and 12 g/m3, spraying air pressure 100 kPa and 500 kPa, pan air temperature 35 degrees C and 55 degrees C, and coating solution flow rate 2.2 g/min and 7.8 g/min. The surface roughness of the coatings was measured with a laser profilometer and the chemical hydrolysis of the model drug ASA with an UV-spectrophotometer. The film-coated tablets were stored at 25 degrees C/60% RH and 40 degrees C/75% RH for three months. The high absolute humidity of the inlet air increased the residual water content and surface roughness of the coated tablets. Using a lower coating solution flow rate, higher spraying air pressure and pan temperature the coatings were smooth and homogeneous. In both ambient and accelerated storage conditions, the roughness of the coatings and the hydrolysis of ASA increased, but this was independent of the film coating process. Uniform and smooth hydroxypropyl methylcellulose coatings can be achieved by improved control of process parameters related to the application of the coating solution and water evaporation of the tablet surface.

  4. Reflection, transmission and color measurement system for the online quality control of float glass coating process

    NASA Astrophysics Data System (ADS)

    Mamedbeili, Izmir; Cakiroglu, Fahrettin; Bektas, Gokhan; Riza, Dadash; Hacizade, Fikret

    2013-04-01

    Over the past century there has been a dramatic increase in the demand for float glass in many fields of industry. Usually, 10 to 30% of produced float glass is coated with various coatings for different purposes. As a consequence quality control of the coatings is one of the most current issues during the process of float glass manufacturing. In this work we describe a system designed for the online control of reflectivity, transmittance and color coordinates of the coatings during the glass production process. The working principle of the system is based on the measurement of the spectral characteristics of reflectivity and transmittance of coatings within the 400-700 nm spectrophotometer spectral range during the online coating process. The measurement unit consists of two microspectrometers (one for the measurements of the spectral characteristics of the reference source, and the other for the measurements of the reflectance spectrum), illumination head (consisting of one white 1W LED and collimating lenses), stabilized power supply, microprocessor and 18 bits precision ADC. The use of the reference channel allows us to stabilize the intensity of the incident light up to 10-4 level. The repeatability of the measurement of reflectivity coefficient in laboratory conditions was in range of +/- 0.001. However, in the measurements in the factory environment, due to the vibration of the glass ribbon on the conveyer, the measurement reproducibility was about +/- 0.005.

  5. Laser Processing of Fe-Based Bulk Amorphous Alloy Coatings on Titanium

    NASA Astrophysics Data System (ADS)

    Sahasrabudhe, Himanshu; Dittrick, Stanley A.; Bandyopadhyay, Amit

    2013-11-01

    Laser Engineered Net Shaping (LENS™), a solid freeform fabrication technique, was employed for the processing of Fe-based bulk amorphous alloy (Fe BAA) powder on titanium. One and two layers of the Fe BAA were deposited with the same processing parameters. SEM and XRD analyses of the Fe BAA coatings revealed the retention of the feedstock powder's amorphous nature. The mixing of the feedstock powder in the titanium substrate was very small. A crystalline-amorphous composite microstructure evolved from the laser processing in all types of coatings. The coatings were further laser remelted. The amorphous character was found to increase and the crystallites were found to grow during remelting. The Fe BAA coatings showed higher hardness and smaller wear volume compared to the Ti substrate. A further increase in these properties was observed after laser remelting treatment. During the wear testing in NaCl solution, Ti substrate showed intergranular corrosion, whereas the Fe BAA coatings showed signs of low and localized fretting corrosion in a saline environment. Our results demonstrate that using LENS™, amorphous coatings can be deposited on metallic substrates.

  6. In situ imaging and height reconstruction of phase separation processes in polymer blends during spin coating.

    PubMed

    Ebbens, Stephen; Hodgkinson, Richard; Parnell, Andrew J; Dunbar, Alan; Martin, Simon J; Topham, Paul D; Clarke, Nigel; Howse, Jonathan R

    2011-06-28

    Spin coating polymer blend thin films provides a method to produce multiphase functional layers of high uniformity covering large surface areas. Applications for such layers include photovoltaics and light-emitting diodes where performance relies upon the nanoscale phase separation morphology of the spun film. Furthermore, at micrometer scales, phase separation provides a route to produce self-organized structures for templating applications. Understanding the factors that determine the final phase-separated morphology in these systems is consequently an important goal. However, it has to date proved problematic to fully test theoretical models for phase separation during spin coating, due to the high spin speeds, which has limited the spatial resolution of experimental data obtained during the coating process. Without this fundamental understanding, production of optimized micro- and nanoscale structures is hampered. Here, we have employed synchronized stroboscopic illumination together with the high light gathering sensitivity of an electron-multiplying charge-coupled device camera to optically observe structure evolution in such blends during spin coating. Furthermore the use of monochromatic illumination has allowed interference reconstruction of three-dimensional topographies of the spin-coated film as it dries and phase separates with nanometer precision. We have used this new method to directly observe the phase separation process during spinning for a polymer blend (PS-PI) for the first time, providing new insights into the spin-coating process and opening up a route to understand and control phase separation structures.

  7. Zinc-sulphate-heptahydrate coated activated carbon for microbe removal from stormwater.

    PubMed

    Guest, R M; Schang, C; Deletic, A; McCarthy, D T

    2012-01-01

    There is a need to develop effective stormwater filters for passive (without any addition of chemicals or energy) and effective removal of pathogens in order to mainstream stormwater harvesting. This study focuses on the development of coated granular activated carbon (GAC) filtration material in order to develop filters for effective removal of pathogens from urban stormwater. Several laboratory trials were performed to gauge the effectiveness of the filters, which use a mixture of the zinc-sulphate-heptahydrate coated GAC and sand, on the removal of Escherichia coli (E. coli) from semi-natural stormwater. On average, a 98% removal of the inflow concentration of E. coli was achieved. Furthermore, there was also an improvement of approximately 25% in the removal of phosphorous. However, it was found that the treated material was leaching zinc. It was important to determine whether the observed removal of E. coli was indirectly caused by the sampling methodology. The results showed that the inactivation of the E. coli in the collected sample was small compared with the inactivation which actually occurred within the filter. This provides much promise to the filter, but the presence of zinc in the outflow demonstrates the need for further investigation into the stabilisation of the coating process.

  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. Warm spraying—a novel coating process based on high-velocity impact of solid particles

    PubMed Central

    Kuroda, Seiji; Kawakita, Jin; Watanabe, Makoto; Katanoda, Hiroshi

    2008-01-01

    In recent years, coating processes based on the impact of high-velocity solid particles such as cold spraying and aerosol deposition have been developed and attracting much industrial attention. A novel coating process called ‘warm spraying’ has been developed, in which coatings are formed by the high-velocity impact of solid powder particles heated to appropriate temperatures below the melting point of the powder material. The advantages of such process are as follows: (1) the critical velocity needed to form a coating can be significantly lowered by heating, (2) the degradation of feedstock powder such as oxidation can be significantly controlled compared with conventional thermal spraying where powder is molten, and (3) various coating structures can be realized from porous to dense ones by controlling the temperature and velocity of the particles. The principles and characteristics of this new process are discussed in light of other existing spray processes such as high-velocity oxy-fuel spraying and cold spraying. The gas dynamics of particle heating and acceleration by the spraying apparatus as well as the high-velocity impact phenomena of powder particles are discussed in detail. Several examples of depositing heat sensitive materials such as titanium, metallic glass, WC–Co cermet and polymers are described with potential industrial applications. PMID:27877996

  10. Preservation of H 2 production activity in nanoporous latex coatings of Rhodopseudomonas palustris CGA009 during dry storage at ambient temperatures: Preservation of R.palustris latex coatings

    DOE PAGES

    Piskorska, M.; Soule, T.; Gosse, J. L.; ...

    2013-07-21

    To assess the applicability of latex cell coatings as an ‘off-the-shelf’ biocatalyst, the effect of osmoprotectants, temperature, humidity and O2 on preservation of H2 production in Rhodopseudomonas palustris coatings was evaluated. Immediately following latex coating coalescence (24 h) and for up to 2 weeks of dry storage, rehydrated coatings containing different osmoprotectants displayed similar rates of H2 production. Beyond 2 weeks of storage, sorbitol-treated coatings lost all H2 production activity, whereas considerable H2 production was still detected in sucrose- and trehalose-stabilized coatings. We stored the coatings at a relative humidity level which significantly impacts the recovery and subsequent rates ofmore » H2 production. After 4 weeks storage under air at 60% humidity, coatings produced only trace amounts of H2 (0–0.1% headspace accumulation), whereas those stored at < 5% humidity retained 27–53% of their H2 production activity after 8 weeks of storage. Furthermore, when stored in argon at < 5% humidity and room temperature, R. palustris coatings retained full H2 production activity for 3 months, implicating oxidative damage as a key factor limiting coating storage. Ultimately, the results demonstrate that biocatalytic latex coatings are an attractive cell immobilization platform for preservation of bioactivity in the dry state.« less

  11. Effects of HVOF Process Parameters on the Properties of Ni-Cr Coatings

    NASA Astrophysics Data System (ADS)

    Saaedi, J.; Coyle, T. W.; Arabi, H.; Mirdamadi, S.; Mostaghimi, J.

    2010-03-01

    This research examined the influence of processing parameters on the structure of a Ni-50Cr coating applied by high-velocity oxy-fuel spraying onto stainless steel specimens. This type of coating is normally used as protection against heat and corrosion encountered in power plant and marine boilers, and oil refinery heaters. A statistical design of experiments identified fuel and oxygen flow rates and spraying distance as the most influential parameters controlling the in-flight characteristics of the powder particles prior to impact. The effects of these parameters on the porosity level, oxide content, and microhardness of the coatings were then investigated in more detail. These results indicated that the oxide content and hardness of the coatings were dependent on the gas combustion ratio but not on spraying distance. The porosity level and amount of unmelted particles were reduced at the longest spraying distance.

  12. Study of Rb-vapor coated cells — Atomic diffusion and cell curing process

    NASA Astrophysics Data System (ADS)

    Atutov, S. N.; Benimetskiy, F. A.; Plekhanov, A. I.; Sorokin, V. A.

    2016-02-01

    We present the results of a study on an optical-resonant cell filled by a vapor of the Rb atoms and coated with a non-stick polydimethylsiloxane (PDMS) polymer. We show that it is possible to define correctly the diffusion coefficient of the atoms in the coating using the geometric parameters of the cell and the vapor density in the cell volume only. The dependence of the diffusion coefficient on the cell curing time is presented. It is shown that the mysterious cell curing process can be explained in terms of the polymerization of the polymer coating by alkali atoms. The anomalous long dwell time of the Rb atoms on the PDMS coating is discussed as well.

  13. Activation and fluoride-assisted phosphating of aluminum-silicon-coated steel.

    PubMed

    Schneider, Paul; Sigel, Reinhard; Lange, Miriam M; Beier, Frank; Renner, Frank U; Erbe, Andreas

    2013-05-22

    Phosphating is a crucial process in the corrosion protection of metals. Here, activation and fluoride-assisted tricationic phosphating is investigated on aluminum-silicon (AS) coated steel surfaces. Dynamic light scattering results from the activation bath show a bimodal size distribution, with hydrodynamic radii of ~400 nm and ~10 μm. For the smaller particle fraction, static light scattering results are consistent with the interpretation of disklike particles as scattering objects. Particles of the larger fraction sediment with time. In the presence of electrolyte, the scattering intensity from the larger particle fraction increases. Coagulation with time is suggested to be related to the decrease in activity of the activation bath. Scanning Auger microscopy (SAM) shows a higher phosphorus concentration after titanium phosphate activation in the Al-rich areas compared to the Si-rich areas of the AS coatings. There is no correlation between the size of the species in the activation bath, and the size of the phosphate-containing regions on the activated surface. Phosphating was performed in the presence of hexafluorosilicic acid, H2SiF6, ammonium hydrogen difluoride, NH4HF2, and both, at an initial pH of 2.5. The absence of crystals after phosphating with H2SiF6 is an indication that SiF6(2-) is the final product of the oxide dissolution in the presence of fluoride. In the presence of NH4HF2, the Si-rich regions of the surface are phosphated before the Si-poor (Al-rich) regions. Hence, the phosphate distribution after activation and after phosphating are opposite. These results show that a high surface concentration of phosphate after activation is not sufficient for a high coverage with phosphate crystals after phosphating.

  14. Adsorption of doxorubicin on poly(methyl methacrylate)-chitosan-heparin-coated activated carbon beads.

    PubMed

    Miao, Jianjun; Zhang, Fuming; Takieddin, Majde; Mousa, Shaker; Linhardt, Robert J

    2012-03-06

    Extracorporeal filter cartridges, filled with an activated carbon bead (ACB) adsorbent, have been used for removal of overdosed cancer drugs from the blood. Coatings on adsorbent matrices, poly(methyl methacrylate) (PMMA)/activated carbon bead and PMMA/chitosan/heparin/ACB composites, were tested to improve their biocompatibility and blood compatibility. PMMA coating on ACBs was accomplished in a straightforward manner using a PMMA solution in ethyl acetate. A one-step hybrid coating of ACBs with PMMA-anticoagulant heparin required the use of acetone and water co-solvents. Multilayer coatings with three components, PMMA, chitosan, and heparin, involved three steps: PMMA was first coated on ACBs; chitosan was then coated on the PMMA-coated surface; and finally, heparin was covalently attached to the chitosan coating. Surface morphologies were studied by scanning electron microscopy. X-ray photoelectron spectroscopy confirmed the -SO(3)(-) group. Adsorption, of a chemotherapy drug (doxorubicin) from both water and phosphate-buffered saline, by the coated ACBs was examined. The adsorption isotherm curves were fitted using the Freundlich model. The current adsorption system might find potential applications in the removal of high-dose regional chemotherapy drugs while maintaining high efficiency, biocompatibility, and blood compatibility.

  15. Process for ultra smooth diamond coating on metals and uses thereof

    NASA Technical Reports Server (NTRS)

    Vohra, Yogesh K. (Inventor); Catledge, Shane A. (Inventor)

    2001-01-01

    The present invention provides a new process to deposit well adhered ultra smooth diamond films on metals by adding nitrogen gas to the methane/hydrogen plasma created by a microwave discharge. Such diamond coating process is useful in tribological/wear resistant applications in bio-implants, machine tools, and magnetic recording industry.

  16. Physical processes and modeling of plasma deposition and hardening of coatings-switched electrical parameters

    NASA Astrophysics Data System (ADS)

    Kadyrmetov, A. M.; Sharifullin, S. N.

    2016-11-01

    This paper presents the results of simulation of plasma deposition and hardening of coatings in modulating the electrical parameters. Mathematical models are based on physical models of gas-dynamic mechanisms more dynamic and thermal processes of the plasma jet. As an example the modeling of dynamic processes of heterogeneous plasma jet, modulated current pulses indirect arc plasma torch.

  17. Laser Processed TiN Reinforced Ti6Al4V Composite Coatings

    PubMed Central

    Balla, Vamsi Krishna; Bhat, Abhimanyu; Bose, Susmita; Bandyopadhyay, Amit

    2011-01-01

    The purpose of this first generation investigation is to evaluate fabrication, in vitro cytotoxicity, cell-materials interactions and tribological performance of TiN particle reinforced Ti6Al4V composite coatings for potential wear resistant load bearing implant applications. The microstructural analysis of the composites was performed using scanning electron microscope and phase analysis was done with X-ray diffraction. In vitro cell-materials interactions, using human fetal osteoblast cell line, have been assessed on these composite coatings and compared with Ti6Al4V alloy control samples. The tribological performance of the coatings were evaluated, in simulated body fluids, up to 1000 m sliding distance under 10N normal load. The results show that the composite coatings contain distinct TiN particles embedded in α + β phase matrix. The average top surface hardness of Ti6Al4V alloy increased from 394 ± 8 HV to 1138 ± 61 HV with 40 wt.% TiN reinforcement. Among the composite coatings, the coatings reinforced with 40 wt. % TiN exhibited the highest wear resistance of 3.74 × 10-6 mm3/Nm, which is lower than the wear rate, 1.04 × 10-5 mm3/Nm, of laser processed CoCrMo alloy tested under identical experimental conditions. In vitro biocompatibility study showed that these composite coatings were non-toxic and provides superior cell-material interactions compared to Ti6Al4V control, as a result of their high surface energy. In summary, excellent in vitro wear resistance and biocompatibility of present laser processed TiN reinforced Ti6Al4V alloy composite coatings clearly show their potential as wear resistant contact surfaces for load bearing implant applications. PMID:22301169

  18. Thermal activation of superheated lipid-coated perfluorocarbon drops.

    PubMed

    Mountford, Paul A; Thomas, Alec N; Borden, Mark A

    2015-04-28

    This study explored the thermal conditions necessary for the vaporization of superheated perfluorocarbon nanodrops. Droplets C3F8 and C4F10 coated with a homologous series of saturated diacylphosphatidylcholines were formed by condensation of 4 μm diameter microbubbles. These drops were stable at room temperature and atmospheric pressure, but they vaporized back into microbubbles at higher temperatures. The vaporization transition was measured as a function of temperature by laser light extinction. We found that C3F8 and C4F10 drops experienced 90% vaporization at 40 and 75 °C, respectively, near the theoretical superheat limits (80-90% of the critical temperature). We therefore conclude that the metastabilty of these phase-change agents arises not from the droplet Laplace pressure altering the boiling point, as previously reported, but from the metastability of the pure superheated fluid to homogeneous nucleation. The rate of C4F10 drop vaporization was quantified at temperatures ranging from 55 to 75 °C, and an apparent activation energy barrier was calculated from an Arrhenius plot. Interestingly, the activation energy increased linearly with acyl chain length from C14 to C20, indicating that lipid interchain cohesion plays an important role in suppressing the vaporization rate. The vaporized drops (microbubbles) were found to be unstable to dissolution at high temperatures, particularly for C14 and C16. However, proper choice of the fluorocarbon and lipid species provided a nanoemulsion that could undergo at least ten reversible condensation/vaporization cycles. The vaporization properties presented in this study may facilitate the engineering of tunable phase-shift particles for diagnostic imaging, targeted drug delivery, tissue ablation, and other applications.

  19. Active and Secretory IgA-Coated Bacterial Fractions Elucidate Dysbiosis in Clostridium difficile Infection

    PubMed Central

    Moya, Andrés; Vázquez-Castellanos, Jorge F.; Artacho, Alejandro; Chen, Xinhua; Kelly, Ciaran

    2016-01-01

    ABSTRACT The onset of Clostridium difficile infection (CDI) has been associated with treatment with wide-spectrum antibiotics. Antibiotic treatment alters the activity of gut commensals and may result in modified patterns of immune responses to pathogens. To study these mechanisms during CDI, we separated bacteria with high cellular RNA content (the active bacteria) and their inactive counterparts by fluorescence-activated cell sorting (FACS) of the fecal bacterial suspension. The gut dysbiosis due to the antibiotic treatment may result in modification of immune recognition of intestinal bacteria. The immune recognition patterns were assessed by FACS of bacterial fractions either coated or not with intestinal secretory immunoglobulin A (SIgA). We described the taxonomic distributions of these four bacterial fractions (active versus inactive and SIgA coated versus non-SIgA coated) by massive 16S rRNA gene amplicon sequencing and quantified the proportion of C. difficile toxin genes in the samples. The overall gut microbiome composition was more robustly influenced by antibiotics than by the C. difficile toxins. Bayesian networks revealed that the C. difficile cluster was preferentially SIgA coated during CDI. In contrast, in the CDI-negative group Fusobacterium was the characteristic genus of the SIgA-opsonized fraction. Lactobacillales and Clostridium cluster IV were mostly inactive in CDI-positive patients. In conclusion, although the proportion of C. difficile in the gut is very low, it is able to initiate infection during the gut dysbiosis caused by environmental stress (antibiotic treatment) as a consequence of decreased activity of the protective bacteria. IMPORTANCE C. difficile is a major enteric pathogen with worldwide distribution. Its expansion is associated with broad-spectrum antibiotics which disturb the normal gut microbiome. In this study, the DNA sequencing of highly active bacteria and bacteria opsonized by intestinal secretory immunoglobulin

  20. Phosphonium alkyl PEG sulfate ionic liquids as coating materials for activation of Burkholderia cepacia lipase.

    PubMed

    Matsubara, Yui; Kadotani, Shiho; Nishihara, Takashi; Hikino, Yoshichika; Fukaya, Yukinobu; Nokami, Toshiki; Itoh, Toshiyuki

    2015-12-01

    Lipases are among the most widely used enzymes applicable for various substrates; however, the slow reactions or poor enantioselective reactions are sometimes obtained. To develop ionic liquid type activating agents for lipase, four types of phosphonium cetyl(PEG)10 sulfate ionic liquids have been synthesized and used as coating materials of Burkholderia cepacia lipase (Lipase PS) through the lyophilization process. Tributyl ([2-methoxy]ethoxymethyl)phosphonium cetyl(PEG)10 sulfate ([P444MEM ][C16 (PEG)10 SO4 ]) (PL1) worked best among them, and PL1-coated lipase PS displayed high reactivity in transesterification of broad types of secondary alcohols using vinyl acetate as an acylating reagent with perfect enantioselectivity (E > 200). The substrate preference of PL1-PS differs from that of commercial lipase PS or [bdmim] [C16 (PEG)10 SO4 ]-coated lipase (IL1-PS); PL1-PS displayed excellent enantioselectivity in the reaction of 2-chloro-1-phenylethanol with E > 200, though insufficient E values were recorded for lipase PS (E = 12) and IL1-PS (E = 123) for this alcohol. PL1-PS also showed perfect enantioselectivity (E > 200) for the reaction of 1-(pyridin-2-yl)ethanol, while IL1-PS showed E = 130 for this compound. We further succeeded in demonstrating the recyclable use of PL1-PS five times in tributyl(3-methoxypropyl)phosphonium bis(trifluoromethylsulfonyl)amide ([P444PM ][Tf2 N]) as a solvent. Since PL1-PS is easily applicable to 10-20 gram-scaled reactions, it is expected that the IL-coated enzyme might be useful for practical preparation of a wide variety of chiral secondary alcohols.

  1. The Effect of Spray Distance and Scanning Step on the Coating Thickness Uniformity in Cold Spray Process

    NASA Astrophysics Data System (ADS)

    Cai, Zhenhua; Deng, Sihao; Liao, Hanlin; Zeng, Chunnian; Montavon, Ghislain

    2014-02-01

    In the process of cold spray applications, robot kinematic parameters represent significant influences on the coating quality. Those parameters include: spray distance, spray angle, gun relative velocity to substrate, scanning step, and cycle numbers. The combined effects which are caused by their interactions determine the coating thickness. The increasing requirements of coating productivity lead to the objectivity of analyzing the effect of robot kinematic parameters. So it becomes necessary to optimize the robot trajectory for spraying process in order to obtain a desired coating thickness. This study aims at investigating the relationship between the coating profile and the spray distance, scanning step, and introducing the basic principle of a software toolkit named thermal spray toolkit (TST) developed in our laboratory to generate the optimized robot trajectories in spray processes including thermal spray and cold spray. Experiments have been carried out to check the reliability of the simulated coating profile and the calculated coating thickness by TST.

  2. Formulation and process strategies to minimize coat damage for compaction of coated pellets in a rotary tablet press: A mechanistic view.

    PubMed

    Xu, Min; Heng, Paul Wan Sia; Liew, Celine Valeria

    2016-02-29

    Compaction of multiple-unit pellet system (MUPS) tablets has been extensively studied in the past few decades but with marginal success. This study aims to investigate the formulation and process strategies for minimizing pellet coat damage caused by compaction and elucidate the mechanism of damage sustained during the preparation of MUPS tablets in a rotary tablet press. Blends containing ethylcellulose-coated pellets and cushioning agent (spray dried aggregates of micronized lactose and mannitol), were compacted into MUPS tablets in a rotary tablet press. The effects of compaction pressure and dwell time on the physicomechanical properties of resultant MUPS tablets and extent of pellet coat damage were systematically examined. The coated pellets from various locations at the axial and radial peripheral surfaces and core of the MUPS tablets were excavated and assessed for their coat damage individually. Interestingly, for a MUPS tablet formulation which consolidates by plastic deformation, the tablet mechanical strength could be enhanced without exacerbating pellet coat damage by extending the dwell time in the compaction cycle during rotary tableting. However, the increase in compaction pressure led to faster drug release rate. The location of the coated pellets in the MUPS tablet also contributed to the extent of their coat damage, possibly due to uneven force distribution within the compact. To ensure viability of pellet coat integrity, the formation of a continuous percolating network of cushioning agent is critical and the applied compaction pressure should be less than the pellet crushing strength.

  3. Functionalization of PDMS modified and plasma activated two-component polyurethane coatings by surface attachment of enzymes

    NASA Astrophysics Data System (ADS)

    Kreider, Alexej; Richter, Katharina; Sell, Stephan; Fenske, Mandus; Tornow, Christian; Stenzel, Volkmar; Grunwald, Ingo

    2013-05-01

    This article describes a new strategy for coupling the enzyme horseradish peroxidase to a two-component polyurethane (2C-PUR) coating. A stable polymer conjugate was achieved by combining the enzyme and the 2C-PUR coating which was modified with poly(dimethylsiloxane) (PDMS), located at the surface. An atmospheric pressure plasma jet system was used to convert alkyl groups from the PDMS into polar silanol functionalities. This conversion was proven by X-ray photoelectron spectroscopy and dynamic contact angle measurements. In addition, the stability of the activated 2C-PUR surface containing silanol groups was determined by measuring the contact angle as a function of time. Compared to the non-modified 2C-PUR systems the one with PDMS displayed a higher stability over a time period over 28 h. In a silanization process the coating was treated with (3-aminopropyl) trimethoxysilane and the enzyme was subsequently immobilized to the coating via the cross linker glutaraldehyde to receive new biomimetic catalytic/enzymatic functions. The chemical immobilization (chemisorption) of the enzyme to the surface showed statistically significant higher biological activity as compared to references samples without using a cross linker (physisorption). The presented technique offers the opportunity to design new and smart multifunctional surface coatings which employ biomimetic capabilities.

  4. Internal porosity of mineral coating supports microbial activity in rapid sand filters for groundwater treatment.

    PubMed

    Gülay, Arda; Tatari, Karolina; Musovic, Sanin; Mateiu, Ramona V; Albrechtsen, Hans-Jørgen; Smets, Barth F

    2014-11-01

    A mineral coating develops on the filter grain surface when groundwater is treated via rapid sand filtration in drinking water production. The coating changes the physical and chemical properties of the filter material, but little is known about its effect on the activity, colonization, diversity, and abundance of microbiota. This study reveals that a mineral coating can positively affect the colonization and activity of microbial communities in rapid sand filters. To understand this effect, we investigated the abundance, spatial distribution, colonization, and diversity of all and of nitrifying prokaryotes in filter material with various degrees of mineral coating. We also examined the physical and chemical characteristics of the mineral coating. The amount of mineral coating correlated positively with the internal porosity, the packed bulk density, and the biologically available surface area of the filter material. The volumetric NH4 (+) removal rate also increased with the degree of mineral coating. Consistently, bacterial 16S rRNA and amoA abundances positively correlated with increased mineral coating levels. Microbial colonization could be visualized mainly within the outer periphery (60.6 ± 35.6 μm) of the mineral coating, which had a thickness of up to 600 ± 51 μm. Environmental scanning electron microscopic (E-SEM) observations suggested an extracellular polymeric substance-rich matrix and submicron-sized bacterial cells. Nitrifier diversity profiles were similar irrespective of the degree of mineral coating, as indicated by pyrosequencing analysis. Overall, our results demonstrate that mineral coating positively affects microbial colonization and activity in rapid sand filters, most likely due to increased volumetric cell abundances facilitated by the large surface area of internal mineral porosity accessible for microbial colonization.

  5. Processing-structure-property relationships of thermal barrier coatings deposited using the solution precursor plasma spray process

    NASA Astrophysics Data System (ADS)

    Xie, Liangde

    This research is intended to develop a novel process, solution-precursor plasma-spray (SPPS), for the deposition of highly durable thermal barrier coatings (TBCs). In the SPPS process a solution precursor feedstock, that results in ZrO2-7 wt% Y2O3 ceramic, is injected into the plasma jet and the coating is deposited on a metal substrate. The formed coating has the following novel microstructural features: (i) ultra-fine splats, (ii) through-thickness cracks, (iii) micrometer and nanometer porosity, and (iv) interpass boundaries. The deposition mechanisms of the solution precursor droplets injected into the different regions of the plasma jet were found to be different due to large temperature variation across the plasma jet. The solution precursor droplets injected into the core of the plasma jet are deposited on the substrate as ultra-fine splats that account for around 65 volume% of the coating. The other 35 volume% of the coating includes porosity and deposits formed from the solution precursor droplets injected into other regions of the plasma jet. The optimum processing condition for highly durable TBCs was determined using Taguchi design of experiments. Meanwhile, the relationship of the microstructural features and processing parameters was revealed. During thermal cycling, the unmelted particles in the coating were observed to pyloyze and/or sinter, while no sign of sintering was observed for the ultra-fine splats. The spacing of through-thickness cracks remains in the range of 160 to 190 mum throughout the thermal cycling test. Three stages of oxidation of the bond coat were observed. Failure of the SPPS TBC starts with the crack nucleation along the unmelted particles in the top coat and the Ni, Cr, Co-rich oxides of large thickness. These cracks propagate and coalesce with thermal cycling. The extensive cracking of the rapidly formed Ni, Cr, Co-rich oxides resulting from the depletion of aluminum in the bond coat leads to the development of large

  6. The structure and the photocatalytic activity of titania based nanotube and nanofiber coatings

    NASA Astrophysics Data System (ADS)

    Radtke, A.; Piszczek, P.; Topolski, A.; Lewandowska, Ż.; Talik, E.; Andersen, I. Hald; Nielsen, L. Pleth; Heikkilä, M.; Leskelä, M.

    2016-04-01

    The photocatalytic activity of TiO2 based nanotube (TNT) and nanofiber (TNF) coatings has been investigated, in correlation to their structure, morphology, specific surface area, acidity and the amount of surface H2O molecules and sbnd OH groups. Characterization of these materials was carried out using grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). The photocatalytic activity has been quantified by two different methods, based on the photodegradation of methylene blue (the pattern of water-soluble organic pollutant) and acetone (the pattern of volatile organic pollutant), respectively. Results of our investigations revealed that TNF coatings were significantly more active in case of both photodegradation processes in air and water, as compared to TNT, even if the specific surface area of TNF films was smaller than the adequate surface area of TNT. The microstructure of produced materials, the amount of adsorbed sbnd OH groups and H2O molecules located on the surface of materials, and the acidity of the surface, were the main factors which affect their photoactivity. Photocatalytic properties of tubular and porous TiO2-based materials are the resultant of the compilation of individual factors impact and any of them cannot be neglected.

  7. Enhancing absorption in coated semiconductor nanowire/nanorod core-shell arrays using active host matrices

    NASA Astrophysics Data System (ADS)

    Jule, Leta; Dejene, Francis; Roro, Kittessa

    2016-12-01

    In the present work, we investigated theoretically and experimentally the interaction of radiation field phenomena interacting with arrays of nanowire/nanorod core-shell embedded in active host matrices. The optical properties of composites are explored including the case when the absorption of propagating wave by dissipative component is completely compensated by amplification in active (lasing) medium. On the basis of more elaborated modeling approach and extended effective medium theory, the effective polarizability and the refractive index of electromagnetic mode dispersion of the core-shell nanowire arrays are derived. ZnS(shell)-coated by sulphidation process on ZnO(shell) nanorod arrays grown on (100) silicon substrate by chemical bath deposition (CBD) has been used for theoretical comparison. Compared with the bare ZnO nanorods, ZnS-coated core/shell nanorods exhibit a strongly reduced ultraviolet (UV) emission and a dramatically enhanced deep level (DL) emission. Obviously, the UV and DL emission peaks are attributed to the emissions of ZnO nanorods within ZnO/ZnS core/shell nanorods. The reduction of UV emission after ZnS coating seems to agree with the charge separation mechanism of type-II band alignment that holes transfer from the core to shell, which would quench the UV emission to a certain extent. Our theoretical calculations and numerical simulation demonstrate that the use of active host (amplifying) medium to compensate absorption at metallic inclusions. Moreover the core-shell nanorod/nanowire arrays create the opportunity for broad band absorption and light harvesting applications.

  8. Pretreatment process for forming a smooth surface diamond film on a carbon-coated substrate

    DOEpatents

    Feng, Z.; Brewer, M.; Brown, I.; Komvopoulos, K.

    1994-05-03

    A process is disclosed for the pretreatment of a carbon-coated substrate to provide a uniform high density of nucleation sites thereon for the subsequent deposition of a continuous diamond film without the application of a bias voltage to the substrate. The process comprises exposing the carbon-coated substrate, in a microwave plasma enhanced chemical vapor deposition system, to a mixture of hydrogen-methane gases, having a methane gas concentration of at least about 4% (as measured by partial pressure), while maintaining the substrate at a pressure of about 10 to about 30 Torr during the pretreatment. 6 figures.

  9. Pretreatment process for forming a smooth surface diamond film on a carbon-coated substrate

    DOEpatents

    Feng, Zhu; Brewer, Marilee; Brown, Ian; Komvopoulos, Kyriakos

    1994-01-01

    A process is disclosed for the pretreatment of a carbon-coated substrate to provide a uniform high density of nucleation sites thereon for the subsequent deposition of a continuous diamond film without the application of a bias voltage to the substrate. The process comprises exposing the carbon-coated substrate, in a microwave plasma enhanced chemical vapor deposition system, to a mixture of hydrogen-methane gases, having a methane gas concentration of at least about 4% (as measured by partial pressure), while maintaining the substrate at a pressure of about 10 to about 30 Torr during the pretreatment.

  10. Measurement methods and standards for processing and application of thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Dapkunas, S. J.

    1995-01-01

    Application of thermal barrier coatings deposited by thermal spray, physical vapor and possibly other methods is expected to be extended from aircraft gas turbines to industrial and utility gas turbines as well as diesel engines. This increased usage implies the participation of greater numbers of processors and users, making the availability of standards for process control and property measurement more important. Available standards for processing and evaluation of thermal barrier coatings are identified as well as those needed in the future but currently unavailable.

  11. The effect of silica-coating by sol-gel process on resin-zirconia bonding.

    PubMed

    Lung, Christie Ying Kei; Kukk, Edwin; Matinlinna, Jukka Pekka

    2013-01-01

    The effect of silica-coating by sol-gel process on the bond strength of resin composite to zirconia was evaluated and compared against the sandblasting method. Four groups of zirconia samples were silica-coated by sol-gel process under varied reagent ratios of ethanol, water, ammonia and tetraethyl orthosilicate and for different deposition times. One control group of zirconia samples were treated with sandblasting. Within each of these five groups, one subgroup of samples was kept in dry storage while another subgroup was aged by thermocycling for 6,000 times. Besides shear bond testing, the surface topography and surface elemental composition of silica-coated zirconia samples were also examined using scanning electron microscopy and X-ray photoelectron spectroscopy. Comparison of silica coating methods revealed significant differences in bond strength among the Dry groups (p<0.001) and Thermocycled groups (p<0.001). Comparison of sol-gel deposition times also revealed significant differences in bond strength among the Dry groups (p<0.01) and Thermocycled groups (p<0.001). Highest bond strengths were obtained after 141-h deposition: Dry (7.97±3.72 MPa); Thermocycled (2.33±0.79 MPa). It was concluded that silica-coating of zirconia by sol-gel process resulted in weaker resin bonding than by sandblasting.

  12. Recent advances in edible coatings for fresh and minimally processed fruits.

    PubMed

    Vargas, Maria; Pastor, Clara; Chiralt, Amparo; McClements, D Julian; González-Martínez, Chelo

    2008-06-01

    The development of new edible coatings with improved functionality and performance for fresh and minimally processed fruits is one of the challenges of the post harvest industry. In the past few years, research efforts have focused on the design of new eco-friendly coatings based on biodegradable polymers, which not only reduce the requirements of packaging but also lead to the conversion of by-products of the food industry into value added film-forming components. This work reviews the different coating formulations and applications available at present, as well as the main results of the most recent investigations carried out on the topic. Traditionally, edible coatings have been used as a barrier to minimize water loss and delay the natural senescence of coated fruits through selective permeability to gases. However, the new generation of edible coatings is being especially designed to allow the incorporation and/or controlled release of antioxidants, vitamins, nutraceuticals, and natural antimicrobial agents by means of the application of promising technologies such as nanoencapsulation and the layer-by-layer assembly.

  13. Fabrication and Microstructure of Hydroxyapatite Coatings on Zirconia by Room Temperature Spray Process.

    PubMed

    Seo, Dong Seok; Chae, Hak Cheol; Lee, Jong Kook

    2015-08-01

    Hydroxyapatite coatings were fabricated on zirconia substrates by a room temperature spray process and were investigated with regards to their microstructure, composition and dissolution in water. An initial hydroxyapatite powder was prepared by heat treatment of bovine-bone derived powder at 1100 °C for 2 h, while dense zirconia substrates were fabricated by pressing 3Y-TZP powder and sintering it at 1350 °C for 2 h. Room temperature spray coating was performed using a slit nozzle in a low pressure-chamber with a controlled coating time. The phase composition of the resultant hydroxyapatite coatings was similar to that of the starting powder, however, the grain size of the hydroxyapatite particles was reduced to about 100 nm due to their formation by particle impaction and fracture. All areas of the coating had a similar morphology, consisting of reticulated structure with a high surface roughness. The hydroxyapatite coating layer exhibited biostability in a stimulated body fluid, with no severe dissolution being observed during in vitro experimentation.

  14. Apparatus and process for depositing hard coating in a nozzle orifice

    DOEpatents

    Flynn, P.L.; Giammarise, A.W.

    1994-12-20

    The present invention is directed to a process for coating the interior surfaces of an orifice in a substrate that forms a slurry fuel injection nozzle. In a specific embodiment, the nozzle is part of a fuel injection system for metering a coal-water slurry into a large, medium-speed, multi-cylinder diesel engine. In order to retard erosion of the orifice, the substrate is placed in a chemical vapor deposition (CVD) reaction chamber. A reaction gas is passed into the chamber at a gas temperature below its reaction temperature and is directed through the orifice in the substrate. The gas reaction temperature is a temperature at and above which the reaction gas deposits as a coating, and the reaction gas is of a composition whereby improved resistance to erosion by flow of the particulates in the slurry fuel is imparted by the deposited coating. Only the portion of the substrate in proximity to the orifice to be coated is selectively heated to at least the gas reaction temperature for effecting coating of the orifice's interior surfaces by the vapor deposited coating formed from the reaction gas. 2 figures.

  15. Apparatus and process for depositing hard coating in a nozzle orifice

    DOEpatents

    Flynn, Paul L.; Giammarise, Anthony W.

    1994-01-01

    The present invention is directed to a process for coating the interior surfaces of an orifice in a substrate that forms a slurry fuel injection nozzle. In a specific embodiment, the nozzle is part of a fuel injection system for metering a coal-water slurry into a large, medium-speed, multi-cylinder diesel engine. In order to retard erosion of the orifice, the substrate is placed in a chemical vapor deposition (CVD) reaction chamber. A reaction gas is passed into the chamber at a gas temperature below its reaction temperature and is directed through the orifice in the substrate. The gas reaction temperature is a temperature at and above which the reaction gas deposits as a coating, and the reaction gas is of a composition whereby improved resistance to erosion by flow of the particulates in the slurry fuel is imparted by the deposited coating. Only the portion of the substrate in proximity to the orifice to be coated is selectively heated to at least the gas reaction temperature for effecting coating of the orifice's interior surfaces by the vapor deposited coating formed from the reaction gas.

  16. Active Inference: A Process Theory.

    PubMed

    Friston, Karl; FitzGerald, Thomas; Rigoli, Francesco; Schwartenbeck, Philipp; Pezzulo, Giovanni

    2017-01-01

    This article describes a process theory based on active inference and belief propagation. Starting from the premise that all neuronal processing (and action selection) can be explained by maximizing Bayesian model evidence-or minimizing variational free energy-we ask whether neuronal responses can be described as a gradient descent on variational free energy. Using a standard (Markov decision process) generative model, we derive the neuronal dynamics implicit in this description and reproduce a remarkable range of well-characterized neuronal phenomena. These include repetition suppression, mismatch negativity, violation responses, place-cell activity, phase precession, theta sequences, theta-gamma coupling, evidence accumulation, race-to-bound dynamics, and transfer of dopamine responses. Furthermore, the (approximately Bayes' optimal) behavior prescribed by these dynamics has a degree of face validity, providing a formal explanation for reward seeking, context learning, and epistemic foraging. Technically, the fact that a gradient descent appears to be a valid description of neuronal activity means that variational free energy is a Lyapunov function for neuronal dynamics, which therefore conform to Hamilton's principle of least action.

  17. Enhanced Photoelectrochemical Activity of ZnO-Coated TiO2 Nanotubes and Its Dependence on ZnO Coating Thickness

    NASA Astrophysics Data System (ADS)

    Cai, Hua; Liang, Peipei; Hu, Zhigao; Shi, Liqun; Yang, Xu; Sun, Jian; Xu, Ning; Wu, Jiada

    2016-02-01

    One-dimensional heterogeneous nanostructures in the form of ZnO-coated TiO2 nanotubes (ZnO/TiO2 NTs) were fabricated by atomic layer deposition of an ultrathin ZnO coating on electrochemical anodization-formed TiO2 nanotubes (NTs) with the thickness of ZnO coating being precisely controlled at atomic scale, and the photoelectrochemical activity of the fabricated ZnO/TiO2 NTs and the influence of ZnO coating and its thickness were studied. The structures of TiO2 NTs and ZnO coatings were characterized by X-ray diffraction, Raman backscattering spectroscopy, and transmission electron microscopy. The photoelectrochemical activity was studied through the measurements of electrochemical impendence, flat-band potential, and transient photocurrent density. The TiO2 NTs exhibit anatase structure, and the ZnO coatings are structured with hexagonal wurtzite. The photoelectrochemical activity of the ZnO/TiO2 NTs is strongly dependent on the thickness of ZnO coating. ZnO/TiO2 NTs with a thinner rather than a thicker ZnO coating exhibit better photoelectrochemical activity with reduced charge transfer resistance, increased negative flat-band potentials, and enhanced photocurrent densities. Under visible illumination, an increase of about 60 % in the photoelectrochemical activity is obtained for ZnO/TiO2 NTs with an about 2-nm-thick ZnO coating.

  18. Enhanced Photoelectrochemical Activity of ZnO-Coated TiO2 Nanotubes and Its Dependence on ZnO Coating Thickness.

    PubMed

    Cai, Hua; Liang, Peipei; Hu, Zhigao; Shi, Liqun; Yang, Xu; Sun, Jian; Xu, Ning; Wu, Jiada

    2016-12-01

    One-dimensional heterogeneous nanostructures in the form of ZnO-coated TiO2 nanotubes (ZnO/TiO2 NTs) were fabricated by atomic layer deposition of an ultrathin ZnO coating on electrochemical anodization-formed TiO2 nanotubes (NTs) with the thickness of ZnO coating being precisely controlled at atomic scale, and the photoelectrochemical activity of the fabricated ZnO/TiO2 NTs and the influence of ZnO coating and its thickness were studied. The structures of TiO2 NTs and ZnO coatings were characterized by X-ray diffraction, Raman backscattering spectroscopy, and transmission electron microscopy. The photoelectrochemical activity was studied through the measurements of electrochemical impendence, flat-band potential, and transient photocurrent density. The TiO2 NTs exhibit anatase structure, and the ZnO coatings are structured with hexagonal wurtzite. The photoelectrochemical activity of the ZnO/TiO2 NTs is strongly dependent on the thickness of ZnO coating. ZnO/TiO2 NTs with a thinner rather than a thicker ZnO coating exhibit better photoelectrochemical activity with reduced charge transfer resistance, increased negative flat-band potentials, and enhanced photocurrent densities. Under visible illumination, an increase of about 60 % in the photoelectrochemical activity is obtained for ZnO/TiO2 NTs with an about 2-nm-thick ZnO coating.

  19. Development of an enteric coating formulation and process for tablets primarily composed of a highly water-soluble, organic acid.

    PubMed

    Crotts, G; Sheth, A; Twist, J; Ghebre-Sellassie, I

    2001-01-01

    The purpose of this study was to define coating conditions for the enteric coating of a highly water soluble, acidic tablet core. Acidic tablet cores containing a marker drug were separated into three groups and seal coated to coverage levels of 0% (uncoated, white), 1% (yellow), and 3% (tan) weight gains. By employing a 'color coding' scheme, the different seal coated tablets could be coated simultaneously to reduce the number of experiments and eliminate potential differences that may exist during separate coating processes. In addition, an allotment of each coded tablet type was sequentially numbered with a marker pen, weighed, and recorded in order to identify the precise level of enteric coating as well as to monitor the variability of a given coating operation. The tablets were coated with five Eudragit((R)) L30D-based enteric formulations containing different amounts of plasticizer (10-20 parts) and talc (10-50 parts). During each enteric coating process, a predetermined amount of labeled tablets were removed after attaining 6, 8, and 10% weight gains. The labeled tablets were re-weighed, sorted, and then tested using USP disintegration and dissolution methods. Weight gain measurements of individual tablets indicated low coating variability (6.2% RSD) during the enteric coating processes. Dissolution results revealed that all enteric coat formulations inhibited drug release for 2 h in 0.1 N HCl. In contrast, it was found that tablets without a seal coat failed the USP disintegration test. In addition, seal coated tablets exhibited ca. 1.5-5 fold greater drug release at most intermediate sampling time points in phosphate buffer, pH 6.8, than tablets without a seal coat, suggesting that the dissolution of the latter was delayed by the generation of an acidic microenvironment at the interface of the enteric coat/acidic tablet core. Prior to enteric coating an acidic, highly water soluble substrate, a seal coat barrier should be applied to prevent retardation in

  20. Kinetics of the process of formation and high-temperature oxidation of electrospark coatings on steel

    SciTech Connect

    Verkhoturov, A.D.; Chiplik, V.N.; Egorov, F.F.; Lavrenko, V.A.; Podchernyaeva, I.A.; Shemet, V.Z.

    1986-10-01

    This work is a study of the kinetics of formation and of the heat resistance of electrospark coatings based on the composite TiB/sub 2/-Mo with varying molybdenum content. In the process of electrospark alloying they measured the specific erosion of the anode and the increase in weight of the cathode with an accuracy not worse than 5%. Electrospark coatings of TiB/sub 2/-Mo on steel 45 are marked by improved scaling resistance at temperatures above 900 C. Their scaling resistance and also the effectiveness of the process of electrospark alloying increase with increasing content of the phase B-MoB in the coating because molybdenum borate forms during its high-temperature oxidation. Illustrations and table are included.

  1. Constitutive activated Cdc42-associated kinase (Ack) phosphorylation at arrested endocytic clathrin-coated pits of cells that lack dynamin

    PubMed Central

    Shen, Hongying; Ferguson, Shawn M.; Dephoure, Noah; Park, Ryan; Yang, Yan; Volpicelli-Daley, Laura; Gygi, Steven; Schlessinger, Joseph; De Camilli, Pietro

    2011-01-01

    Clathrin-mediated endocytosis is a fundamental cellular process conserved from yeast to mammals and is an important endocytic route for the internalization of many specific cargos, including activated growth factor receptors. Here we examined changes in tyrosine phosphorylation, a representative output of growth factor receptor signaling, in cells in which endocytic clathrin-coated pits are frozen at a deeply invaginated state, that is, cells that lack dynamin (fibroblasts from dynamin 1, dynamin 2 double conditional knockout mice). The major change observed in these cells relative to wild-type cells was an increase in the phosphorylation state, and thus activation, of activated Cdc42-associated kinase (Ack), a nonreceptor tyrosine kinase. Ack is concentrated at clathrin-coated pits, and binds clathrin heavy chain via two clathrin boxes. RNA interference–based approaches and pharmacological manipulations further demonstrated that the phosphorylation of Ack requires both clathrin assembly into endocytic clathrin-coated pits and active Cdc42. These findings reveal a link between progression of clathrin-coated pits to endocytic vesicles and an activation–deactivation cycle of Ack. PMID:21169560

  2. A novel in-line NIR spectroscopy application for the monitoring of tablet film coating in an industrial scale process.

    PubMed

    Möltgen, C-V; Puchert, T; Menezes, J C; Lochmann, D; Reich, G

    2012-04-15

    Film coating of tablets is a multivariate pharmaceutical unit operation. In this study an innovative in-line Fourier-Transform Near-Infrared Spectroscopy (FT-NIRS) application is described which enables real-time monitoring of a full industrial scale pan coating process of heart-shaped tablets. The tablets were coated with a thin hydroxypropyl methylcellulose (HPMC) film of up to approx. 28 μm on the tablet face as determined by SEM, corresponding to a weight gain of 2.26%. For a better understanding of the aqueous coating process the NIR probe was positioned inside the rotating tablet bed. Five full scale experimental runs have been performed to evaluate the impact of process variables such as pan rotation, exhaust air temperature, spray rate and pan load and elaborate robust and selective quantitative calibration models for the real-time determination of both coating growth and tablet moisture content. Principal Component (PC) score plots allowed each coating step, namely preheating, spraying and drying to be distinguished and the dominating factors and their spectral effects to be identified (e.g. temperature, moisture, coating growth, change of tablet bed density, and core/coat interactions). The distinct separation of HPMC coating growth and tablet moisture in different PCs enabled a real-time in-line monitoring of both attributes. A PLS calibration model based on Karl Fischer reference values allowed the tablet moisture trajectory to be determined throughout the entire coating process. A 1-latent variable iPLS weight gain calibration model with calibration samples from process stages dominated by the coating growth (i.e. ≥ 30% of the theoretically applied amount of coating) was sufficiently selective and accurate to predict the progress of the thin HPMC coating layer. At-line NIR Chemical Imaging (NIR-CI) in combination with PLS Discriminant Analysis (PLSDA) verified the HPMC coating growth and physical changes at the core/coat interface during the initial

  3. Bond Strength of Multicomponent White Cast Iron Coatings Applied by HVOF Thermal Spray Process

    NASA Astrophysics Data System (ADS)

    Maranho, Ossimar; Rodrigues, Daniel; Boccalini, Mario; Sinatora, Amilton

    2009-12-01

    Multicomponent white cast iron is a new alloy that belongs to system Fe-C-Cr-W-Mo-V, and because of its excellent wear resistance it is used in the manufacture of hot rolling mills rolls. To date, this alloy has been processed by casting, powder metallurgy, and spray forming. The high-velocity oxyfuel process is now also considered for the manufacture of components with this alloy. The effects of substrate, preheating temperature, and coating thickness on bond strength of coatings have been determined. Substrates of AISI 1020 steel and of cast iron with preheating of 150 °C and at room temperature were used to apply coatings with 200 and 400 μm nominal thickness. The bond strength of coatings was measured with the pull-off test method and the failure mode by scanning electron microscopic analysis. Coatings with thickness of 200 μm and applied on substrates of AISI 1020 steel with preheating presented bond strength of 87 ± 4 MPa.

  4. TRISO-Coated Fuel Processing to Support High Temperature Gas-Cooled Reactors

    SciTech Connect

    Del Cul, G.D.

    2002-10-01

    The initial objective of the work described herein was to identify potential methods and technologies needed to disassemble and dissolve graphite-encapsulated, ceramic-coated gas-cooled-reactor spent fuels so that the oxide fuel components can be separated by means of chemical processing. The purpose of this processing is to recover (1) unburned fuel for recycle, (2) long-lived actinides and fission products for transmutation, and (3) other fission products for disposal in acceptable waste forms. Follow-on objectives were to identify and select the most promising candidate flow sheets for experimental evaluation and demonstration and to address the needs to reduce technical risks of the selected technologies. High-temperature gas-cooled reactors (HTGRs) may be deployed in the next -20 years to (1) enable the use of highly efficient gas turbines for producing electricity and (2) provide high-temperature process heat for use in chemical processes, such as the production of hydrogen for use as clean-burning transportation fuel. Also, HTGR fuels are capable of significantly higher burn-up than light-water-reactor (LWR) fuels or fast-reactor (FR) fuels; thus, the HTGR fuels can be used efficiently for transmutation of fissile materials and long-lived actinides and fission products, thereby reducing the inventory of such hazardous and proliferation-prone materials. The ''deep-burn'' concept, described in this report, is an example of this capability. Processing of spent graphite-encapsulated, ceramic-coated fuels presents challenges different from those of processing spent LWR fuels. LWR fuels are processed commercially in Europe and Japan; however, similar infrastructure is not available for processing of the HTGR fuels. Laboratory studies on the processing of HTGR fuels were performed in the United States in the 1960s and 1970s, but no engineering-scale processes were demonstrated. Currently, new regulations concerning emissions will impact the technologies used in

  5. Impact of Processing Conditions on Inter-tablet Coating Thickness Variations Measured by Terahertz In-Line Sensing

    PubMed Central

    Lin, Hungyen; May, Robert K; Evans, Michael J; Zhong, Shuncong; Gladden, Lynn F; Shen, Yaochun; Zeitler, J Axel

    2015-01-01

    A novel in-line technique utilising pulsed terahertz radiation for direct measurement of the film coating thickness of individual tablets during the coating process was previously developed and demonstrated on a production-scale coater. Here, we use this technique to monitor the evolution of tablet film coating thickness and its inter-tablet variability during the coating process under a number of different process conditions that have been purposefully induced in the production-scale coating process. The changes that were introduced to the coating process include removing the baffles from the coater, adding uncoated tablets to the running process, halting the drum, blockage of spray guns and changes to the spray rate. The terahertz sensor was able to pick up the resulting changes in average coating thickness in the coating drum and we report the impact of these process changes on the resulting coating quality. © 2015 The Authors. Journal of Pharmaceutical Sciences published by Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:2513–2522, 2015 PMID:26037660

  6. Silver activation on thin films of Ag-ZrCN coatings for antimicrobial activity.

    PubMed

    Ferreri, I; Calderon V, S; Escobar Galindo, R; Palacio, C; Henriques, M; Piedade, A P; Carvalho, S

    2015-10-01

    Nowadays, with the increase of elderly population and related health problems, knee and hip joint prosthesis are being widely used worldwide. However, failure of these invasive devices occurs in a high percentage thus demanding the revision of the chirurgical procedure. Within the reasons of failure, microbial infections, either hospital or subsequently-acquired, contribute in high number to the statistics. Staphylococcus epidermidis (S. epidermidis) has emerged as one of the major nosocomial pathogens associated with these infections. Silver has a historic performance in medicine due to its potent antimicrobial activity, with a broad-spectrum on the activity of different types of microorganisms. Consequently, the main goal of this work was to produce Ag-ZrCN coatings with antimicrobial activity, for the surface modification of hip prostheses. Thin films of ZrCN with several silver concentrations were deposited onto stainless steel 316 L, by DC reactive magnetron sputtering, using two targets, Zr and Zr with silver pellets (Zr+Ag target), in an atmosphere containing Ar, C2H2 and N2. The antimicrobial activity of the modified surfaces was tested against S. epidermidis and the influence of an activation step of silver was assessed by testing samples after immersion in a 5% (w/v) NaClO solution for 5 min. The activation procedure revealed to be essential for the antimicrobial activity, as observed by the presence of an inhibition halo on the surface with 11 at.% of Ag. The morphology analysis of the surface before and after the activation procedure revealed differences in silver distribution indicating segregation/diffusion of the metallic element to the film's surface. Thus, the results indicate that the silver activation step is responsible for an antimicrobial effect of the coatings, due to silver oxidation and silver ion release.

  7. Processing of hydroxylapatite coatings on titanium alloy bone prostheses

    DOEpatents

    Nastasi, Michael A.; Levine, Timothy E.; Mayer, James W.; Pizziconi, Vincent B.

    1998-01-01

    Processing of hydroxylapatite sol-gel films on titanium alloy bone prostheses. A method utilizing non-line-of-sight ion beam implantation and/or rapid thermal processing to provide improved bonding of layers of hydroxylapatite to titanium alloy substrates while encouraging bone ingrowth into the hydroxylapatite layers located away from the substrate, is described for the fabrication of prostheses. The first layer of hydroxylapatite is mixed into the substrate by the ions or rapidly thermally annealed, while subsequent layers are heat treated or densified using ion implantation to form layers of decreasing density and larger crystallization, with the outermost layers being suitable for bone ingrowth.

  8. Processing of hydroxylapatite coatings on titanium alloy bone prostheses

    DOEpatents

    Nastasi, M.A.; Levine, T.E.; Mayer, J.W.; Pizziconi, V.B.

    1998-10-06

    Processing of hydroxylapatite sol-gel films on titanium alloy bone prostheses. A method utilizing non-line-of-sight ion beam implantation and/or rapid thermal processing to provide improved bonding of layers of hydroxylapatite to titanium alloy substrates while encouraging bone ingrowth into the hydroxylapatite layers located away from the substrate, is described for the fabrication of prostheses. The first layer of hydroxylapatite is mixed into the substrate by the ions or rapidly thermally annealed, while subsequent layers are heat treated or densified using ion implantation to form layers of decreasing density and larger crystallization, with the outermost layers being suitable for bone ingrowth.

  9. Structurally Integrated Coatings for Wear and Corrosion (SICWC): Arc Lamp, InfraRed (IR) Thermal Processing

    SciTech Connect

    Mackiewicz-Ludtka, G.; Sebright, J.

    2007-12-15

    The primary goal of this Cooperative Research and Development Agreement (CRADA) betwe1311 UT-Battelle (Contractor) and Caterpillar Inc. (Participant) was to develop the plasma arc lamp (PAL), infrared (IR) thermal processing technology 1.) to enhance surface coating performance by improving the interfacial bond strength between selected coatings and substrates; and 2.) to extend this technology base for transitioning of the arc lamp processing to the industrial Participant. Completion of the following three key technical tasks (described below) was necessary in order to accomplish this goal. First, thermophysical property data sets were successfully determined for composite coatings applied to 1010 steel substrates, with a more limited data set successfully measured for free-standing coatings. These data are necessary for the computer modeling simulations and parametric studies to; A.) simulate PAL IR processing, facilitating the development of the initial processing parameters; and B.) help develop a better understanding of the basic PAL IR fusing process fundamentals, including predicting the influence of melt pool stirring and heat tnmsfar characteristics introduced during plasma arc lamp infrared (IR) processing; Second, a methodology and a set of procedures were successfully developed and the plasma arc lamp (PAL) power profiles were successfully mapped as a function of PAL power level for the ORNL PAL. The latter data also are necessary input for the computer model to accurately simulate PAL processing during process modeling simulations, and to facilitate a better understand of the fusing process fundamentals. Third, several computer modeling codes have been evaluated as to their capabilities and accuracy in being able to capture and simulate convective mixing that may occur during PAL thermal processing. The results from these evaluation efforts are summarized in this report. The intention of this project was to extend the technology base and provide for

  10. Multi-Energy Processing for Novel Coating Technologies

    DTIC Science & Technology

    2014-12-18

    STATEMENT 13. SUPPLEMENTARY NOTES 14. ABSTRACT Due to the wide range of superior properties, diamonds are of great interest in industry applications...and scientific research. The inherent shortcomings of conventional chemical vapor deposition (CVD) methods and the ever-increasing demand for diamonds ...urge extended efforts for further enhancement of diamond deposition without compromising the diamond quality. Conventional CVD processes, which rely

  11. Development of industrial ion implantation and ion assisted coating processes: A perspective

    NASA Astrophysics Data System (ADS)

    Legg, Keith O.; Solnick-Legg, Hillary

    1989-04-01

    Ion beam processes have gone through a series of developmental stages, from being the mainstay of the semiconductor industry for production of integrated circuits, to new commercial processes for biomedical, aerospace and other industries. Although research is still continuing on surface modification using ion beam methods, ion implantation and ion assisted coatings for treatment of metals, ceramics, polymers and composites must now be considered viable industrial processes of benefit in a wide variety of applications. However, ion implantation methods face various barriers to acceptability, in terms not only of other surface treatment processes, but for implantation itself. This paper will discuss some of the challenges faced by a small company whose primary business is development and marketing of ion implantation and ion-assisted coating processes.

  12. Spacecraft materials guide. [including: encapsulants and conformal coatings; optical materials; lubrication; and, bonding and joining processes

    NASA Technical Reports Server (NTRS)

    Staugaitis, C. L. (Editor)

    1975-01-01

    Materials which have demonstrated their suitability for space application are summarized. Common, recurring problems in encapsulants and conformal coatings, optical materials, lubrication, and bonding and joining are noted. The subjects discussed include: low density and syntactic foams, electrical encapsulants; optical glasses, interference filter, mirrors; oils, greases, lamillar lubricants; and, soldering and brazing processes.

  13. PROCESS OF COATING WITH NICKEL BY THE DECOMPOSITION OF NICKEL CARBONYL

    DOEpatents

    Hoover, T.B.

    1959-04-01

    An improved process is presented for the deposition of nickel coatings by the thermal decomposition of nickel carbonyl vapor. The improvement consists in incorporating a small amount of hydrogen sulfide gas in the nickel carbonyl plating gas. It is postulated that the hydrogen sulfide functions as a catalyst. i

  14. Processing Methods Established To Fabricate Porous Oxide Ceramic Spheres for Thermal Barrier Coating Applications

    NASA Technical Reports Server (NTRS)

    Dynys, Frederick W.

    2003-01-01

    As gas turbine technology advances, the demand for efficient engines and emission reduction requires a further increase in operating temperatures, but combustion temperatures are currently limited by the temperature capability of the engine components. The existing thermal barrier coating (TBC) technology does not provide sufficient thermal load reduction at a 3000 F (1649 C) operating condition. Advancement in thermal barrier coating technology is needed to meet this aggressive goal. One concept for improving thermal barrier coating effectiveness is to design coating systems that incorporate a layer that reflects or scatters photon radiation. This can be achieved by using porous structures. The refractive index mismatch between the solid and pore, the pore size, and the pore density can be engineered to efficiently scatter photon radiation. Under NASA s Ultra-Efficient Engine Technology (UEET) Program, processing methods to fabricate porous ceramic spheres suitable for scattering photon radiation at elevated temperatures have been established. A straightforward templating process was developed at the NASA Glenn Research Center that requires no special processing equipment. The template was used to define particle shape, particle size, and pore size. Spherical organic cation exchange resins were used as a structure-directing template. The cation exchange resins have dual template capabilities that can produce different pore architectures. This process can be used to fabricate both metal oxide and metal carbide spheres.

  15. EVALUATION OF CONVERGENT SPRAY TECHNOLOGYTM SPRAY PROCESS FOR ROOF COATING APPLICATION

    EPA Science Inventory

    The overall goal of this project was to demonstrate the feasibility of Convergent Spray TechnologyTM for the roofing industry. This was accomplished by producing an environmentally compliant coating utilizing recycled materials, a CSTTM spray process portable application cart, a...

  16. 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.

  17. Active Electrochemical Plasmonic Switching on Polyaniline-Coated Gold Nanocrystals.

    PubMed

    Lu, Wenzheng; Jiang, Nina; Wang, Jianfang

    2017-02-01

    High-performance electrochemical plasmonic switching is realized on both single-particle and ensemble levels by coating polyaniline on colloidal gold nanocrystals through surfactant-assisted oxidative polymerization. Under small applied potentials, the core@shell nanostructures exhibit reversible plasmon shifts as large as 150 nm, a switching time of less than 10 ms, and a high switching stability.

  18. Optimised process and formulation conditions for extended release dry polymer powder-coated pellets.

    PubMed

    Terebesi, Ildikó; Bodmeier, Roland

    2010-05-01

    The objective of this study was to improve the film formation and permeability characteristics of extended release ethylcellulose coatings prepared by dry polymer powder coating for the release of drugs of varying solubility. Ethylcellulose (7 and 10 cp viscosity grades) and Eudragit(R) RS were used for dry powder coating of pellets in a fluidised bed ball coater. Pre-plasticised ethylcellulose powder was prepared by spray-drying aqueous ethylcellulose dispersions (Surelease(R) and Aquacoat(R)) or by hot melt extrusion/cryogenic grinding of plasticised ethylcellulose. Chlorpheniramine maleate and theophylline were used as model drugs of different solubilities. The film formation process, polymeric films and coated pellets were characterised by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM) and dissolution testing. Film formation and extended drug release was achieved with ethylcellulose, a polymer with a high glass transition temperature (T(g)) without the use of water, which is usually required in dry powder coating. DMA-measurements revealed that plasticised ethylcellulose had a modulus of elasticity (E') similar to the low T(g) Eudragit(R) RS. With increasing plasticiser concentration, the T(g) of ethylcellulose was reduced and the mechanical properties improved, thus facilitating coalescence of the polymer particles. SEM-pictures revealed the formation of a dense, homogeneous film. The lower viscosity grade ethylcellulose (7 cp) resulted in better film formation than the higher viscosity grade (10 cp) and required less stringent curing conditions. Successful extended release ethylcellulose coatings were also obtained by coating with pre-plasticised spray-dried ethylcellulose powders as an alternative to the separate application of pure ethylcellulose powder and plasticiser. The permeability of the extended release coating could be controlled by using powder blends of ethylcellulose with the

  19. COATINGS FOR PROTECTION OF EQUIPMENT FOR BIOCHEMICAL PROCESSING OF GEOTHERMAL RESIDUES: PROGRESS REPORT FY 97

    SciTech Connect

    ALLAN,M.L.

    1997-11-01

    Thermal sprayed ethylene methacrylic acid (EMAA) and ethylene tetrafluoroethylene (ETFE), spray-and-bake ETFE and polyvinylidene fluoride (PVDF) and brushable ceramic-epoxy coatings were evaluated for corrosion protection in a biochemical process to treat geothermal residues. The findings are also relevant to other moderate temperature brine environments where corrosion is a problem. Coupon, Atlas cell, peel strength, cathodic disbondment and abrasion tests were performed in aggressive environments including geothermal sludge, hypersaline brine and sulfur-oxidizing bacteria (Thiobadus ferrooxidans) to determine suitability for protecting storage tanks and reaction vessels. It was found that all of the coatings were resistant to chemical attack and biodegradation at the test temperature of 55 C. The EMAA coatings protected 316L stainless steel from corrosion in coupon tests. However, corrosion of mild steel substrates thermal sprayed with EMAA and ETFE occurred in Atlas cell tests that simulated a lined reactor operating environment and this resulted in decreased adhesive strength. Peel tests to measure residual adhesion revealed that failure mode was dependent on exposure conditions. Long-term tests on the durability of ceramic-epoxy coatings in brine and bacteria are ongoing. Initial indications are that this coating has suitable characteristics. Abrasion tests showed that the ceramic-epoxy had good resistance to the abrasive effects of sludge. Thermal sprayed EMAA coatings also displayed abrasion resistance. Cathodic disbondment tests in brine at room temperature indicated that EMAA coatings are resistant to disbondment at applied potentials of {minus}780 to {minus}1,070 mV SCE for the test conditions and duration. Slight disbondment of one specimen occurred at a potential of {minus}1,500 mV SCE. The EMAA may be suited to use in conjunction with cathodic protection although further long-term, higher temperature testing would be needed.

  20. Laser processing of solar cells with anti-reflective coating

    DOEpatents

    Harley, Gabriel; Smith, David D.; Dennis, Tim; Waldhauer, Ann; Kim, Taeseok; Cousins, Peter John

    2016-02-16

    Contact holes of solar cells are formed by laser ablation to accommodate various solar cell designs. Use of a laser to form the contact holes is facilitated by replacing films formed on the diffusion regions with a film that has substantially uniform thickness. Contact holes may be formed to deep diffusion regions to increase the laser ablation process margins. The laser configuration may be tailored to form contact holes through dielectric films of varying thicknesses.

  1. Dry powder process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs

    NASA Technical Reports Server (NTRS)

    Wilkinson, Steven P. (Inventor); Johnston, Norman J. (Inventor); Marchello, Joseph M. (Inventor)

    1997-01-01

    A process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs is provided. A plurality of polymer powder coated filamentary towpregs are provided. The towpregs are collimated so that each towpreg is parallel. A material is applied to each side of the towpreg to form a sandwich. The sandwich is heated to a temperature wherein the polymer flows and intimately contacts the filaments and pressure is repeatedly applied perpendicularly to the sandwich with a longitudinal oscillating action wherein the filaments move apart and the polymer wets the filaments forming a uni-tape prepreg. The uni-tape prepreg is subsequently cooled.

  2. A Dry Powder Process for Preparing Uni-Tape Prepreg from Polymer Powder Coated Filamentary Towpregs

    NASA Technical Reports Server (NTRS)

    Wilkinson, Steven P. (Inventor); Johnston, Norman J. (Inventor); Marchello, Joseph M. (Inventor)

    1995-01-01

    A process for preparing uni-tape prepreg from polymer powder coated filamentary towpregs is provided. A plurality of polymer powder coated filamentary towpregs are provided. The towpregs are collimated so that each towpreg is parallel. The sandwich is heated to a temperature wherein the polymer flows and intimately contacts the filaments and pressure is repeatedly applied perpendicularly to the sandwich with a longitudinal oscillating action wherein the filaments move apart and the polymer wets the filaments forming a uni-tape prepreg. The uni-tape prepreg is subsequently cooled.

  3. Antimicrobial activity of silica coated silicon nano-tubes (SCSNT) and silica coated silicon nano-particles (SCSNP) synthesized by gas phase condensation.

    PubMed

    Tank, Chiti; Raman, Sujatha; Karan, Sujoy; Gosavi, Suresh; Lalla, Niranjan P; Sathe, Vasant; Berndt, Richard; Gade, W N; Bhoraskar, S V; Mathe, Vikas L

    2013-06-01

    Silica-coated, silicon nanotubes (SCSNTs) and silica-coated, silicon nanoparticles (SCSNPs) have been synthesized by catalyst-free single-step gas phase condensation using the arc plasma process. Transmission electron microscopy and scanning tunneling microscopy showed that SCSNTs exhibited a wall thickness of less than 1 nm, with an average diameter of 14 nm and a length of several 100 nm. Both nano-structures had a high specific surface area. The present study has demonstrated cheaper, resistance-free and effective antibacterial activity in silica-coated silicon nano-structures, each for two Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC) was estimated, using the optical densitometric technique, and by determining colony-forming units. The MIC was found to range in the order of micrograms, which is comparable to the reported MIC of metal oxides for these bacteria. SCSNTs were found to be more effective in limiting the growth of multidrug-resistant Staphylococcus aureus over SCSNPs at 10 μg/ml (IC 50 = 100 μg/ml).

  4. Photocatalytic Activity of Nanostructured Anatase Coatings Obtained by Cold Gas Spray

    NASA Astrophysics Data System (ADS)

    Gardon, M.; Fernández-Rodríguez, C.; Garzón Sousa, D.; Doña-Rodríguez, J. M.; Dosta, S.; Cano, I. G.; Guilemany, J. M.

    2014-10-01

    This article describes a photocatalytic nanostructured anatase coating deposited by cold gas spray (CGS) supported on titanium sub-oxide (TiO2- x ) coatings obtained by atmospheric plasma spray (APS) onto stainless steel cylinders. The photocatalytic coating was homogeneous and preserved the composition and nanostructure of the starting powder. The inner titanium sub-oxide coating favored the deposition of anatase particles in the solid state. Agglomerated nano-TiO2 particles fragmented when impacting onto the hard surface of the APS TiO2- x bond coat. The rough surface provided by APS provided an ideal scenario for entrapping the nanostructured particles, which may be adhered onto the bond coat due to chemical bonding; a possible bonding mechanism is described. Photocatalytic experiments showed that CGS nano-TiO2 coating was active for photodegrading phenol and formic acid under aqueous conditions. The results were similar to the performance obtained by competitor technologies and materials such as dip-coating P25® photocatalysts. Disparity in the final performance of the photoactive materials may have been caused by differences in grain size and the crystalline composition of titanium dioxide.

  5. Corrosion Properties of Polydopamine Coatings Formed in One-Step Immersion Process on Magnesium.

    PubMed

    Singer, Ferdinand; Schlesak, Magdalena; Mebert, Caroline; Höhn, Sarah; Virtanen, Sannakaisa

    2015-12-09

    Polydopamine layers were polymerized directly from Tris(hydroxymethyl)aminomethane-buffered solution in a one-step immersion process onto magnesium surface. Scanning electron microscopy showed successful formation of a ∼1 μm thick layer. ASTM D3359-09 "Tape test" revealed excellent adhesion of the layer. X-ray induced photoelectron spectroscopy and Fourier transform infrared spectroscopy verified the presence of polydopamine on the surface. Corrosion measurements were performed in 0.1 M NaCl solution investigating the influence of coating parameters: dopamine concentration, immersion time, solution pH, and immersion angle. Tafel analysis revealed strong improvement of corrosion behavior compared to bare magnesium. Polydopamine layers prepared with optimized coating procedure showed promising corrosion properties in Dulbecco's modified Eagle medium. In summary, polydopamine coatings offer a simple treatment for magnesium to improve the corrosion behavior and could further act as intermediate layer for further surface functionalization.

  6. Development of MnCoO Coating with New Aluminizing Process for Planar SOFC Stacks

    SciTech Connect

    Choi, Jung-Pyung; Weil, K. Scott; Chou, Y. S.; Stevenson, Jeffry W.; Yang, Zhenguo

    2011-03-22

    Low-cost, chromia-forming steels find widespread use in SOFCs at operating temperatures below 800°C, because of their low thermal expansion mismatch and low cost. However, volatile Cr-containing species originating from this scale poison the cathode material in the cells and subsequently cause power degradation in the devices. To prevent this, a conductive manganese cobaltite coating has been developed. However, this coating is not compatible with forming hermetic seals between the interconnect or window frame component and ceramic cell. This coating reacts with sealing materials. Thus, a new aluminizing process has been developed for the sealing regions in these parts, as well as for other metallic stack and balance-of-plant components. From this development, the sealing performance and SOFC stack performance became very stable.

  7. Investigation of radiation keeping property of barite coated cloth via image processing method

    SciTech Connect

    Kilincarslan, S.; Akkurt, I.; Molla, T.; Akarslan, F.

    2012-09-06

    Preservative clothes which are able to absorb radiation beam are needed not only for saving people working at radioactive environment but also for saving others from natural and man-made radiation sources we are exposed in daily life. Barite is a mineral which can be used for armour plating because of high atomic numbered element barium constituent of barite. In this study, armour plating property of barite was applied to fabrics. Barite coated fabric having characteristic of keeping radiation was obtained by penetrating barite on cloth via coating method. Radiation keeping property of fabrics obtained was determined via image processing. The results of experiments showed that barite coated fabrics have blocked radiation more than normal fabrics have done.

  8. Electromagnetic Wave Shieding Effectiveness of Carbon Fiber Sheet Coated Ferrite Film by Microwave-Hydrothermal Process

    NASA Astrophysics Data System (ADS)

    Murakami, Ri Ichi; Yamamoto, Hidetoshi; Kim, Chan Kong; Yim, Cheol Mun; Kim, Yun Hae

    The developments of electromagnetic wave shielding materials are strongly required because the malfunction of electronic equipment, mobile phone and wireless LAN avoids. In this study, it was investigated that the electromagnetic shielding effectiveness of carbon fiber sheets were enhanced by the ferrite which was coated by the microwave hydrothermal process. For coated carbon fiber sheet, the effects of ferrite and lamination of carbon fiber textile on the electromagnetic wave shielding effectiveness were discussed. In the range of frequency (100 1 GHz), the electromagnetic wave shielding effectiveness was measured by using TEM-Cell. The electromagnetic wave shielding effectiveness was greater for the coated carbon fiber sheets than for the uncoated carbon fiber sheets. When the insulation film was located between two carbon fiber sheets, the electromagnetic wave shielding effectiveness increased.

  9. Effect of Edible and Active Coating (with Rosemary and Oregano Essential Oils) on Beef Characteristics and Consumer Acceptability

    PubMed Central

    Vital, Ana Carolina Pelaes; Guerrero, Ana; Monteschio, Jessica de Oliveira; Valero, Maribel Velandia; Carvalho, Camila Barbosa; de Abreu Filho, Benício Alves; Madrona, Grasiele Scaramal; do Prado, Ivanor Nunes

    2016-01-01

    The effects of an alginate-based edible coating containing natural antioxidants (rosemary and oregano essential oils) on lipid oxidation, color preservation, water losses, texture and pH of beef steaks during 14 days of display were studied. The essential oil, edible coating and beef antioxidant activities, and beef consumer acceptability were also investigated. The edible coatings decreased lipid oxidation of the meat compared to the control. The coating with oregano was most effective (46.81% decrease in lipid oxidation) and also showed the highest antioxidant activity. The coatings significantly decreased color losses, water losses and shear force compared to the control. The coatings had a significant effect on consumer perception of odor, flavor and overall acceptance of the beef. In particular, the oregano coating showed significantly high values (approximately 7 in a 9-point scale). Active edible coatings containing natural antioxidants could improve meat product stability and therefore have potential use in the food industry. PMID:27504957

  10. 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.

  11. Antibacterial activity of cotton coated with ZnO and ZnO-CNT composites.

    PubMed

    Yazhini, K Bharathi; Prabu, H Gurumallesh

    2015-01-01

    With the growing public health awareness of the pathogenic effects and strain formations caused by microorganisms, there is an increasing need for antibacterial materials in many applications. Zinc oxide (ZnO)-1,2,3,4-butanetetracarboxylic acid (BTCA) and ZnO-BTCA-carbon nanotube (CNT) composites were synthesized by simple stirring method. The synthesized materials were coated on cotton fabric by pad-dry-cure method separately. The coated fabrics were characterized by FT-IR analysis that revealed the cross-linking in the composites. The fabrics were screened for antibacterial activity by agar well diffusion method against gram positive Staphylococcus aureus and gram negative Escherichia coli. The results showed that the ZnO-BTCA-CNT-coated fabric has improved antibacterial activity when compared with the ZnO-BTCA-coated fabric.

  12. Enhanced photoelectrochemical activity of vertically aligned ZnO-coated TiO{sub 2} nanotubes

    SciTech Connect

    Cai, Hua; Yang, Qin; You, Qinghu; Sun, Jian; Xu, Ning; Wu, Jiada; Hu, Zhigao; Duan, Zhihua

    2014-02-03

    Vertically aligned ZnO-TiO{sub 2} hetero-nanostructures constructed of anatase TiO{sub 2} nanotubes (NTs) and wurtzite ZnO coatings are fabricated by atomic layer deposition of ZnO coatings on electrochemical anodization formed TiO{sub 2} NTs, and their photoelectrochemical activities are studied through photoelectrochemical and electrochemical characterization. Compared with bare TiO{sub 2} NTs, the transient photocurrent increases to over 1.5-fold for the annealed ZnO-coated TiO{sub 2} NTs under visible illumination. The ZnO-coated TiO{sub 2} NTs also show a longer electron lifetime, a lower charge-transfer resistance and a more negative flat-band potential than the bare TiO{sub 2} NTs, confirming the improved photoelectrochemical activity due to the enhanced charge separation.

  13. Synthesis and Photocatalytic Activity of Anatase TiO2 Nanoparticles-coated Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Xie, Yi; Heo, Sung Hwan; Yoo, Seung Hwa; Ali, Ghafar; Cho, Sung Oh

    2010-03-01

    A simple and straightforward approach to prepare TiO2-coated carbon nanotubes (CNTs) is presented. Anatase TiO2 nanoparticles (NPs) with the average size ~8 nm were coated on CNTs from peroxo titanic acid (PTA) precursor even at low temperature of 100 °C. We demonstrate the effects of CNTs/TiO2 molar ratio on the adsorption capability and photocatalytic efficiency under UV-visible irradiation. The samples showed not only good optical absorption in visible range, but also great adsorption capacity for methyl orange (MO) dye molecules. These properties facilitated the great enhancement of photocatalytic activity of TiO2 NPs-coated CNTs photocatalysts. The TiO2 NPs-coated CNTs exhibited 2.45 times higher photocatalytic activity for MO degradation than that of pure TiO2.

  14. Double-layer optical fiber coating analysis in MHD flow of an elastico-viscous fluid using wet-on-wet coating process

    NASA Astrophysics Data System (ADS)

    Khan, Zeeshan; Islam, Saeed; Shah, Rehan Ali; Khan, Muhammad Altaf; Bonyah, Ebenezer; Jan, Bilal; Khan, Aurangzeb

    Modern optical fibers require a double-layer coating on the glass fiber in order to provide protection from signal attenuation and mechanical damage. The most important plastic resins used in wires and optical fibers are plastic polyvinyl chloride (PVC) and low and high density polyethylene (LDPE/HDPE), nylon and Polysulfone. One of the most important things which affect the final product after processing is the design of the coating die. In the present study, double-layer optical fiber coating is performed using melt polymer satisfying Oldroyd 8-constant fluid model in a pressure type die with the effect of magneto-hydrodynamic (MHD). Wet-on-wet coating process is applied for double-layer optical fiber coating. The coating process in the coating die is modeled as a simple two-layer Couette flow of two immiscible fluids in an annulus with an assigned pressure gradient. Based on the assumptions of fully developed laminar and MHD flow, the Oldroyd 8-constant model of non-Newtonian fluid of two immiscible resin layers is modeled. The governing nonlinear equations are solved analytically by the new technique of Optimal Homotopy Asymptotic Method (OHAM). The convergence of the series solution is established. The results are also verified by the Adomian Decomposition Method (ADM). The effect of important parameters such as magnetic parameter Mi , the dilatant constant α , the Pseodoplastic constant β , the radii ratio δ , the pressure gradient Ω , the speed of fiber optics V , and the viscosity ratio κ on the velocity profiles, thickness of coated fiber optics, volume flow rate, and shear stress on the fiber optics are investigated. At the end the result of the present work is also compared with the experimental results already available in the literature by taking non-Newtonian parameters tends to zero.

  15. Investigation of Thermal Processing on the Properties of PS304: A Solid Lubricant Coating

    NASA Technical Reports Server (NTRS)

    Benoy, Patricia A.; Williams, Syreeta (Technical Monitor)

    2002-01-01

    The effect of thermal processing on PS304, a solid lubricant coating, was investigated. PS304 is a plasma sprayed solid lubricant consisting of 10% Ag and 10% BaF2 and CaF2 in a eutectic mixture for low and high temperature lubricity respectively. In addition, PS304 contains 20% Cr2O3 for increased hardness and 60% NiCr which acts as a binder. All percents are in terms of weight not volume. Previous research on thermal processing (NAG3-2245) of PS304 revealed that substrate affected both the pre- and post-anneal hardness of the plasma spray coating. The objective of this grant was to both quantify this effect and determine whether the root cause was an artifact of the substrate or an actual difference in hardness due to interaction between the substrate and the coating. In addition to clarifying past research developments new data was sought in terms of coating growth due to annealing.

  16. Characteristics of Zinc Phosphate Coating Activated by Different Concentrations of Nickel Acetate Solution

    NASA Astrophysics Data System (ADS)

    Abdalla, Khalid; Zuhailawati, H.; Rahmat, Azmi; Azizan, A.

    2017-02-01

    Activation pretreatment with nickel acetate solution at various concentrations was performed prior to the phosphating step to enhance the corrosion resistance of carbon steel substrates. The activation solution was studied over various concentrations: 10, 50, and 100 g/L. The effects of these concentrations on surface characteristics and microstructural evolution of the coated samples were characterized by scanning electron microscopy and energy-dispersive spectroscopy. The electrochemical behavior was evaluated using potentiodynamic polarization curves, electrochemical impedance spectroscopy, and immersion test in a 3.5 pct NaCl solution. Significant increases in the nucleation sites and surface coverage of zinc phosphate coating were observed as the concentration of activation solution reached 50 g/L. The electrochemical analysis revealed that the activation treatment with 50 g/L nickel acetate solution significantly improved the protection ability of the zinc phosphate coating. The corrosion current density of activated phosphate coating with 50 g/L was reduced by 64.64 and 13.22 pct, compared to the coatings obtained with activation solutions of 10 and 100 g/L, respectively.

  17. Hygroscopic growth and droplet activation of soot particles: uncoated, succinic or sulfuric acid coated

    NASA Astrophysics Data System (ADS)

    Henning, S.; Ziese, M.; Kiselev, A.; Saathoff, H.; Möhler, O.; Mentel, T. F.; Buchholz, A.; Spindler, C.; Michaud, V.; Monier, M.; Sellegri, K.; Stratmann, F.

    2012-05-01

    The hygroscopic growth and droplet activation of uncoated soot particles and such coated with succinic acid and sulfuric acid were investigated during the IN-11 campaign at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) facility. A GFG-1000 soot generator applying either nitrogen or argon as carrier gas and a miniCAST soot generator were utilized to generate soot particles. Different organic carbon (OC) to black carbon (BC) ratios were adjusted for the CAST-soot by varying the fuel to air ratio. The hygroscopic growth was investigated by means of the mobile Leipzig Aerosol Cloud Interaction Simulator (LACIS-mobile) and two different Hygroscopicity Tandem Differential Mobility Analyzers (HTDMA, VHTDMA). Two Cloud Condensation Nucleus Counter (CCNC) were applied to measure the activation of the particles. For the untreated soot particles neither hygroscopic growth nor activation was observed at a supersaturation of 1%, with exception of a partial activation of GFG-soot generated with argon as carrier gas. Coatings of succinic acid lead to a detectable hygroscopic growth of GFG-soot and enhanced the activated fraction of GFG- (carrier gas: argon) and CAST-soot, whereas no hygroscopic growth of the coated CAST-soot was found. Sulfuric acid coatings led to an OC-content dependent hygroscopic growth of CAST-soot. Such a dependence was not observed for activation measurements. Coating with sulfuric acid decreased the amount of Polycyclic Aromatic Hydrocarbons (PAH), which were detected by AMS-measurements in the CAST-soot, and increased the amount of substances with lower molecular weight than the initial PAHs. We assume that these reaction products increased the hygroscopicity of the coated particles in addition to the coating substance itself.

  18. Hygroscopic growth and droplet activation of soot particles: uncoated, succinic or sulfuric acid coated

    NASA Astrophysics Data System (ADS)

    Henning, S.; Ziese, M.; Kiselev, A.; Saathoff, H.; Möhler, O.; Mentel, T. F.; Buchholz, A.; Spindler, C.; Michaud, V.; Monier, M.; Sellegri, K.; Stratmann, F.

    2011-10-01

    The hygroscopic growth and droplet activation of uncoated soot particles and such coated with succinic acid and sulfuric acid were investigated during the IN-11 campaign at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) facility. A GFG-1000 soot generator applying nitrogen, respectively argon as carrier gas and a miniCAST soot generator were utilized to generate soot particles. Different organic carbon (OC) to black carbon (BC) ratios were adjusted for the CAST-soot by varying the fuel to air ratio. The hygroscopic growth was investigated by means of the mobile Leipzig Aerosol Cloud Interaction Simulator (LACIS-mobile) and two different Hygroscopicity Tandem Differential Mobility Analyzers (HTDMA, VHTDMA). Two Cloud Condensation Nucleus Counter (CCNC) were applied to measure the activation of the particles. For the untreated soot particles neither hygroscopic growth nor activation was observed, with exception of a partial activation of GFG-soot generated with argon as carrier gas. Coatings of succinic acid lead to a detectable hygroscopic growth of GFG-soot and enhanced the activated fraction of GFG- (carrier gas: argon) and CAST-soot, whereas no hygroscopic growth of the coated CAST-soot was found. Sulfuric acid coatings lead to an OC-content dependent hygroscopic growth of CAST-soot. Such a dependence was not observed for activation measurements. Coating with sulfuric acid decreased the amount of Polycyclic Aromatic Hydrocarbons (PAH), which were detected by AMS-measurements in the CAST-soot, and increased the amount of substances with lower molecular weight than the initial PAHs. We assume, that these reaction products increased the hygroscopicity of the coated particles in addition to the coating substance itself.

  19. Parallel Activation in Bilingual Phonological Processing

    ERIC Educational Resources Information Center

    Lee, Su-Yeon

    2011-01-01

    In bilingual language processing, the parallel activation hypothesis suggests that bilinguals activate their two languages simultaneously during language processing. Support for the parallel activation mainly comes from studies of lexical (word-form) processing, with relatively less attention to phonological (sound) processing. According to…

  20. Unprecedented photocatalytic activity of carbon coated/MoO3 core-shell nanoheterostructurs under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Ghaffar, Iqra; Warsi, Muhammad Farooq; Shahid, Muhammad; Shakir, Imran

    2016-05-01

    We reveal that nano-scale carbon layer deposited by hydrothermal process on molybdenum oxide (MoO3) nanowires surface significantly improve the light absorption range. Furthermore, the graphene-carbon coated MoO3 nanocopmosite (rGO/C-MoO3 nanocomposite) exhibits excellent chemical stability and enhanced photocatalytic activity for methylene blue in aqueous solution under visible light irradiation compared to the bare MoO3 nanowires and carbon coated MoO3 nanowires (C-MoO3 nanowires). The enhanced photocatalytic activity of rGO/C-MoO3 nanocomposite could be attributed to the extended light absorption range, better adsorptivity of dye molecules and efficient separation of photogenerated electrons and holes. Overall, this work provides new insights that the as synthesized rGO/C-MoO3 nanocomposite can be efficiently used as high performance photocatalysts to improve the environmental protection issues under visible light irradiation.

  1. Theory of simple biochemical ``shape recognition'' via diffusion from activator coated nanoshapes

    NASA Astrophysics Data System (ADS)

    Daniels, D. R.

    2008-09-01

    Inspired by recent experiments, we model the shape sensitivity, via a typical threshold initiation response, of an underlying complex biochemical reaction network to activator coated nanoshapes. Our theory re-emphasizes that shape effects can be vitally important for the onset of functional behavior in nanopatches and nanoparticles. For certain critical or particular shapes, activator coated nanoshapes do not evoke a threshold response in a complex biochemical network setting, while for different critical or specific shapes, the threshold response is rapidly achieved. The model thus provides a general theoretical understanding for how activator coated nanoshapes can enable a chemical system to perform simple "shape recognition," with an associated "all or nothing" response. The novel and interesting cases of the chemical response due to a nanoshape that shrinks with time is additionally considered, as well as activator coated nanospheres. Possible important applications of this work include the initiation of blood clotting by nanoshapes, nanoshape effects in nanocatalysis, physiological toxicity to nanoparticles, as well as nanoshapes in nanomedicine, drug delivery, and T cell immunological response. The aim of the theory presented here is that it inspires further experimentation on simple biochemical shape recognition via diffusion from activator coated nanoshapes.

  2. Photoacoustic monitoring of water transport process in calcareous stone coated with biopolymers

    NASA Astrophysics Data System (ADS)

    May-Crespo, J.; Ortega-Morales, B. O.; Camacho-Chab, J. C.; Quintana, P.; Alvarado-Gil, J. J.; Gonzalez-García, G.; Reyes-Estebanez, M.; Chan-Bacab, M. J.

    2016-12-01

    Moisture is a critical control of chemical and physical processes leading to stone deterioration. These processes can be enhanced by microbial biofilms and associated exopolymers (EPS). There is limited current understanding of the water transport process across rocks covered by EPS. In the present work, we employed the photoacoustic technique to study the influence of three biopolymers (xanthan, microbactan and arabic gum) in the water transport process of two types of limestone rock of similar mineralogy but contrasting porosity. Both controls of RL (low porosity) and RP (high porosity) presented the higher values of water diffusion coefficient ( D) than biopolymer-coated samples, indicating that biopolymer layers slowed down the transport of water. This trend was steeper for RP samples as water was transported seven times faster than in the more porous rock. Important differences of D values were observed among samples coated by different biopolymers. Scanning electron microscopy and optical microscopy showed that surface topography was different between both types of rocks; adherence of coatings was seen predominantly in the less porous rocks samples. FTIR and NMR analysis showed the presence of pyruvate and acetate in microbactan and xanthan gum, suggesting their participation on adherence to the calcareous surfaces, sealing surface pores. These results indicate that water transport at rock interfaces is dependent on the chemistry of biopolymer and surface porosity. The implications for reduced water transport in stone conservation under the influence of biopolymers include both enhanced and lower deterioration rates along with altered efficiency of biocide treatment of epilithic biofilms.

  3. Excipient-process interactions and their impact on tablet compaction and film coating.

    PubMed

    Pandey, Preetanshu; Bindra, Dilbir S; Gour, Shruti; Trinh, Jade; Buckley, David; Badawy, Sherif

    2014-11-01

    The objective of this study was to establish the effects of the level of minor formulation components (sodium lauryl sulfate: SLS, and magnesium stearate: MgSt) and manufacturing process on final blend compaction properties and the performance of the tablets during film coating. A 2 × 2 × 3 factorial study was conducted at two levels of SLS (0% and 1%, w/w) and MgSt (0.5% and 1.75%, w/w), along with three different manufacturing processes (direct compression, high-shear wet granulation, and dry granulation). The tablets were compressed to the same solid fraction (0.9) and the resulting tablet hardness values were found to vary over a range of 13-42 SCU, highlighting large compactability differences among these batches. Increase in the level of SLS or MgSt in the formulation had a significant negative effect on compactability and the performance of film-coated tablets. The detrimental effects on compaction and coating performance were magnified for the dry granulation process, likely due to the overall increased shear experienced by excipients (SLS, MgSt, microcrystalline cellulose) during the roller compaction and milling steps. The findings of this study highlight the importance of the manufacturing process when considering the use-level of formulation components such as SLS and MgSt in the formulation.

  4. Investigation of an automated cleaning system for LMJ coating sol-gel process

    NASA Astrophysics Data System (ADS)

    Lavastre, E.; Fontaine, S.; Bergez, R.; Wender, P.; Cormont, P.; Pellegrini, C.; Beaurain, L.; Belleville, P.

    2008-09-01

    The French Commission for Atomic Energy is currently involved in a project which consists in the construction of a 2MJ/500TW (351nm) laser, so called LMJ (Megajoule-class laser) devoted to Inertial Confinement Fusion (ICF) research in France[1]. For this high power lasers, the sol-gel process[2] has been selected for 95% of laser optical coated area because of room temperature and atmospheric pressure conditions with guarantee for high optical and laser induced damage threshold (LIDT) performances at a low cost compared to conventional vacuum deposition processes. The production rate of sol-gel coatings for the LMJ optical components will require an automated cleaning surface step during sol-gel process. We are investigating a spraying system and wash cycles compatible with the two sol-gel deposition methods: dip and laminar-flow coating. The challenge is to achieve the same cleaned optical surfaces as manual process without using organic solvents. Therefore the main specifications of the cleaning quality are the following ones: a high surface energy over all optical sides (up to 400×400 mm2 area) and no degradation of polished sides (surface defects and LIDT). We present the metrologies carried out and the first results obtained from different wash cycles. These one mainly consist in measurement of contact angles, defects inspections under specific lighting conditions and LIDT tests. Several parameters of wash cycles have been investigated such as washing and rinsing temperatures, water quality, type and concentration of detergents, wettability effects...

  5. The catalytic activity of the iron-coated pumice particles used as heterogeneous catalysts in the oxidation of natural organic matter by H2O2.

    PubMed

    Alver, Alper; Karaarslan, Mihrican; Kılıç, Ahmet

    2016-08-01

    The oxidative removal of natural organic matter (NOM) from waters was investigated by hydrogen peroxide (H2O2) and iron-coated pumice particles in heterogeneous catalytic oxidation process (HCOP). Removal of trihalomethane (THM) precursors, which is formed THM by the reacts with chloride, was performed with the hydroxyl radicals. Coating the original pumice particles with iron oxides significantly enhanced the removal of NOM with peroxide. The studies were carried out in two sections: (1) decomposition of hydrogen peroxide in pure water with iron-coated pumice and (2) oxidation of THM Precursor (NOM) by hydrogen peroxide with iron-coated pumice. The monitored parameters in this study include dissolved organic carbon and trihalomethanes formation potential. The results show that iron-coated pumice catalyst significantly increased the removal efficiency of NOM in the HCOP. The results show that iron-coated pumice catalyst significantly increased the removal efficiency of NOM in the HCOP. Results show that the oxidation of NOM and remaining NOM with H2O2 is improved by the addition of iron-coated pumice particles which activate the H2O2 molecule, leading to the formation of hydroxyl radicals in a Fenton-like process.

  6. Wire rod coating process of gas diffusion layers fabrication for proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Kannan, A. M.; Sadananda, S.; Parker, D.; Munukutla, L.; Wertz, J.; Thommes, M.

    Gas diffusion layers (GDLs) were fabricated using non-woven carbon paper as a macro-porous layer substrate developed by Hollingsworth & Vose Company. A commercially viable coating process was developed using wire rod for coating micro-porous layer by a single pass. The thickness as well as carbon loading in the micro-porous layer was controlled by selecting appropriate wire thickness of the wire rod. Slurry compositions with solid loading as high as 10 wt.% using nano-chain and nano-fiber type carbons were developed using dispersion agents to provide cohesive and homogenous micro-porous layer without any mud-cracking. The surface morphology, wetting characteristics and pore size distribution of the wire rod coated GDLs were examined using FESEM, Goniometer and Hg porosimetry, respectively. The GDLs were evaluated in single cell PEMFC under various operating conditions (temperature and RH) using hydrogen and air as reactants. It was observed that the wire rod coated micro-porous layer with 10 wt.% nano-fibrous carbon based GDLs showed the highest fuel cell performance at 85 °C using H 2 and air at 50% RH, compared to all other compositions.

  7. Studies on Nanostructure Aluminium Thin Film Coatings Deposited using DC magnetron Sputtering Process

    NASA Astrophysics Data System (ADS)

    Singh M, Muralidhar; G, Vijaya; MS, Krupashankara; Sridhara, B. K.; Shridhar, T. N.

    2016-09-01

    Nanostructured thin film metallic coatings has become an area of intense research particularly in applications related solar, sensor technologies and many other optical applications such as laser windows, mirrors and reflectors. Thin film metallic coatings were deposited using DC magnetron sputtering process. The deposition rate was varied to study its influence on optical behavior of Aluminum thin films at a different argon flow rate. Studies on the optical response of these nanostructure thin film coatings were characterized using UV-VIS-NIR spectrophotometer with integrating sphere in the wavelength range of (250-2500nm) and Surface morphology were carried out using atomic force microscope with roughness ranging from 2 to 20nm and thickness was measured using Dektak measuring instrument. The reflection behavior of aluminium coatings on polycarbonate substrates has been evaluated. UV-VIS-NIR Spectrophotometer analysis indicates higher reflectance of 96% for all the films in the wavelength range of 250 nm to 2500 nm. Nano indentation study revealed that there was a considerable change in hardness values of the films prepared at different conditions.

  8. Characterisation of TiC layers deposited using an electrical discharge coating process

    NASA Astrophysics Data System (ADS)

    Algodi, S. J.; Murray, J. W.; Clare, A. T.; Brown, P. D.

    2015-10-01

    Electrical discharge machining (EDM) is a non-conventional, high-accuracy machining process for the manufacture of complex shapes, regardless of hardness of the workpiece. There is interest to develop the EDM technique for coating or surface modification by using a powder metallurgy (PM) tool electrode and/or added powder suspended within the dielectric fluid. We report on the EDM deposition of TiC coatings onto stainless steel, using either Cu or TiC electrodes, with and without Ti powder in the working oil. EDM processed layers exhibited hardness values ∼ 3-4 times higher than the substrate, emphasising the ability of EDM to impart improved mechanical performance to the surface of austenitic stainless steel.

  9. Electrochemical Study of Ni20Cr Coatings Applied by HVOF Process in ZnCl2-KCl at High Temperatures

    PubMed Central

    Porcayo-Calderón, J.; Sotelo-Mazón, O.; Casales-Diaz, M.; Ascencio-Gutierrez, J. A.; Salinas-Bravo, V. M.; Martinez-Gomez, L.

    2014-01-01

    Corrosion behavior of Ni20Cr coatings deposited by HVOF (high velocity oxygen-fuel) process was evaluated in ZnCl2-KCl (1 : 1 mole ratio) molten salts. Electrochemical techniques employed were potentiodynamic polarization curves, open circuit potential, and linear polarization resistance (LPR) measurements. Experimental conditions included static air and temperatures of 350, 400, and 450°C. 304-type SS was evaluated in the same conditions as the Ni20Cr coatings and it was used as a reference material to assess the coatings corrosion resistance. Coatings were evaluated as-deposited and with a grinded surface finished condition. Results showed that Ni20Cr coatings have a better corrosion performance than 304-type SS. Analysis showed that Ni content of the coatings improved its corrosion resistance, and the low corrosion resistance of 304 stainless steel was attributed to the low stability of Fe and Cr and their oxides in the corrosive media used. PMID:25210645

  10. Effect of additive on electrochemical corrosion properties of plasma electrolytic oxidation coatings formed on CP Ti under different processing frequency

    NASA Astrophysics Data System (ADS)

    Babaei, Mahdi; Dehghanian, Changiz; Vanaki, Mojtaba

    2015-12-01

    The plasma electrolytic oxidation (PEO) coating containing zirconium oxide was fabricated on CP Ti at different processing frequencies viz., 100 Hz and 1000 Hz in a (Na2ZrO3, Na2SiO3)-additive containing NaH2PO4-based solution, and long-term electrochemical corrosion behavior of the coatings was studied using electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl solution. Electrochemical degradation behavior of two-layered coatings formed at different frequencies was turned out to be governed by concentration of electrolyte additive. With increasing additive concentration, the coating obtained at frequency of 1000 Hz exhibited enhanced corrosion resistance. However, corrosion resistance of the coating prepared at 100 Hz was found to decrease with increased additive, which was attributed to intensified microdischarges damaging the protective effect of inner layer. Nevertheless, the electrolyte additive was found to mitigate the long-term degradation of the coatings to a significant extent.

  11. Plasma electrolytic oxide coatings on valve metals and their activity in CO oxidation

    NASA Astrophysics Data System (ADS)

    Lukiyanchuk, I. V.; Rudnev, V. S.; Tyrina, L. M.; Chernykh, I. V.

    2014-10-01

    Two approaches have been examined for obtaining titanium- or aluminum-supported catalysts with transition and noble metals using the plasma electrolytic oxidation (PEO) technique. Elemental compositions, distribution of active elements and catalytic activity in CO oxidation have been compared for composites formed by one-stage PEO technique and those obtained as a result of modification of PEO coatings by impregnation.

  12. Self-Lubricating Coatings for Elevated Temperature Applications Using A High-Velocity-Particle-Consolidation (HVPC) Process

    DTIC Science & Technology

    2008-12-01

    process can be used for the development of Ni-BN composite coatings with comparable hardness and adhesive strengths relative to Ni coatings...56 3.5.4 Adhesion Testing..................................................................................57 3.5.5 Fretting Wear...57 Figure 3.11: Samples tested for adhesion

  13. Formation Mechanisms, Structure, and Properties of HVOF-Sprayed WC-CoCr Coatings: An Approach Toward Process Maps

    NASA Astrophysics Data System (ADS)

    Varis, T.; Suhonen, T.; Ghabchi, A.; Valarezo, A.; Sampath, S.; Liu, X.; Hannula, S.-P.

    2014-08-01

    Our study focuses on understanding the damage tolerance and performance reliability of WC-CoCr coatings. In this paper, the formation of HVOF-sprayed tungsten carbide-based cermet coatings is studied through an integrated strategy: First-order process maps are created by using online-diagnostics to assess particle states in relation to process conditions. Coating properties such as hardness, wear resistance, elastic modulus, residual stress, and fracture toughness are discussed with a goal to establish a linkage between properties and particle characteristics via second-order process maps. A strong influence of particle state on the mechanical properties, wear resistance, and residual stress stage of the coating was observed. Within the used processing window (particle temperature ranged from 1687 to 1831 °C and particle velocity from 577 to 621 m/s), the coating hardness varied from 1021 to 1507 HV and modulus from 257 to 322 GPa. The variation in coating mechanical state is suggested to relate to the microstructural changes arising from carbide dissolution, which affects the properties of the matrix and, on the other hand, cohesive properties of the lamella. The complete tracking of the coating particle state and its linking to mechanical properties and residual stresses enables coating design with desired properties.

  14. Osteoconductivity and Hydrophilicity of TiO(2) Coatings on Ti Substrates Prepared by Different Oxidizing Processes.

    PubMed

    Yamamoto, Dai; Kawai, Ikki; Kuroda, Kensuke; Ichino, Ryoichi; Okido, Masazumi; Seki, Azusa

    2012-01-01

    Various techniques for forming TiO(2) coatings on Ti have been investigated for the improvement of the osteoconductivity of Ti implants. However, it is not clear how the oxidizing process affects this osteoconductivity. In this study, TiO(2) coatings were prepared using the following three processes: anodizing in 0.1 M H(3)PO(4) or 0.1 M NaOH aqueous solution; thermal oxidation at 673 K for 2 h in air; and a two-step process of anodizing followed by thermal oxidation. The oxide coatings were evaluated using SEM, XRD, and XPS. The water contact angle on the TiO(2) coatings was measured as a surface property. The osteoconductivity of these samples was evaluated by measuring the contact ratio of formed hard tissue on the implanted samples (defined as the R(B-I) value) after 14 d implantation in rats' tibias. Anatase was formed by anodizing and rutile by thermal oxidation, but the difference in the TiO(2) crystal structure did not influence the osteoconductivity. Anodized TiO(2) coatings were hydrophilic, but thermally oxidized TiO(2) coatings were less hydrophilic than anodized TiO(2) coatings because they lacked in surface OH groups. The TiO(2) coating process using anodizing without thermal oxidation gave effective improvement of the osteoconductivity of Ti samples.

  15. Osteoconductivity and Hydrophilicity of TiO2 Coatings on Ti Substrates Prepared by Different Oxidizing Processes

    PubMed Central

    Yamamoto, Dai; Kawai, Ikki; Kuroda, Kensuke; Ichino, Ryoichi; Okido, Masazumi; Seki, Azusa

    2012-01-01

    Various techniques for forming TiO2 coatings on Ti have been investigated for the improvement of the osteoconductivity of Ti implants. However, it is not clear how the oxidizing process affects this osteoconductivity. In this study, TiO2 coatings were prepared using the following three processes: anodizing in 0.1 M H3PO4 or 0.1 M NaOH aqueous solution; thermal oxidation at 673 K for 2 h in air; and a two-step process of anodizing followed by thermal oxidation. The oxide coatings were evaluated using SEM, XRD, and XPS. The water contact angle on the TiO2 coatings was measured as a surface property. The osteoconductivity of these samples was evaluated by measuring the contact ratio of formed hard tissue on the implanted samples (defined as the RB-I value) after 14 d implantation in rats' tibias. Anatase was formed by anodizing and rutile by thermal oxidation, but the difference in the TiO2 crystal structure did not influence the osteoconductivity. Anodized TiO2 coatings were hydrophilic, but thermally oxidized TiO2 coatings were less hydrophilic than anodized TiO2 coatings because they lacked in surface OH groups. The TiO2 coating process using anodizing without thermal oxidation gave effective improvement of the osteoconductivity of Ti samples. PMID:23316128

  16. Biological and immunotoxicity evaluation of antimicrobial peptide-loaded coatings using a layer-by-layer process on titanium

    PubMed Central

    Shi, Jue; Liu, Yu; Wang, Ying; Zhang, Jing; Zhao, Shifang; Yang, Guoli

    2015-01-01

    The prevention and control of peri-implantitis is a challenge in dental implant surgery. Dental implants with sustained antimicrobial coating are an ideal way of preventing peri-implantitis. This study reports development of a non- immunotoxicity multilayered coating on a titanium surface that had sustained antimicrobial activity and limited early biofilm formation. In this study, the broad spectrum AMP, Tet213, was linked to collagen IV through sulfo-SMPB and has been renamed as AMPCol. The multilayer AMPCol coatings were assembled on smooth titanium surfaces using a LBL technique. Using XPS, AFM, contact angle analysis, and QCM, layer-by-layer accumulation of coating thickness was measured and increased surface wetting compared to controls was confirmed. Non-cytotoxicity to HaCaT and low erythrocyte hemolysis by the AMPCol coatings was observed. In vivo immunotoxicity assays showed IP administration of AMPCol did not effect serum immunoglobulin levels. This coating with controlled release of AMP decreased the growth of both a Gram-positive aerobe (Staphylococcus aureus) and a Gram-negative anaerobe (Porphyromonas gingivalis) up to one month. Early S. aureus biofilm formation was inhibited by the coating. The excellent long-term sustained antimicrobial activity of this multilayer coating is a potential method for preventing peri-implantitis through coated on the neck of implants before surgery. PMID:26548760

  17. Biological and immunotoxicity evaluation of antimicrobial peptide-loaded coatings using a layer-by-layer process on titanium.

    PubMed

    Shi, Jue; Liu, Yu; Wang, Ying; Zhang, Jing; Zhao, Shifang; Yang, Guoli

    2015-11-09

    The prevention and control of peri-implantitis is a challenge in dental implant surgery. Dental implants with sustained antimicrobial coating are an ideal way of preventing peri-implantitis. This study reports development of a non- immunotoxicity multilayered coating on a titanium surface that had sustained antimicrobial activity and limited early biofilm formation. In this study, the broad spectrum AMP, Tet213, was linked to collagen IV through sulfo-SMPB and has been renamed as AMPCol. The multilayer AMPCol coatings were assembled on smooth titanium surfaces using a LBL technique. Using XPS, AFM, contact angle analysis, and QCM, layer-by-layer accumulation of coating thickness was measured and increased surface wetting compared to controls was confirmed. Non-cytotoxicity to HaCaT and low erythrocyte hemolysis by the AMPCol coatings was observed. In vivo immunotoxicity assays showed IP administration of AMPCol did not effect serum immunoglobulin levels. This coating with controlled release of AMP decreased the growth of both a Gram-positive aerobe (Staphylococcus aureus) and a Gram-negative anaerobe (Porphyromonas gingivalis) up to one month. Early S. aureus biofilm formation was inhibited by the coating. The excellent long-term sustained antimicrobial activity of this multilayer coating is a potential method for preventing peri-implantitis through coated on the neck of implants before surgery.

  18. Biological and immunotoxicity evaluation of antimicrobial peptide-loaded coatings using a layer-by-layer process on titanium

    NASA Astrophysics Data System (ADS)

    Shi, Jue; Liu, Yu; Wang, Ying; Zhang, Jing; Zhao, Shifang; Yang, Guoli

    2015-11-01

    The prevention and control of peri-implantitis is a challenge in dental implant surgery. Dental implants with sustained antimicrobial coating are an ideal way of preventing peri-implantitis. This study reports development of a non- immunotoxicity multilayered coating on a titanium surface that had sustained antimicrobial activity and limited early biofilm formation. In this study, the broad spectrum AMP, Tet213, was linked to collagen IV through sulfo-SMPB and has been renamed as AMPCol. The multilayer AMPCol coatings were assembled on smooth titanium surfaces using a LBL technique. Using XPS, AFM, contact angle analysis, and QCM, layer-by-layer accumulation of coating thickness was measured and increased surface wetting compared to controls was confirmed. Non-cytotoxicity to HaCaT and low erythrocyte hemolysis by the AMPCol coatings was observed. In vivo immunotoxicity assays showed IP administration of AMPCol did not effect serum immunoglobulin levels. This coating with controlled release of AMP decreased the growth of both a Gram-positive aerobe (Staphylococcus aureus) and a Gram-negative anaerobe (Porphyromonas gingivalis) up to one month. Early S. aureus biofilm formation was inhibited by the coating. The excellent long-term sustained antimicrobial activity of this multilayer coating is a potential method for preventing peri-implantitis through coated on the neck of implants before surgery.

  19. A novel, polymer-coated oncolytic measles virus overcomes immune suppression and induces robust antitumor activity

    PubMed Central

    Nosaki, Kaname; Hamada, Katsuyuki; Takashima, Yuto; Sagara, Miyako; Matsumura, Yumiko; Miyamoto, Shohei; Hijikata, Yasuki; Okazaki, Toshihiko; Nakanishi, Yoichi; Tani, Kenzaburo

    2016-01-01

    Although various therapies are available to treat cancers, including surgery, chemotherapy, and radiotherapy, cancer has been the leading cause of death in Japan for the last 30 years, and new therapeutic modalities are urgently needed. As a new modality, there has recently been great interest in oncolytic virotherapy, with measles virus being a candidate virus expected to show strong antitumor effects. The efficacy of virotherapy, however, was strongly limited by the host immune response in previous clinical trials. To enhance and prolong the antitumor activity of virotherapy, we combined the use of two newly developed tools: the genetically engineered measles virus (MV-NPL) and the multilayer virus-coating method of layer-by-layer deposition of ionic polymers. We compared the oncolytic effects of this polymer-coated MV-NPL with the naked MV-NPL, both in vitro and in vivo. In the presence of anti-MV neutralizing antibodies, the polymer-coated virus showed more enhanced oncolytic activity than did the naked MV-NPL in vitro. We also examined antitumor activities in virus-treated mice. Complement-dependent cytotoxicity and antitumor activities were higher in mice treated with polymer-coated MV-NPL than in mice treated with the naked virus. This novel, polymer-coated MV-NPL is promising for clinical cancer therapy in the future. PMID:27847861

  20. A novel, polymer-coated oncolytic measles virus overcomes immune suppression and induces robust antitumor activity.

    PubMed

    Nosaki, Kaname; Hamada, Katsuyuki; Takashima, Yuto; Sagara, Miyako; Matsumura, Yumiko; Miyamoto, Shohei; Hijikata, Yasuki; Okazaki, Toshihiko; Nakanishi, Yoichi; Tani, Kenzaburo

    2016-01-01

    Although various therapies are available to treat cancers, including surgery, chemotherapy, and radiotherapy, cancer has been the leading cause of death in Japan for the last 30 years, and new therapeutic modalities are urgently needed. As a new modality, there has recently been great interest in oncolytic virotherapy, with measles virus being a candidate virus expected to show strong antitumor effects. The efficacy of virotherapy, however, was strongly limited by the host immune response in previous clinical trials. To enhance and prolong the antitumor activity of virotherapy, we combined the use of two newly developed tools: the genetically engineered measles virus (MV-NPL) and the multilayer virus-coating method of layer-by-layer deposition of ionic polymers. We compared the oncolytic effects of this polymer-coated MV-NPL with the naked MV-NPL, both in vitro and in vivo. In the presence of anti-MV neutralizing antibodies, the polymer-coated virus showed more enhanced oncolytic activity than did the naked MV-NPL in vitro. We also examined antitumor activities in virus-treated mice. Complement-dependent cytotoxicity and antitumor activities were higher in mice treated with polymer-coated MV-NPL than in mice treated with the naked virus. This novel, polymer-coated MV-NPL is promising for clinical cancer therapy in the future.

  1. Processing, properties and applications of composites using powder-coated epoxy towpreg technology

    NASA Technical Reports Server (NTRS)

    Bayha, T. D.; Osborne, P. P.; Thrasher, T. P.; Hartness, J. T.; Johnston, N. J.; Marchello, J. M.; Hugh, M. K.

    1993-01-01

    Composite manufacturing using the current prepregging technology of impregnating liquid resin into three-dimensionally reinforced textile preforms can be a costly and difficult operation. Alternatively, using polymer in the solid form, grinding it into a powder, and then depositing it onto a carbon fiber tow prior to making a textile preform is a viable method for the production of complex textile shapes. The powder-coated towpreg yarn is stable, needs no refrigeration, contains no solvents and is easy to process into various woven and braided preforms for later consolidation into composite structures. NASA's Advanced Composites Technology (ACT) program has provided an avenue for developing the technology by which advanced resins and their powder-coated preforms may be used in aircraft structures. Two-dimensional braiding and weaving studies using powder-coated towpreg have been conducted to determine the effect of resin content, towpreg size and twist on textile composite properties. Studies have been made to customize the towpreg to reduce friction and bulk factor. Processing parameters have been determined for three epoxy resin systems on eight-harness satin fabric, and on more advanced 3-D preform architectures for the downselected resin system. Processing effects and the resultant mechanical properties of these textile composites will be presented and compared.

  2. Fourier-transform spectral interferometry for in situ group delay dispersion monitoring of thin film coating processes.

    PubMed

    Schlichting, Sebastian; Willemsen, Thomas; Ehlers, Henrik; Morgner, Uwe; Ristau, Detlev

    2016-10-03

    A fast Fourier-based measurement system to determine phase, group delay, and group delay dispersion during optical coating processes is proposed. The in situ method is based on a Michelson interferometer with a broad band light source and a very fast spectrometer. To our knowledge, group delay dispersion measurements directly on the moving substrates during a deposition process for complex interference coatings have been demonstrated for the first time. Especially for the very precise production of chirped mirrors it is advantageous to get information about the phase properties of the grown layer stack to react on errors and retrieve more information about the coating process.

  3. Characterization of Fe–Cr alloy metallic interconnects coated with LSMO using the aerosol deposition process

    SciTech Connect

    Huang, Jian-Jia; Fu, Yen-Pei; Wang, Jian-Yih; Cheng, Yung-Neng; Lee, Shyong; Hsu, Jin-Cherng

    2014-03-01

    Graphical abstract: - Highlights: • Lanthanum strontium manganite (LSMO) as the protective layer for metallic interconnects was successfully prepared by aerosol deposition method (AD). • The microstructure, electrical resistance and composition for LSMO-coated Fe–Cr alloys undergoing high temperature, long-hour oxidation were investigated. • The denser protective layer prepared by AD might effectively prohibit the growth of oxidized scale after long time running at 800 °C in air. - Abstract: A Fe–Cr alloy, used for metallic interconnects, was coated with a protective layer of lanthanum strontium manganite (LSMO) using the aerosol deposition method (AD). The effects of the LSMO protective layer, which was coated on the Fe–Cr interconnects using AD, on the area specific resistance (ASR) during high temperature oxidation and the Cr evaporation behaviors were systematically investigated in this paper. The microstructures, morphologies, and compositions of the oxidized scales that appeared on the LSMO-coated Fe–Cr alloy after annealing at 800 °C for 750 h in air were examined using SEM equipped with EDS. The EPMA mapping of the LSMO-coated Fe–Cr interconnects undergoing long term, high-temperature oxidation was used to explain the formation layers of the oxidized scale, which consists of (Mn,Cr){sub 3}O{sub 4} and Cr{sub 2}O{sub 3} layers. Moreover, the experimental results revealed that the AD process is a potential method for preparing denser protective layers with highly desirable electrical properties for metallic interconnects.

  4. Coatings for protection of equipment for biochemical processing of geothermal residues: Progress report FY`97

    SciTech Connect

    Allan, M.L.

    1997-11-01

    Thermal sprayed ethylene methacrylic acid (EMAA) and ethylene tetrafluoroethylene (ETFE), spray-and-bake ETFE and polyvinylidene fluoride (PVDF) and brushable ceramic-epoxy coatings were evaluated for corrosion protection in a biochemical process to treat geothermal residues. Coupon, Atlas cell, peel strength, cathodic disbondment and abrasion tests were performed in aggressive environments including geothermal sludge, hypersaline brine and sulfur-oxidizing bacteria (Thiobacillus ferrooxidans) to determine suitability for protecting storage tanks and reaction vessels. It was found that all of the coatings were resistant to chemical attack and biodegradation at the test temperature of 55 C. The EMAA coatings protected 316L stainless steel from corrosion in coupon tests. However, corrosion of mild steel substrates thermal sprayed with EMAA and ETFE occurred in Atlas cell tests that simulated a lined reactor operating environment and this resulted in decreased adhesive strength. Peel tests to measure residual adhesion revealed that failure mode was dependent on exposure conditions. Abrasion tests showed that the ceramic-epoxy had good resistance to the abrasive effects of sludge. Thermal sprayed EMAA coatings also displayed abrasion resistance. Cathodic disbondment tests in brine at room temperature indicated that EMAA coatings are resistant to disbondment at applied potentials of {minus}780 to {minus}1,070 mV SCE for the test conditions and duration. Slight disbondment of one specimen occurred at a potential of {minus}1,500 mV SCE. The EMAA may be suited to use in conjunction with cathodic protection although further long-term, higher temperature testing would be needed.

  5. Influence of process parameters on the content of biomimetic calcium phosphate coating on titanium: a Taguchi analysis.

    PubMed

    Thammarakcharoen, Faungchat; Suvannapruk, Waraporn; Suwanprateeb, Jintamai

    2014-10-01

    In this study, a statistical design of experimental methodology based on Taguchi orthogonal design has been used to study the effect of various processing parameters on the amount of calcium phosphate coating produced by such technique. Seven control factors with three levels each including sodium hydroxide concentration, pretreatment temperature, pretreatment time, cleaning method, coating time, coating temperature and surface area to solution volume ratio were studied. X-ray diffraction revealed that all the coatings consisted of the mixture of octacalcium phosphate (OCP) and hydroxyapatite (HA) and the presence of each phase depended on the process conditions used. Various content and size (-1-100 μm) of isolated spheroid particles with nanosized plate-like morphology deposited on the titanium surface or a continuous layer of plate-like nanocrystals having the plate thickness in the range of -100-300 nm and the plate width in the range of 3-8 μm were formed depending on the process conditions employed. The optimum condition of using sodium hydroxide concentration of 1 M, pretreatment temperature of 70 degrees C, pretreatment time of 24 h, cleaning by ultrasonic, coating time of 6 h, coating temperature of 50 degrees C and surface area to solution volume ratio of 32.74 for producing the greatest amount of the coating formed on the titanium surface was predicted and validated. In addition, coating temperature was found to be the dominant factor with the greatest contribution to the coating formation while coating time and cleaning method were significant factors. Other factors had negligible effects on the coating performance.

  6. Modification of granular activated carbon surface by chitosan coating for geosmin removal: sorption performances.

    PubMed

    Vinitnantharat, S; Rattanasirisophon, W; Ishibashi, Y

    2007-01-01

    This study presents the results of the sorption performances for geosmin removal by sorption onto granular activated carbons (GAC) manufactured from different raw materials of coconut shell and bituminous coal. The surface of GAC was modified by chitosan coating. The 90% deacetylated chitosan flakes were used for coating on GAC with the GAC: chitosan ratio of 5:1. The surface of GAC was characterised by scanning electron microscope (SEM) analysis, Fourier transform infrared spectroscopy and measurement of the pH solution of GAC samples. The sorption of geosmin onto the chitosan for both uncoated and coated GACs could be described by the Freundlich adsorption model. Data revealed that the sequence of Freundlich constant (K(F)) was chitosan coated bitominous coal (CB) > uncoated bituminous coal (UB) > chitos approximately equal to an coated coconut shell (CC) approximately equal to uncoated coconut shell (UC). The bituminous coal based GAC with chitosan coating had a maximum capacity of 23.57 microg/g which was approximately two-fold of uncoated bituminous coal based GAC. Two simplified kinetic models, pseudo-first order and pseudo-second order, were tested to investigate the sorption mechanisms. It was found that the intraparticle diffusion was a rate controlling step for the sorption and followed the pseudo-second order equation.

  7. Electrodeposition, characterization, and antibacterial activity of zinc/silver particle composite coatings

    NASA Astrophysics Data System (ADS)

    Reyes-Vidal, Y.; Suarez-Rojas, R.; Ruiz, C.; Torres, J.; Ţălu, Ştefan; Méndez, Alia; Trejo, G.

    2015-07-01

    Composite coatings consisting of zinc and silver particles (Zn/AgPs) with antibacterial activity were prepared using an electrodeposition technique. The morphology, composition, and structure of the Zn/AgPs composite coatings were analyzed using scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), inductively coupled plasma (ICP) spectrometry, and X-ray diffraction (XRD). The antibacterial properties of the coatings against the microorganisms Escherichia coli as a model Gram-negative bacterium and Staphylococcus aureus as a model Gram-positive bacterium were studied quantitatively and qualitatively. The results revealed that the dispersant cetyltrimethylammonium bromide (CTAB) assisted in the formation of a stable suspension of Ag particles in the electrolytic bath for 24 h. Likewise, a high concentration of CTAB in the electrolytic bath promoted an increase in the number of Ag particles occluded in the Zn/AgPs coatings. The Zn/AgPs coatings that were obtained were compact, smooth, and shiny materials. Antimicrobial tests performed on the Zn/AgPs coatings revealed that the inhibition of bacterial growth after 30 min of contact time was between 91% and 98% when the AgPs content ranged from 4.3 to 14.0 mg cm-3.

  8. Kinetics of the drying process of an anti-adherent coating using Photothermal Radiometry and Micro-Raman

    NASA Astrophysics Data System (ADS)

    Hurtado-Castañeda, D. M.; Fernández, J.; Velázquez, R.; Estévez, M.; Vargas, S.; Rodríguez, R.; Rodríguez, M. E.

    2005-06-01

    The kinetics of the drying process of a new anti-adherent (anti-graffiti) polymeric coating containing organic solvent was determined using Photothermal Radiometry (PTR) and Micro-Raman (μ-R) Spectroscopy. PTR Spectroscopy was used to study, in real time, the kinetics of the drying process in samples protected with coatings with and without anti-adherent molecules. These were applied on a metal and silicon substrates. The PTR spectrum for coating without anti-adherent, shows a single relaxation time, while for coating containing anti-adherent shows two relaxation times corresponding to two different mechanisms: the solvent evaporation and the molecular re-arrangements of the two different molecular species present in the coating; the kinetic of the solvent evaporation is strongly dependent, as expected, on the solvent concentration.

  9. Elastoplastic analysis of process induced residual stresses in thermally sprayed coatings

    SciTech Connect

    Chen Yongxiong; Liang Xiubing; Liu Yan; Xu Binshi

    2010-07-15

    The residual stresses induced from thermal spraying process have been extensively investigated in previous studies. However, most of such works were focused on the elastic deformation range. In this paper, an elastoplastic model for predicting the residual stresses in thermally sprayed coatings was developed, in which two main contributions were considered, namely the deposition induced stress and that due to differential thermal contraction between the substrate and coating during cooling. The deposition induced stress was analyzed based on the assumption that the coating is formed layer-by-layer, and then a misfit strain is accommodated within the multilayer structure after the addition of each layer (plastic deformation is induced consequently). From a knowledge of specimen dimensions, processing temperatures, and material properties, residual stress distributions within the structure can be determined by implementing the model with a simple computer program. A case study for the plasma sprayed NiCoCrAlY on Inconel 718 system was performed finally. Besides some similar phenomena observed from the present study as compared with previous elastic model reported in literature, the elastoplastic model also provides some interesting features for prediction of the residual stresses.

  10. Highly Segmented Thermal Barrier Coatings Deposited by Suspension Plasma Spray: Effects of Spray Process on Microstructure

    NASA Astrophysics Data System (ADS)

    Chen, Xiaolong; Honda, Hiroshi; Kuroda, Seiji; Araki, Hiroshi; Murakami, Hideyuki; Watanabe, Makoto; Sakka, Yoshio

    2016-12-01

    Effects of the ceramic powder size used for suspension as well as several processing parameters in suspension plasma spraying of YSZ were investigated experimentally, aiming to fabricate highly segmented microstructures for thermal barrier coating (TBC) applications. Particle image velocimetry (PIV) was used to observe the atomization process and the velocity distribution of atomized droplets and ceramic particles travelling toward the substrates. The tested parameters included the secondary plasma gas (He versus H2), suspension injection flow rate, and substrate surface roughness. Results indicated that a plasma jet with a relatively higher content of He or H2 as the secondary plasma gas was critical to produce highly segmented YSZ TBCs with a crack density up to 12 cracks/mm. The optimized suspension flow rate played an important role to realize coatings with a reduced porosity level and improved adhesion. An increased powder size and higher operation power level were beneficial for the formation of highly segmented coatings onto substrates with a wider range of surface roughness.

  11. Process-directed self-assembly of multiblock copolymers: Solvent casting vs spray coating

    NASA Astrophysics Data System (ADS)

    Tang, Q.; Tang, J.; Müller, M.

    2016-10-01

    Using computer simulation of a soft, coarse-grained model and self-consistent field theory we investigate how collapsed, globular chain conformations in the initial stages of structure formation, which are produced by spray-coating, affect the single-chain structure and morphology of microphase-separated multiblock copolymers. Comparing spray-coated films with films that start from a disordered state of Gaussian chains, we observe that the collapsed molecular conformations in the initial stage give rise to (1) a smaller fraction of blocks that straddle domains (bridges), (2) a significant reduction of the molecular extension normal to the internal interfaces, and (3) a slightly larger lamellar domain spacing in the final morphology. The relaxation of molecular conformations towards equilibrium is very protracted for both processes - solvent casting and spray coating. These findings illustrate that the process conditions of the copolymer materials may significantly affect materials properties (such as mechanical properties) because the system does not reach thermal equilibrium on the relevant time scales.

  12. Electrochemical characterization of YSZ thick films deposited by dip-coating process

    NASA Astrophysics Data System (ADS)

    Mauvy, F.; Lenormand, P.; Lalanne, C.; Ansart, F.; Bassat, J. M.; Grenier, J. C.; Groupement de Recherches Cnrs "Pacte", Gdr 2985

    Yttria stabilized zirconia (YSZ, 8% Y 2O 3) thick films were coated on dense alumina substrates by a dip-coating process. The suspension was obtained by addition of a polymeric matrix in a stable suspension of commercial YSZ (Tosoh) powders dispersed in an azeotropic mixture MEK-EtOH. The suspension composition was improved by the addition of YSZ Tosoh particles encapsulated by zirconium alkoxide sol containing yttrium nitrate which are the precursors of the 8-YSZ oxide. This optimal formulation allowed preparing, via a dip-coating process, thick films which were, after thermal treatment, homogeneous, dense and crack-free. A specific method was performed to measure the electrical conductivity, i.e. to determine the ionic conductivity of the film: it uses the four-point probe technique combined with ac impedance spectroscopy. The good agreement between the classical two-electrode measurements performed on YSZ pellets and the four-electrode ones performed on YSZ films allows concluding that this method is relevant for characterizing the transport properties of thick films.

  13. Silicanizing Process On Mild Steel Substrate by Using Tronoh Silica Sand: Microstructure, composition and coating growth

    NASA Astrophysics Data System (ADS)

    Y, Yusnenti F. M.; M, Othman; Mustapha, Mazli; I, MohdYusri

    2016-02-01

    A new Silicanizing process on formation of coating on mild steel using Tronoh Silica Sand (TSS) is presented. The process was performed in the temperature range 1000- 1100°C and with varying deposition time of 1-4 hours. Influence of the layer and the substrate constituents on the coating compatibility of the whole silicanized layer is described in detail. Morphology and structure of the silicanized layer were investigated by XRF, XRD and SEM. It is observed that diffusion coatings containing high concentrations of silica which profile distribution of SiO2 in the silicanized layer was encountered and the depth from the surface to the substrate was taken as the layer thickness. The results also depicted that a longer deposition time have tendency to produce a looser and larger grain a hence rougher layer. The silicanized layer composed of FeSi and Fe2SiO4 phases with preferred orientation within the experimental range. It is also found that longer deposition time and higher temperature resulted in an increase in SiO2 concentration on the substrate (mild steel).

  14. Bubbles versus biofilms: a novel method for the removal of marine biofilms attached on antifouling coatings using an ultrasonically activated water stream

    NASA Astrophysics Data System (ADS)

    Salta, M.; Goodes, L. R.; Maas, B. J.; Dennington, S. P.; Secker, T. J.; Leighton, T. G.

    2016-09-01

    The accumulation of marine organisms on a range of manmade surfaces, termed biofouling, has proven to be the Achilles’ heel of the shipping industry. Current antifouling coatings, such as foul release coatings (FRCs), only partially inhibit biofouling, since biofilms remain a major issue. Mechanical ship hull cleaning is commonly employed to remove biofilms, but these methods tend to damage the antifouling coating and often do not result in full removal. Here, we report the effectiveness of biofilm removal from FRCs through a novel cleaning device that uses an ultrasonically activated stream (UAS). In this device, ultrasound enhances the cleaning properties of microbubbles in a freely flowing stream of water. The UAS was applied on two types of commercial FRCs which were covered with biofilm growth following twelve days immersion in the marine environment. Biofilm removal was quantified in terms of reduction in biovolume and surface roughness, both measured using an optical profilometer, which were then compared with similar measurements after cleaning with a non-ultrasonically activated water stream. It was found that the UAS significantly improves the cleaning capabilities of a water flow, up to the point where no detectable biofilm remained on the coating surfaces. Overall biofilm surface coverage was significantly lower on the FRC coatings cleaned with the UAS system when compared to the coatings cleaned with water or not cleaned at all. When biofilm biomass removal was investigated, the UAS system resulted in significantly lower biovolume values even when compared to the water cleaning treatment with biovolume values close to zero. Remarkably, the surface roughness of the coatings after cleaning with the UAS was found to be comparable to that of the blank, non-immersed coatings, illustrating that the UAS did not damage the coatings in the process. The data supporting this study are openly available from the University of Southampton repository at http

  15. Development, Processing, and Testing of High-Performance Corrosion-Resistant HVOF Coatings

    SciTech Connect

    Farmer, J; Wong, F; Haslam, J; Estill, J; Branagan, D; Yang, N; Blue, C

    2003-08-26

    New amorphous-metal and ceramic coatings applied by the high-velocity oxy-fuel (HVOF) process may reduce the waste package materials cost of the Yucca Mountain high-level nuclear waste repository by over $4 billion (cost reduction of 27 to 42%). Two critical requirements that have been determined from design analysis are protection in brines that may evolve from the evaporative concentration of pore waters and protection for waste package welds, thereby preventing exposure to environments that might cause stress corrosion cracking (SCC). Our efforts are directed towards producing and evaluating these high-performance coatings for the development of lower cost waste packages, and will leverage a cost-effective collaboration with DARPA for applications involving marine corrosion.

  16. Influence Of Tool Geometry, Tool Coating And Process Parameters In Thixoextrusion Of Steel

    SciTech Connect

    Knauf, Frederik; Hirt, Gerhard; Immich, Philipp; Bobzin, Kirsten

    2007-04-07

    Thixoextrusion could become one possibility to enlarge the complexity of extruded profiles made of steel. Accordingly semi-solid extrusion experiments of X210CrW12 tool steel using round dies of approximately 15 mm diameter were performed in order to achieve first information concerning possible process windows and process limits. For liquid fractions between 38% and 10%, extrusion press velocities from 10 mm/s to 50 mm/s and dies with novel PVD-coatings no complete solidification during extrusion was achieved. However the collected pieces of the extruded bars showed a fine and evenly distributed globular microstructure.

  17. 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

  18. Spin-coating process evolution and reproducibility for power-law fluids.

    PubMed

    Jardim, P L G; Michels, A F; Horowitz, F

    2014-03-20

    A distinct development of an exact analytical solution for power-law fluids during the spin-coating process is presented for temporal and spatial thickness evolution, after steady state conditions are attained. This solution leads to the definition of a characteristic time, related to the memory of the initial thickness profile. Previously obtained experimental data, for several rotation speeds and carboxymetilcellulose concentrations in water, are quantitatively analyzed through the evaluation of their characteristic times and compared with theoretical predictions, thus allowing better understanding of thickness profile evolution and of process reproducibility.

  19. Solution processable broadband transparent mixed metal oxide nanofilm optical coatings via substrate diffusion doping

    NASA Astrophysics Data System (ADS)

    Glynn, Colm; Aureau, Damien; Collins, Gillian; O'Hanlon, Sally; Etcheberry, Arnaud; O'Dwyer, Colm

    2015-11-01

    Devices composed of transparent materials, particularly those utilizing metal oxides, are of significant interest due to increased demand from industry for higher fidelity transparent thin film transistors, photovoltaics and a myriad of other optoelectronic devices and optics that require more cost-effective and simplified processing techniques for functional oxides and coatings. Here, we report a facile solution processed technique for the formation of a transparent thin film through an inter-diffusion process involving substrate dopant species at a range of low annealing temperatures compatible with processing conditions required by many state-of-the-art devices. The inter-diffusion process facilitates the movement of Si, Na and O species from the substrate into the as-deposited vanadium oxide thin film forming a composite fully transparent V0.0352O0.547Si0.4078Na0.01. Thin film X-ray diffraction and Raman scattering spectroscopy show the crystalline component of the structure to be α-NaVO3 within a glassy matrix. This optical coating exhibits high broadband transparency, exceeding 90-97% absolute transmission across the UV-to-NIR spectral range, while having low roughness and free of surface defects and pinholes. The production of transparent films for advanced optoelectronic devices, optical coatings, and low- or high-k oxides is important for planar or complex shaped optics or surfaces. It provides opportunities for doping metal oxides to ternary, quaternary or other mixed metal oxides on glass, encapsulants or other substrates that facilitate diffusional movement of dopant species.Devices composed of transparent materials, particularly those utilizing metal oxides, are of significant interest due to increased demand from industry for higher fidelity transparent thin film transistors, photovoltaics and a myriad of other optoelectronic devices and optics that require more cost-effective and simplified processing techniques for functional oxides and coatings

  20. Sensitive fluorimetric assays for α-glucosidase activity and inhibitor screening based on β-cyclodextrin-coated quantum dots.

    PubMed

    Liu, Si-Yao; Wang, Huan; He, Tian; Qi, Liang; Zhang, Zhi-Qi

    2016-02-01

    A fluorescence method was established for a α-glucosidase activity assay and inhibitor screening based on β-cyclodextrin-coated quantum dots. p-Nitrophenol, the hydrolysis product of the α-glucosidase reaction, could quench the fluorescence of β-cyclodextrin-coated quantum dots via an electron transfer process, leading to fluorescence turn-off, whereas the fluorescence of the system turned on in the presence of α-glucosidase inhibitors. Taking advantage of the excellent properties of quantum dots, this method provided a very simple, rapid and sensitive screening method for α-glucosidase inhibitors. Two α-glucosidase inhibitors, 2,4,6-tribromophenol and acarbose, were used to evaluate the feasibility of this screening model, and IC50 values of 24 μM and 0.55 mM were obtained respectively, which were lower than those previously reported. The method may have potential application in screening α-glucosidase inhibitors.

  1. 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

  2. Effects of Zn Content on Crystal Structure, Cytocompatibility, Antibacterial Activity, and Chemical Stability in Zn-Modified Calcium Silicate Coatings

    NASA Astrophysics Data System (ADS)

    Li, Kai; Yu, Jiangming; Xie, Youtao; Huang, Liping; Ye, Xiaojian; Zheng, Xuebin

    2013-08-01

    In our previous study, Zn-modified calcium silicate coatings possess not only excellent chemical stability but also well antibacterial activity. Still, effects of zinc content on these properties and cytocompatibility remain unclear. In this paper, two kinds of Zn-modified calcium silicate coatings (ZC0.3, ZC0.5) were fabricated on Ti-6Al-4V substrates via plasma spraying technology. X-ray diffraction results and transmission electron microscopy observations showed that the ZC0.5 coating was composed of pure hardystonite (Ca2ZnSi2O7) phase, while, besides Ca2ZnSi2O7 phase, the amorphous CaSiO3 phase was also detected in the ZC0.3 coating. Chemical stability in Tris-HCl buffer solution and antibacterial activity of the Zn-modified calcium silicate coatings increased with an increase in zinc content. In vitro cytocompatibility evaluation demonstrated that the proliferation and alkaline phosphatase activity and collagen type I (COLI) secretion of osteoblast-like MC3T3-E1 cells on Zn-modified coatings were significantly enhanced compared to the Zn-free coating and Ti-6Al-4V control, and no cytotoxicity appeared on Zn-modified coatings. The better antibacterial activity and the enhanced capability to promote MC3T3-E1 cells differentiation of Zn-modified coatings should be attributed to the slow and constant Zn2+ releasing from the coatings.

  3. Solution processable broadband transparent mixed metal oxide nanofilm optical coatings via substrate diffusion doping.

    PubMed

    Glynn, Colm; Aureau, Damien; Collins, Gillian; O'Hanlon, Sally; Etcheberry, Arnaud; O'Dwyer, Colm

    2015-12-21

    Devices composed of transparent materials, particularly those utilizing metal oxides, are of significant interest due to increased demand from industry for higher fidelity transparent thin film transistors, photovoltaics and a myriad of other optoelectronic devices and optics that require more cost-effective and simplified processing techniques for functional oxides and coatings. Here, we report a facile solution processed technique for the formation of a transparent thin film through an inter-diffusion process involving substrate dopant species at a range of low annealing temperatures compatible with processing conditions required by many state-of-the-art devices. The inter-diffusion process facilitates the movement of Si, Na and O species from the substrate into the as-deposited vanadium oxide thin film forming a composite fully transparent V0.0352O0.547Si0.4078Na0.01. Thin film X-ray diffraction and Raman scattering spectroscopy show the crystalline component of the structure to be α-NaVO3 within a glassy matrix. This optical coating exhibits high broadband transparency, exceeding 90-97% absolute transmission across the UV-to-NIR spectral range, while having low roughness and free of surface defects and pinholes. The production of transparent films for advanced optoelectronic devices, optical coatings, and low- or high-k oxides is important for planar or complex shaped optics or surfaces. It provides opportunities for doping metal oxides to ternary, quaternary or other mixed metal oxides on glass, encapsulants or other substrates that facilitate diffusional movement of dopant species.

  4. 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.

  5. Laser removal of TiN coatings from WC micro-tools and in-process monitoring

    NASA Astrophysics Data System (ADS)

    Marimuthu, S.; Kamara, A. M.; Whitehead, D.; Mativenga, P.; Li, L.

    2010-11-01

    Current environmental challenges require sustainable and extended use and re-use of materials. For example, the service life of engineering tooling can be extended by using thin film coatings such as titanium nitride (TiN). However, when errors arise in the coating process or when the tooling needs to be re-used it is necessary to remove the coating. Decoating is also useful when a large batch of cutting tools needs to be re-directed for a different application, which requires a new generation of coating. Existing technology uses chemical methods which are not environmentally friendly or ideal for selective removal. In this work, excimer laser striping of TiN from coated tungsten carbide (WC) micro-tools has been demonstrated as a viable alternative to chemical methods. Also, in order to raise the integrity of the decoating process and to make the process more accurate and reliable, two online monitoring systems were developed exploiting probe beam reflection (PBR) and laser plume emission spectroscopy (PES). The online monitoring system facilitated a simultaneous prediction of surface elements as coating layers are progressively removed and ensures better control over the laser irradiation process so as to avoid under or over stripping of the coating.

  6. Microwave-assisted combustion synthesis of nano iron oxide/iron-coated activated carbon, anthracite, cellulose fiber, and silica, with arsenic adsorption studies

    EPA Science Inventory

    Combustion synthesis of iron oxide/iron coated carbons such as activated carbon, anthracite, cellulose fiber and silica is described. The reactions were carried out in alumina crucibles using a Panasonic kitchen microwave with inverter technology, and the reaction process was com...

  7. Echicetin coated polystyrene beads: a novel tool to investigate GPIb-specific platelet activation and aggregation.

    PubMed

    Navdaev, Alexey; Subramanian, Hariharan; Petunin, Alexey; Clemetson, Kenneth J; Gambaryan, Stepan; Walter, Ulrich

    2014-01-01

    von Willebrand factor/ristocetin (vWF/R) induces GPIb-dependent platelet agglutination and activation of αIIbβ3 integrin, which also binds vWF. These conditions make it difficult to investigate GPIb-specific signaling pathways in washed platelets. Here, we investigated the specific mechanisms of GPIb signaling using echicetin-coated polystyrene beads, which specifically activate GPIb. We compared platelet activation induced by echicetin beads to vWF/R. Human platelets were stimulated with polystyrene beads coated with increasing amounts of echicetin and platelet activation by echicetin beads was then investigated to reveal GPIb specific signaling. Echicetin beads induced αIIbβ3-dependent aggregation of washed platelets, while under the same conditions vWF/R treatment led only to αIIbβ3-independent platelet agglutination. The average distance between the echicetin molecules on the polystyrene beads must be less than 7 nm for full platelet activation, while the total amount of echicetin used for activation is not critical. Echicetin beads induced strong phosphorylation of several proteins including p38, ERK and PKB. Synergistic signaling via P2Y12 and thromboxane receptor through secreted ADP and TxA2, respectively, were important for echicetin bead triggered platelet activation. Activation of PKG by the NO/sGC/cGMP pathway inhibited echicetin bead-induced platelet aggregation. Echicetin-coated beads are powerful and reliable tools to study signaling in human platelets activated solely via GPIb and GPIb-triggered pathways.

  8. Coating process and early stage adhesion evaluation of poly(2-hydroxy-ethyl-methacrylate) hydrogel coating of 316L steel surface for stent applications.

    PubMed

    Indolfi, Laura; Causa, Filippo; Netti, Paolo Antonio

    2009-07-01

    In this study, a spray-coating method has been set up with the aim to control the coating of poly(2-hydroxy-ethyl-methacrylate) (pHEMA), an hydrophilic polymeric hydrogel, onto the complex surface of a 316L steel stent for percutaneous coronary intervention (PCI). By varying process parameters, tuneable thicknesses, from 5 to 20 microm, have been obtained with uniform and homogeneous surface without crack or bridges. Surface characteristics of pHEMA coating onto metal surface have been investigated through FTIR-ATR, contact angle measurement, SEM, EDS and AFM. Moreover, results from Single-Lap-Joint and Pull-Off adhesion tests as well as calorimetric analysis of glass transition temperature suggested that pHEMA deposition is firmly adhered on metallic surface. The pHEMA coating evaluation of roughness, wettability together with its morphological and chemical stability after three cycles of expansion-crimping along with preliminary results after 6 months demonstrates the suitability of the coating for surgical implantation of stent.

  9. Influence of processing conditions on the thermal and mechanical properties of SU8 negative photoresist coatings

    NASA Astrophysics Data System (ADS)

    Feng, Ru; Farris, Richard J.

    2003-01-01

    The thermal and mechanical properties of a new negative photoresist, SU8, were characterized. The influence of curing conditions, such as baking temperature, baking time and UV dosage, on the thermal and mechanical properties of the resultant coatings was studied in detail. It was found that the glass-transition temperature (Tg) of the coatings was coincident with the baking temperature over the temperature range of 25 °C-220 °C for coatings being baked for just 20 min. However, the Tg reached a limiting value (about 240 °C) once the cross-linking reaction was complete, and would not increase further with the baking temperature. The peak temperature of the dimension versus temperature plots, where heat shrinkage occurred, was about a factor of 1.16 times higher than the baking temperature for the temperature range studied. Both the Tg and the shrinkage temperature were affected by the baking time. The thermal expansion coefficients (TEC), including the volumetric TEC (alphav), the in-plane TEC (alpha1) and the out-of-plane TEC (alpha2), were measured by a pressure-volume-temperature (PVT) apparatus and thermal-mechanical analyzer (TMA). Great residual stress could be generated during the process, and the change in residual stress with the environmental humidity was investigated using vibrational holographic interferometry.

  10. Deposition of TiSiN coatings by arc ion plating process

    NASA Astrophysics Data System (ADS)

    Guo, C. T.; Lee, D.; Chen, P. C.

    2008-03-01

    Titanium silicon nitride (TiSiN) thin films were deposited on tungsten cemented carbide tools by cathode arc ion plating (AIP) process using alloy TiSi targets. The effects of silicon addition and negative substrate bias on the development of the textures of films were studied systematically by varying the bias voltage from -20 to -200 V. The structural features of the films were investigated in detail using X-ray diffraction. The effect of the texture on such mechanical properties as hardness and adhesion of the films was also studied. A maximum hardness of 42 GPa was obtained at a DC substrate bias of -150 V. The characteristics of TiSiN thin films exhibited excellent adhesion of over 150 N. The cutting performance of end-mills and drillers was evaluated by milling and drilling of highly hardened material under high-speed cutting conditions. The results reveal that cutting tools with TiSiN coatings markedly outperformed those with TiN coatings, and the uncoated cutting tools. TiSiN coating increased the cutting lifetime to seven times that of the uncoated one.

  11. Rheological of chocolate-flavored, reduced-calories coating as a function of conching process.

    PubMed

    Medina-Torres, Luis; Sanchez-Olivares, Guadalupe; Nuñez-Ramirez, Diola Marina; Moreno, Leonardo; Calderas, Fausto

    2014-07-01

    Continuous flow and linear viscoelasticity rheology of chocolate coating is studied in this work using fat substitute gums (xanthan, GX). An alternative conching process, using a Rotor-Estator (RE) type impeller, is proposed. The objective is to obtain a chocolate coating material with improved flow properties. Characterization of the final material through particle size distribution (PSD), differential scanning calorimetry (DSC) and proximal analysis is reported. Particle size distribution of the final material showed less polydispersity and therefore, greater homogeneity; fusion points were also generated at around 20 °C assuming crystal type I (β'2) and II (α). Moreover, the final material exhibited crossover points (higher structure material), whereas the commercial brand chocolate used for comparison did not. The best conditions to produce the coating were maturing of 36 h and 35 °C, showing crossover points around 76 Pa and a 0.505 solids particle dispersion (average particle diameter of 0.364 μm), and a fusion point at 20.04 °C with a ΔHf of 1.40 (J/g). The results indicate that xanthan gum is a good substitute for cocoa butter and provides stability to the final product.

  12. Dynamic densification of metal matrix-coated fibre composites: modelling and processing

    SciTech Connect

    Peng, H.X.; Dunne, F.P.E. . E-mail: fionn.dunne@eng.ox.ac.uk; Grant, P.S.; Cantor, B.

    2005-02-01

    The consolidation processing of Ti-6Al-4V matrix-coated fibre (MCF) composite under vacuum hot pressing (VHP) has been investigated. A new test methodology has been developed for the determination of in situ matrix coating creep properties. In using the methodology, only a single, simple test is required, together with finite element modelling of the single fibre compression test. The creep coefficient and stress index have been determined for electron beam evaporated physical vapour deposited Ti-6Al-4V at 900 deg. C to be 1.23 x 10{sup -5} and 1.3, respectively. Consolidation experiments have been carried out on multi-ply MCF arrays under vacuum hot pressing. Finite element models have been developed for the dynamic consolidation of both square and hexagonal fibre packings. The creep constants for the Ti-6Al-4V, determined using the single fibre test, were assigned to the coating in the finite element models. Excellent agreement between predicted and experimental results was achieved, providing verification of the single fibre test methodology for the determination of creep constants.

  13. Livestock air treatment using PVA-coated powdered activated carbon biofilter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The efficacy of polyvinyl alcohol (PVA) biofilters was studied using bench-scale biofilters and air from aerobically-treated swine manure. The PVA-coated powdered activated carbon particles showed excellent properties as a biofiltration medium: water holding capacity of 1.39 g H2O/g-dry PVA; wet por...

  14. Livestock Air Treatment Using PVA-Coated Powdered Activated Carbon Biofilter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ideal biofilter media provide surface for attachment of microorganisms responsible for removing air-born contaminants while facilitating passage of air. This study evaluated the efficacy of polyvinyl alcohol (PVA)-coated powdered activated carbon particles as a biofiltration medium. This material e...

  15. Tuning the surface enhanced Raman scattering activity of gold nanocubes by silver coating

    NASA Astrophysics Data System (ADS)

    Ding, Shu-Jun; Zhu, Jian

    2015-12-01

    Colloidal gold nanocubes coated with a silver nanoshell have been synthesized via the seed mediated growth method. By changing the volume of gold seed and silver nitrate, both the edge length of gold nanocube and the thickness of silver shell could be fine-tuned. The surface-enhanced Raman scattering (SERS) activity of these core-shell structural Au-Ag bimetallic nanocubes has also been investigated by using the rhodamine 6G (R6G) as Raman active probe. It has been found the SERS activity of the silver-coated gold nanocubes greatly depends on their geometry factors. By decreasing the edge length of gold nanocubes or increasing the silver coating thickness, the SERS activity has been greatly enhanced. By comparing with other Raman bands of R6G, the enhancement of the Raman peak corresponding to the Csbnd Csbnd C ring in-plane vibration mode is more sensitive to the geometries of the nanostructure. These improved SERS properties of silver-coated gold nanocubes provide potential application for biologic and chemical sensing based on Raman spectroanalysis.

  16. Different virucidal activities of hyperbranched quaternary ammonium coatings on poliovirus and influenza virus.

    PubMed

    Tuladhar, Era; de Koning, Martijn C; Fundeanu, Irina; Beumer, Rijkelt; Duizer, Erwin

    2012-04-01

    Virucidal activity of immobilized quaternary ammonium compounds (IQACs) coated onto glass and plastic surfaces was tested against enveloped influenza A (H1N1) virus and nonenveloped poliovirus Sabin1. The IQACs tested were virucidal against the influenza virus within 2 min, but no virucidal effect against poliovirus was found in 6 h.

  17. Arsenic (III) adsorption on iron acetate coated activated alumina: thermodynamic, kinetics and equilibrium approach

    PubMed Central

    2013-01-01

    The adsorption potential of iron acetate coated activated alumina (IACAA) for removal of arsenic [As (III)] as arsenite by batch sorption technique is described. IACAA was characterized by XRD, FTIR, EDAX and SEM instruments. Percentage adsorption on IACAA was determined as a function of pH, contact time and adsorbent dose. The study revealed that the removal of As (III) was best achieved at pH =7.4. The initial As (III) concentration (0.45 mg/L) came down to less than 0.01 mg/L at contact time 90 min with adsorbent dose of 1 g/100 mL. The sorption was reasonably explained with Langmuir and Freundlich isotherms. The thermodynamic parameters such as ΔG 0 , ΔH 0 , ΔS 0 and E a were calculated in order to understand the nature of sorption process. The sorption process was found to be controlled by pseudo-second order and intraparticle diffusion models. PMID:24359995

  18. 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.

  19. 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.

  20. Self-assembled peptides for coating of active sulfur nanoparticles in lithium-sulfur battery

    NASA Astrophysics Data System (ADS)

    Jewel, Yead; Yoo, Kisoo; Liu, Jin; Dutta, Prashanta

    2016-03-01

    Development of lithium-sulfur (Li-S) battery is hindered by poor cyclability due to the loss of sulfur, although Li-S battery can provide high energy density. Coating of sulfur nanoparticles can help maintain active sulfur in the cathode of Li-S battery, and hence increase the cyclability. Among myriad of coating materials, synthetic peptides are very attractive because of their spontaneous self-assembly as well as electrical conductive characteristics. In this study, we explored the use of various synthetic peptides as a coating material for sulfur nanoparticles. Atomistic simulations were carried out to identify optimal peptide structure and density for coating sulfur nanoparticles. Three different peptide models, poly-proline, poly(leucine-lysine) and poly-histidine, are selected for this study based on their peptide-peptide and peptide-sulfur interactions. Simulation results show that both poly-proline and poly(leucine-lysine) can form self-assembled coating on sulfur nanoparticles (2-20 nm) in pyrrolidinone, a commonly used solvent for cathode slurry. We also studied the structural integrity of these synthetic peptides in organic [dioxolane (DOL) and dimethoxyethane (DME)] electrolyte used in Li-S battery. Both peptides show stable structures in organic electrolyte (DOL/DME) used in Li-S battery. Furthermore, the dissolution of sulfur molecules in organic electrolyte is investigated in the absence and presence of these peptide coatings. It was found that only poly(leucine-lysine)-based peptide can most effectively suppress the sulfur loss in electrolyte, suggesting its potential applications in Li-S battery as a coating material.

  1. Fabrication of silver-coated cobalt ferrite nanocomposite and the study of its antibacterial activity

    NASA Astrophysics Data System (ADS)

    Kooti, M.; Saiahi, S.; Motamedi, H.

    2013-05-01

    A new silver coated cobalt ferrite nanocomposite, Ag@CoFe2O4, was prepared by a two-step procedure. In the first step, cobalt ferrite nanoparticles were synthesized by a combustion method using glycine as a fuel. This ferrite was then coated with nanosilver via chemical reduction of Ag+ solution. The as-synthesized Ag@CoFe2O4 was characterized by X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The antibacterial activity of this composite was investigated against some Gram-positive and Gram-negative bacteria and compared with those of silver nanoparticles and some standard antibacterial drugs.

  2. Effect of Coatings and Processing on Failure Mechanisms of Polycarbonate Material. Phase 1

    DTIC Science & Technology

    1991-11-01

    brittle transition in the mechanical behavior of ballistically impacted polycarbonate materials with protective coatings . Polycarbonate embrittlement...pressures associated with the impact of polycarbonate material with and without protective coatings ; (2 ) Definition of polycarbonate substrate and coating ...is associated with the presence of protective coatings on the PC. It is desirable to investigate the mechanisms underlying this brittle failure and

  3. Diamond-coated fiber Bragg grating through the hot filament chemical vapor process for chemical durability improvement.

    PubMed

    Alberto, Nélia; José Kalinowski, Hypolito; Neto, Victor; Nogueira, Rogério

    2017-02-20

    In recent years, the coating of fiber Bragg gratings (FBGs) with a specific material has opened up the possibility to broaden the limits of applicability of this technology. Diamond has a set of properties that makes it an attractive candidate to protect the optical fiber against chemically harsh environments, whose sensing is also a great challenge. One of the most used techniques to obtain these coatings is through the hot filament chemical vapor deposition (HFCVD); in this process, the temperature reaches, typically, around 850°C-900°C. In this work, the regeneration of a seed FBG during its coating with a nanocrystalline diamond thin film through the HFCVD process is presented. Simultaneously, the thermal monitoring of the process was also performed using the same grating. The resistance test in a corrosive medium reveals an improvement on the durability of the sensing properties of the diamond-coated FBG compared with an uncoated FBG, foreseeing a vast range of applications.

  4. Development of the Process Index for NiCrAlY Coatings with the Mettech Axial III™ System

    NASA Astrophysics Data System (ADS)

    Gao, Feng; Yang, Qi; Huang, Xiao; Liu, Rong

    2013-03-01

    NiCrAlY coatings were deposited using the Mettech Axial III™ plasma spray system. The microstructural features of the coatings, such as the porosity, crack, un-melted particle, and oxide content, were analyzed to investigate the effects of the spray process parameters on these features. Two Taguchi arrays were used to examine the effects of the spray process parameters such as powder size, ratio of (H2 + N2) gas flow over total gas flow, current, spray-gun nozzle size, and spray distance, on the microstructural features of the coatings. The results from statistical analysis are used to create regression equations to predict the microstructural features of the coatings. In the regression equations, a process index (PI) is used as a complex variable incorporating a number of process parameters. The results from an additional set of experiments are used to verify the validity of the regression equations. It has been demonstrated that the equations correlate well with the results from the subsequent set of experiments. It is concluded from this study that the PI can be used to categorize coating qualities with respect to the extent of crack, porosity, unmelted particle, and oxide content in the coating. These equations can also serve as an initial step in developing process parameters by means of the Mettech Axial III™ System.

  5. Process for the formation of wear- and scuff-resistant carbon coatings

    DOEpatents

    Malaczynski, Gerard W.; Qiu, Xiaohong; Mantese, Joseph V.; Elmoursi, Alaa A.; Hamdi, Aboud H.; Wood, Blake P.; Walter, Kevin C.; Nastasi, Michael A.

    1995-01-01

    A process for forming an adherent diamond-like carbon coating on a workpiece of suitable material such as an aluminum alloy is disclosed. The workpiece is successively immersed in different plasma atmospheres and subjected to short duration, high voltage, negative electrical potential pulses or constant negative electrical potentials or the like so as to clean the surface of oxygen atoms, implant carbon atoms into the surface of the alloy to form carbide compounds while codepositing a carbonaceous layer on the surface, bombard and remove the carbonaceous layer, and to thereafter deposit a generally amorphous hydrogen-containing carbon layer on the surface of the article.

  6. Heating process and damage threshold analysis of Au film coated on Cu substrate for femtosecond laser

    NASA Astrophysics Data System (ADS)

    Wang, Tingfeng; Guo, Jin; Shao, Junfeng; Sun, Tao; Chen, Anmin; Liu, Hang; Ding, Dajun

    2012-07-01

    The heating processes of a two-layer film assembly of Au padded with Cu irradiated by femtosecond laser pulse are studied using a two-temperature model. It is found that the chosen substantially influence the energy transport, and consequently the temperature variation, and thermal equilibrium time. At the same laser fluence, the different thickness of gold film leads to a change of gold surface temperature. By choosing the thickness of the gold layer in the two-layer film assemblies, the damage threshold of the gold film can be maximized. The results can be used to optimize the damage threshold of gold coating optical components.

  7. Gliding arc surface modification of carrot nanofibre coating - perspective for composite processing

    NASA Astrophysics Data System (ADS)

    Kusano, Y.; Berglund, L.; Aitomäki, Y.; Oksman, K.; Madsen, B.

    2016-07-01

    Surfaces of carrot nanofibre coatings were modified by a gliding arc in atmospheric pressure air. The treatment strengthened wetting of deionized water and glycerol, increased an oxygen content, C-O and C=O, and moderately roughened the surfaces. In the perspective of composite materials, these changes to the nanofibres can potentially improve their processability when they are to be impregnated with a polymeric matrix. However, longer exposure to the gliding arc reduced oxidation and roughness of the surface, and thus there exists an optimum condition to achieve good wetting to solvents.

  8. Development of processing procedures for advanced silicon solar cells. [antireflection coatings and short circuit currents

    NASA Technical Reports Server (NTRS)

    Scott-Monck, J. A.; Stella, P. M.; Avery, J. E.

    1975-01-01

    Ten ohm-cm silicon solar cells, 0.2 mm thick, were produced with short circuit current efficiencies up to thirteen percent and using a combination of recent technical advances. The cells were fabricated in conventional and wraparound contact configurations. Improvement in cell collection efficiency from both the short and long wavelengths region of the solar spectrum was obtained by coupling a shallow junction and an optically transparent antireflection coating with back surface field technology. Both boron diffusion and aluminum alloying techniques were evaluated for forming back surface field cells. The latter method is less complicated and is compatible with wraparound cell processing.

  9. A novel processing of carbon nanotubes grown on molecular sieve coated porous ceramics

    NASA Astrophysics Data System (ADS)

    Mazumder, Sangram; Sarkar, Naboneeta; Park, Jung Gyu; Zhao, Wei; Kim, Sukyoung; Kim, Ik Jin

    2015-08-01

    The present study focuses on the growth of carbon nanotubes (CNTs) on Fe-containing zeolites coated porous ceramics by implementing three different and independent techniques, successively. Direct foaming-derived porous ceramics were subjected to hydrothermal reaction for on-site growth of NaA zeolites within it. The porous ceramics-zeolite composite was subjected to ion-exchange reaction to obtain the catalyst for CNT synthesis. Multi-walled CNTs (MWCNTs) were grown by catalytic chemical vapour deposition (CCVD) process using acetylene as carbon source. Microstructural, thermogravimetric and spectroscopic analyses showed distinctive differences in terms of hollow structural feature, yield and crystallinity of the MWCNTs with different reaction temperatures.

  10. Novel Active Surface Prepared by Embedded Functionalized Clays in an Acrylate Coating.

    PubMed

    Xia, Yining; Ghasemlou, Mehran; Rubino, Maria; Auras, Rafael; Baghdachi, Jamil

    2015-11-11

    The research on a self-decontaminating surface has received significant attention because of the growth of pathogenic microorganisms on surfaces. In this study, a novel and simple technique for producing an active surface with antimicrobial functionality is demonstrated. A tethering platform was developed by grafting the biocide ampicillin (Amp) to a nanoclay and dispersing the nanoclay in a UV-curable acrylate coating applied on polypropylene films as the substrate. A coupling agent, [3-(glycidyloxy)propyl]trimethoxysilane, was used as a linker between the nanoclay and Amp. The Amp-functionalized clay was further modified with an organic surfactant to improve the compatibility with the coating. Several characterization assays, such as Fourier infrared transform analysis, thermogravimetric analysis, and X-ray diffraction, were conducted to confirm the presence of Amp in the nanoclay. Transmission electron microscopy images revealed that the clay particles were well dispersed in the coating and had a partial exfoliated morphology. The active coating surface was effective in inhibiting the growth of Gram-positive Listeria monocytogenes and Gram-negative Salmonella Typhimurium via contact. These findings suggest the potential for the development of active surfaces with the implementation of nanotechnology to achieve diverse functionalities.

  11. Active wear and failure mechanisms of TiN-coated high speed steel and TiN-coated cemented carbide tools when machining powder metallurgically made stainless steels

    SciTech Connect

    Jiang, L.; Haenninen, H.; Paro, J.; Kauppinen, V.

    1996-09-01

    In this study, active wear and failure mechanisms of both TiN-coated high speed steel and TiN-coated cemented carbide tools when machining stainless steels made by powder metallurgy in low and high cutting speed ranges, respectively, have been investigated. Abrasive wear mechanisms, fatigue-induced failure, and adhesive and diffusion wear mechanisms mainly affected the tool life of TiN-coated high speed steel tools at cutting speeds below 35 m/min, between 35 and 45 m/min, and over 45 m/min, respectively. Additionally, fatigue-induced failure was active at cutting speeds over 45 m/min in the low cutting speed range when machining powder metallurgically made duplex stainless steel 2205 and austenitic stainless steel 316L. In the high cutting speed range, from 100 to 250 m/min, fatigue-induced failure together with diffusion wear mechanism, affected the tool life of TiN-coated cemented carbide tools when machining both 316L and 2205 stainless steels. It was noticed that the tool life of TiN-coated high speed steel tools used in the low cutting speed range when machining 2205 steel was longer than that when machining 316L steel, whereas the tool life of TiN-coated cemented carbide tools used in the high cutting speed range when machining 316L steel was longer than that when machining 2205 steel.

  12. Active wear and failure mechanisms of TiN-Coated high speed steel and tin-coated cemented carbide tools when machining powder metallurgically made stainless steels

    NASA Astrophysics Data System (ADS)

    Jiang, Laizhu; Hänninen, Hannu; Paro, Jukka; Kauppinen, Veijo

    1996-09-01

    In this study, active wear and failure mechanisms of both TiN-coated high speed steel and TiN-coated cemented carbide tools when machining stainless steels made by powder metallurgy in low and high cutting speed ranges, respectively, have been investigated. Abrasive wear mechanisms, fatigue-induced failure, and adhesive and diffusion wear mechanisms mainly affected the tool life of TiN-coated high speed steel tools at cutting speeds below 35 m/min, between 35 and 45 m/min, and over 45 m/min, respectively. Additionally, fatigue-induced failure was active at cutting speeds over 45 m/min in the low cutting speed range when machining powder metallurgically made duplex stainless steel 2205 and austenitic stainless steel 316L. In the high cutting speed range, from 100 to 250 m/min, fatigue-induced failure together with diffusion wear mechanism, affected the tool life of TiN-coated cemented carbide tools when machining both 316L and 2205 stainless steels. It was noticed that the tool life of TiN-coated high speed steel tools used in the low cutting speed range when machining 2205 steel was longer than that when machining 316L steel, whereas the tool life of TiN-coated cemented carbide tools used in the high cutting speed range when machining 316L steel was longer than that when machining 2205 steel.

  13. Preparation of metal oxide thin films using coating photolysis process with ArF excimer laser

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Tetsuo; Watanabe, Akio; Imai, Yoji; Niino, Hiroyuki; Yabe, Akira; Yamaguchi, Iwao; Manabe, Takaaki; Kumagai, Toshiya; Mizuta, Susumu

    2000-11-01

    The preparation of metal oxide thin films have been developed using the metalorganic (MO) compounds coating photolysis process with ArF excimer laser irradiation at room temperature. The effect of the starting materials and irradiation method on the product films was investigated by FT-IR, UV, XRD and SEM. It was found that metal acetylacetonates or metal 2-ethylhexanoate was effective as the starting materials. When using metal acetylacetonates as the starting materials, crystallized TiO2, In2O3 and ZrO2 were obtained with ArF laser irradiation at 50 mJ/cm2 at a repetition rate of 5 Hz for 5 min. When using An-acac, Fe, Sn, or In 2-ethylhexanoate as the starting material, a two-step process consisting of both preliminary weak (10mJ/cm2) and sufficiently strong irradiation (50mJ/cm2) was found to be effective for obtaining crystallized ZnO, Fe2O3, SnO2 and In2O3 films. In addition, crystallized complex oxide thin films such as ITO, PbTo3 and PbZrO3 were successfully obtained from the metal acetylacetonates or metal 2-ethylhexanoate using MO coating photolysis process. Patterned metal oxide thin films were also obtained by the ArF laser irradiation through the photomask, followed by leaching with solvents. The crystallization mechanism was discussed from the point of view of the photochemical reaction and photothermal reaction.

  14. Effect of Solid Shield on Coating Properties in Atmospheric Plasma Spray Process

    NASA Astrophysics Data System (ADS)

    Liu, Ting; Zheng, Lili; Zhang, Hui

    2016-12-01

    This paper investigates the impact of shrouded shield structure on plasma spray processes and the selection of optimal shield structure. Response of plasma flame characteristics to solid shield structures is studied first, and experimental investigations are then performed for both atmospheric (APS) and shrouded (SPS) plasma spray processes. It is found that the usage of conical shield (divergence angle 5.5°) with 90 mm in length is effective to form a low-oxygen (<2%) and high-temperature (>3000 K) region in the plasma flame and this region can cover the majority area for particles passing by. The average particle temperature is higher in SPS than in APS with the given conditions, and such behavior is intensified as solid shield length increases. Using the SPS process, more disk-shaped splats are obtained, and the oxygen concentration in coating is significantly reduced. The degree of the oxidation in the coatings is further reduced as the length of the solid shield increases from 50 to 90 mm. Applying solid shield will lead to high flame temperature and low oxidation; however, the substrate overheating and velocity reduction may occur. For the cases studied, the optimal shield length is around 90 mm.

  15. Enhanced activity of immobilized pepsin nanoparticles coated on solid substrates compared to free pepsin.

    PubMed

    Meridor, David; Gedanken, Aharon

    2014-12-01

    In the present work nanoparticles (NPs) of pepsin were generated in an aqueous solution using high-intensity ultrasound, and were subsequently immobilized on low-density polyethylene (PE) films, or on polycarbonate (PC) plates, or on microscope glass slides. The pepsin NPs coated on the solid surfaces have been characterized by HRSEM, TEM, FTIR, XPS and DLS. The amount of enzyme introduced on the substrates, the leaching properties, and the catalytic activity of the immobilized enzyme on the three surfaces are compared. Catalytic activities of pepsin deposited onto the three solid surfaces as well as free pepsin, without sonication, and free pepsin NPs were compared at various pH levels and temperatures using a hemoglobin assay. Compared to native pepsin, pepsin coated onto PE showed the best catalytic activity in all the examined parameters. Pepsin immobilized on glass exhibited better activity than the native enzyme, especially at high temperatures. Enzyme activity of pepsin immobilized on PC was no better than native enzyme activity at all temperatures at pH 2, and only over a narrow pH range at 37°C was the activity improved over the native enzyme. A remarkable observation is that immobilized pepsin on all the surfaces was still active to some extent even at pH 7, while free pepsin was completely inactive. The kinetic parameters, Km and Vmax were also calculated and compared for all the samples. Relative to the free enzyme, pepsin coated PE showed the greatest improvement in kinetic parameters (Km=15g/L, Vmax=719U/mg versus Km=12.6g/L and Vmax=787U/mg, respectively), whereas pepsin coated on PC exhibited the most unfavorable kinetic parameters (Km=18g/L, Vmax=685U/mg). The values for the anchored enzyme-glass were Km=19g/L, Vmax=763U/mg.

  16. Volatile species in halide-activated-diffusion coating packs

    NASA Technical Reports Server (NTRS)

    Bianco, Robert; Rapp, Robert A.; Jacobson, Nathan S.

    1992-01-01

    An atmospheric pressure sampling mass spectrometer was used to identify the vapor species generated in a halide-activated cementation pack. Pack powder mixtures containing a Cr-Al binary masteralloy powder, an NH4Cl activator salt, and either ZrO2 or Y2O3 (or neither) were analyzed at 1000 C. Both the equilibrium calculations for the pack and mass spectrometer results indicated that volatile AlCl(x) and CrCl(y) species were generated by the pack powder mixture; in packs containing the reactive element oxide, volatile ZrCl(z) and YCl(w) species were formed by the conversion of their oxide sources.

  17. In vitro antiplasmodial activity of PDDS-coated metal oxide nanoparticles against Plasmodium falciparum

    NASA Astrophysics Data System (ADS)

    Jacob Inbaneson, Samuel; Ravikumar, Sundaram

    2013-06-01

    Malaria is the most important parasitic disease, leading to annual death of about one million people and the Plasmodium falciparum develops resistant to well-established antimalarial drugs. The newest antiplasmodial drug from metal oxide nanoparticles helps in addressing this problem. Commercial nanoparticles such as Fe3O4, MgO, ZrO2, Al2O3 and CeO2 coated with PDDS and all the coated and non-coated nanoparticles were screened for antiplasmodial activity against P. falciparum. The Al2O3 nanoparticles (71.42 ± 0.49 μg ml-1) showed minimum level of IC50 value and followed by MgO (72.33 ± 0.37 μg ml-1) and Fe3O4 nanoparticles (77.23 ± 0.42 μg ml-1). The PDDS-Fe3O4 showed minimum level of IC50 value (48.66 ± 0.45 μg ml-1), followed by PDDS-MgO (60.28 ± 0.42 μg ml-1) and PDDS-CeO2 (67.06 ± 0.61 μg ml-1). The PDDS-coated metal oxide nanoparticles showed superior antiplasmodial activity than the non-PDDS-coated metal oxide nanoparticles. Statistical analysis reveals that, significant in vitro antiplasmodial activity ( P < 0.05) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes showed no morphological changes in erythrocytes by the nanoparticles after 48 h of incubation. It is concluded from the present study that, the PDDS-Fe3O4 showed good antiplasmodial activity and it might be used for the development of antiplasmodial drugs.

  18. Anti-listerial activity of a polymeric film coated with hybrid coatings doped with Enterocin 416K1 for use as bioactive food packaging.

    PubMed

    Iseppi, Ramona; Pilati, Francesco; Marini, Michele; Toselli, Maurizio; de Niederhäusern, Simona; Guerrieri, Elisa; Messi, Patrizia; Sabia, Carla; Manicardi, Giuliano; Anacarso, Immacolata; Bondi, Moreno

    2008-04-30

    In this study, Enterocin 416K1, a bacteriocin produced by Enterococcus casseliflavus IM 416K1, was entrapped in an organic-inorganic hybrid coating applied to a LDPE (low-density polyethylene) film for its potential use in the active food packaging field. The antibacterial activity of the coated film was evaluated against Listeria monocytogenes NCTC 10888 by qualitative modified agar diffusion assay, quantitative determination in listeria saline solution suspension and direct contact with artificially contaminated food samples (frankfurters and fresh cheeses) stored at room and refrigeration temperatures. All investigations demonstrated that enterocin-activated coatings have a good anti-listeria activity. Qualitative tests showed a clear zone of inhibition in the indicator lawn in contact with and around the coated film. During the quantitative antibacterial evaluation the L. monocytogenes viable counts decreased to 1.5 log units compared to the control. The inhibitory capability was confirmed also in food-contact assays. In all food samples packed with coated films we observed a significant decrease in L. monocytogenes viable counts in the first 24 h compared to the control. This difference was generally maintained up to the seventh day and then decreased, with the exception of the cheese samples stored at refrigeration temperature.

  19. Activated platelets form protected zones of adhesion on fibrinogen and fibronectin-coated surfaces

    PubMed Central

    1993-01-01

    Leukocytes form zones of close apposition when they adhere to ligand- coated surfaces. Because plasma proteins are excluded from these contact zones, we have termed them protected zones of adhesion. To determine whether platelets form similar protected zones of adhesion, gel-filtered platelets stimulated with thrombin or ADP were allowed to adhere to fibrinogen- or fibronectin-coated surfaces. The protein- coated surfaces with platelets attached were stained with either fluorochrome-conjugated goat anti-human fibrinogen or anti-human fibronectin antibodies, or with rhodamine-conjugated polyethylene glycol polymers. Fluorescence microscopy revealed that F(ab')2 anti- fibrinogen (100 kD) did not penetrate into the contact zones between stimulated platelets and the underlying fibrinogen-coated surface, while Fab antifibrinogen (50 kD) and 10 kD polyethylene glycol readily penetrated and stained the substrate beneath the platelets. Thrombin- or ADP-stimulated platelets also formed protected zones of adhesion on fibronectin-coated surfaces. F(ab')2 anti-fibronectin and 10 kD polyethylene glycol were excluded from these adhesion zones, indicating that they are much less permeable than those formed by platelets on fibrinogen-coated surfaces. The permeability properties of protected zones of adhesion formed by stimulated platelets on surfaces coated with both fibrinogen and fibronectin were similar to the zones of adhesion formed on fibronectin alone. mAb 7E3, directed against the alpha IIb beta 3 integrin blocked the formation of protected adhesion zones between thrombin-stimulated platelets and fibrinogen or fibronectin coated surfaces. mAb C13 is directed against the alpha 5 beta 1 integrin on platelets. Stimulated platelets treated with this mAb formed protected zones of adhesion on surfaces coated with fibronectin. These protected zones were impermeable to F(ab')2 antifibronectin but were permeable to 10 kD polyethylene glycol. These results show that activated

  20. Superomniphobic and easily repairable coatings on copper substrates based on simple immersion or spray processes.

    PubMed

    Rangel, Thomaz C; Michels, Alexandre F; Horowitz, Flávio; Weibel, Daniel E

    2015-03-24

    Textures that resemble typical fern or bracken plant species (dendrite structures) were fabricated for liquid repellency by dipping copper substrates in a single-step process in solutions containing AgNO3 or by a simple spray liquid application. Superhydrophobic surfaces were produced using a solution containing AgNO3 and trimethoxypropylsilane (TMPSi), and superomniphobic surfaces were produced by a two-step procedure, immersing the copper substrate in a AgNO3 solution and, after that, in a solution containing 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES). The simple functionalization processes can also be used when the superomniphobic surfaces were destroyed by mechanical stress. By immersion of the wrecked surfaces in the above solutions or by the spray method and soft heating, the copper substrates could be easily repaired, regenerating the surfaces' superrepellency to liquids. The micro- and nanoroughness structures generated on copper surfaces by the deposition of silver dendrites functionalized with TMPSi presented apparent contact angles greater than 150° with a contact angle hysteresis lower than 10° when water was used as the test liquid. To avoid total wettability with very low surface tension liquids, such as rapeseed oil and hexadecane, a thin perfluorinated coating of poly(tetrafluoroethylene) (PTFE), produced by physical vapor deposition, was used. A more efficient perfluorinated coating was obtained when PFDTES was used. The superomniphobic surfaces produced apparent contact angles above 150° with all of the tested liquids, including hexadecane, although the contact angle hysteresis with this liquid was above 10°. The coupling of dendritic structures with TMPSi/PTFE or directly by PFDTES coatings was responsible for the superrepellency of the as-prepared surfaces. These simple, fast, and reliable procedures allow the large area, and cost-effective scale fabrication of superrepellent surfaces on copper substrates for various industrial

  1. A capacitive technique for real-time monitoring polymer coating thickness on carbon filaments during prepregging process

    NASA Technical Reports Server (NTRS)

    Eftekhari, Abe; Chapman, John J.

    1989-01-01

    A technique for gauging the coating thickness during prepreg processing of carbon fibers was developed. It is based on the concept of measuring the capacitance of a cylindrical condenser through which a bundle of prepregged fibers is passed axially. Empirical results indicate the capacitance of this condenser element is linearly related to the polymer coating thickness on the fibers in the bundle. The capacitive transducer was successfully used to measure the polymer thickness on several test fiber bundles under static conditions.

  2. [Emission characteristics and safety evaluation of volatile organic compounds in manufacturing processes of automotive coatings].

    PubMed

    Zeng, Pei-Yuan; Li, Jian-Jun; Liao, Dong-Qi; Tu, Xiang; Xu, Mei-Ying; Sun, Guo-Ping

    2013-12-01

    Emission characteristics of volatile organic compounds (VOCs) were investigated in an automotive coating manufacturing enterprise. Air samples were taken from eight different manufacturing areas in three workshops, and the species of VOCs and their concentrations were measured by gas chromatography-mass spectrometry (GC-MS). Safety evaluation was also conducted by comparing the concentration of VOCs with the permissible concentration-short term exposure limit (PC-STEL) regulated by the Ministry of Health. The results showed that fifteen VOCs were detected in the indoor air of the automotive coatings workshop, including benzene, toluene, ethylbenzene, xylene, ethyl acetate, butyl acetate, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, trimethylbenzene and ethylene glycol monobutyl ether, Their concentrations widely ranged from 0.51 to 593.14 mg x m(-3). The concentrations of TVOCs were significantly different among different manufacturing processes. Even in the same manufacturing process, the concentrations of each component measured at different times were also greatly different. The predominant VOCs of indoor air in the workshop were identified to be ethylbenzene and butyl acetate. The concentrations of most VOCs exceeded the occupational exposure limits, so the corresponding control measures should be taken to protect the health of the workers.

  3. Ultrathin hexagonal MgO nanoflakes coated medical textiles and their enhanced antibacterial activity

    NASA Astrophysics Data System (ADS)

    Veeran Ponnuvelu, Dinesh; Selvaraj, Aravind; Prema Suriyaraj, Shanmugam; Selvakumar, Rajendran; Pulithadathail, Biji

    2016-10-01

    A facile hydrothermal method for development of ultrathin MgO nanoplates from different precursors and their enhanced antibacterial activity after coating onto medical textiles is reported. Ultrathin MgO nanoplates having hexagonal structure were characterized using UV-visible spectroscopy, atomic force microscopy, field emission scanning electron microscopy, x-ray diffraction and high resolution transmission electron microscopy. The formation of MgO nanoplates was found to exhibit profound anionic effect leading to ultrathin, planar structures with exposed MgO [111] facets, which may be responsible for enhanced antimicrobial activity. Medical fabrics (bleached 100% cotton) were coated with MgO nanoplates using pad-dry-cure method. The antibacterial activity of these fabrics was tested against Bacillus subtilis and Escherichia coli. The MgO nanoplates coated onto the fabric were found to have good adherence properties owing to their two-dimensional structure and were durable even after repeated washings without substantial reduction in the antimicrobial activity. The enhanced antibacterial activity may be attributed to the presence of oxygen vacancies, surface oxygen anions and hydroxyl groups on the surface of MgO nanoplates. This cost-effective functional finish (anti-microbial) to cotton fabric using MgO nanoplates may be suitable for many prospective medical applications and can serve as an alternative to the costlier silver based antimicrobial textiles.

  4. Polymeric active coatings with functionality in vascular applications.

    PubMed

    Aguilar, María Rosa; Rodríguez, Gema; Fernández, Mar; Gallardo, Alberto; San Román, Julio

    2002-12-01

    Copolymers containing functional groups with activity as antiaggregating agents for platelets, based on random chains of metacryloyloxyethyl [2-(acetyloxy)-4-(trifluoromethyl)]benzoate, TH, and 2-acrylamido-2-metylpropanesulfonic acid, AMPS, with AMPS molar fractions ranging from 0.1 to 0.4, have been prepared. The spectroscopical characterization and the in vitro swelling behavior have been studied, as well as the surface free energy, showing the copolymers an appropriate surface properties from a haemocompatible point of view. Preliminary in vitro tests using human blood have shown a promising antiaggregating behavior.

  5. Energetics of active transport processes.

    PubMed

    Essig, A; Caplan, S R

    1968-12-01

    Discussions of active transport usually assume stoichiometry between the rate of transport J(+) and the metabolic rate J(r). However, the observation of a linear relationship between J(+) and J(r) does not imply a stoichiometric relationship, i.e., complete coupling. Since coupling may possibly be incomplete, we examine systems of an arbitrary degree of coupling q, regarding stoichiometry as a limiting case. We consider a sodium pump, with J(+) and J(r) linear functions of the electrochemical potential difference, -X(+), and the chemical affinity of the metabolic driving reaction, A. The affinity is well defined even for various complex reaction pathways. Incorporation of a series barrier and a parallel leak does not affect the linearity of the composite observable system. The affinity of some region of the metabolic chain may be maintained constant, either by large pools of reactants or by regulation. If so, this affinity can be evaluated by two independent methods. Sodium transport is conveniently characterized by the open-circuit potential (Deltapsi)(I=0) and the natural limits, level flow (J(+))(X+=0), and static head X(0) (+) = (X(+))(J+=0). With high degrees of coupling -X(0) (+)/F approaches the electromotive force E(Na) (Ussing); -X(0) (+)/F cannot be identified with ((RT/F) ln f)(X+=0), where f is the flux ratio. The efficiency eta = -J(+)X(+)/J(r)A is of significance only when appreciable energy is being converted from one form to another. When either J(+) or -X(+) is small eta is low; the significant parameters are then the efficacies epsilon(J+) = J(+)/J(r)A and epsilon(X+) = -X(+)/J(r)A, respectively maximal at level flow and static head. Leak increases both J(+) and epsilon(J+) for isotonic saline reabsorption, but diminishes -X(0) (+) and epsilon(Xfemale symbol). Electrical resistance reflects both passive parameters and metabolism. Various fundamental relations are preserved despite coupling of passive ion and water flows.

  6. Novel solvent-free direct coating process for battery electrodes and their electrochemical performance

    NASA Astrophysics Data System (ADS)

    Park, Dong-Won; Cañas, Natalia A.; Wagner, Norbert; Friedrich, K. Andreas

    2016-02-01

    We report a novel solvent-free direct coating process for fabricating a well-structured electrode. The manufacturing process was rapid and facile, involving only dry-spraying of the solvent-free electrode component mixture and a subsequent isothermal hot-pressing. The electrochemical and physicochemical properties of the dry-sprayed electrode with hot-pressing were evaluated in order to understand the correlation between a preparation parameter, morphological characteristic of the electrode, and cell performance. The hot-pressing time had an effect on the binder distribution, which in turn resulted in different electrode morphologies and performance. The dry-sprayed LTO electrode prepared at a hot-pressing time of 60 min had excellent electrical conductivity and Li+ storage capacity, owing to its electron transport structure, which was more suitable than the prepared electrodes at other hot-pressing conditions.

  7. High-peak-irradiance microwave-powered UV lamps for processing of coatings, inks, and adhesives

    NASA Astrophysics Data System (ADS)

    Stowe, Richard W.

    1993-01-01

    The number and variety of applications for UV curable inks, coatings, and adhesives continue to expand at a rapid pace, and pose new design challenges to increase cure efficiency, speed, and the physical properties of the cured polymer film. The latest developments in microwave powered lamps for industrial processing are presented. Among these are: (1) the selection and control of the lamp emission spectra to match the optical properties of the film and its photoinitiator, (2) sustained high power lamp operation at 6 kilowatts, and (3) the use of absorptive dichroic reflectors to mange the relative components of UV and infrared energy in the highly focused radiation delivered to surfaces being processed. The design considerations of high powered UV lamps and dichroic reflectors for them are presented.

  8. Application of edible coating with starch and carvacrol in minimally processed pumpkin.

    PubMed

    Santos, Adriele R; da Silva, Alex F; Amaral, Viviane C S; Ribeiro, Alessandra B; de Abreu Filho, Benicio A; Mikcha, Jane M G

    2016-04-01

    The present study evaluated the effect of an edible coating of cassava starch and carvacrol in minimally processed pumpkin (MPP). The minimal inhibitory concentration (MIC) of carvacrol against Escherichia coli, Salmonella enterica serotype Typhimurium, Aeromonas hydrophila, and Staphylococcus aureus was determined. The edible coating that contained carvacrol at the MIC and 2 × MIC was applied to MPP, and effects were evaluated with regard to the survival of experimentally inoculated bacteria and autochthonous microflora in MPP. Total titratable acidity, pH, weight loss, and soluble solids over 7 days of storage under refrigeration was also analyzed. MIC of carvacrol was 312 μg/ml. Carvacrol at the MIC reduced the counts of E. coli and S. Typhimurium by approximately 5 log CFU/g. A. hydrophila was reduced by approximately 8 log CFU/g, and S. aureus was reduced by approximately 2 log CFU/g on the seventh day of storage. Carvacrol at the 2 × MIC completely inhibited all isolates on the first day of Storage. coliforms at 35 °C and 45 °C were not detected (< 3 MPN/g) with either treatment on all days of shelf life. The treatment groups exhibited a reduction of approximately 2 log CFU/g in psychrotrophic counts compared with controls on the last day of storage. Yeast and mold were not detected with either treatment over the same period. The addition of carvacrol did not affect total titratable acidity, pH, or soluble solids and improved weight loss. The edible coating of cassava starch with carvacrol may be an interesting approach to improve the safety and microbiological quality of MPP.

  9. Antimicrobial activity of allyl isothiocyanate used to coat biodegradable composite films as affected by storage and handling conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the effects of storage and handling conditions on the antimicrobial activity of biodegradable composite films (polylactic acid and sugar beet pulp) coated with allyl isothiocyanate (AIT). Polylactic acid (PLA) and chitosan were incorporated with AIT and coated on one side of the film. T...

  10. The behavior of active bactericidal and antifungal coating under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Xiao, Gang; Zhang, Xiaodong; Zhao, Yan; Su, Haijia; Tan, Tianwei

    2014-02-01

    In the present paper, the novel active bactericidal and antifungal coatings (ABAC) have been prepared through the immobilization of Fe-doped TiO2 (anatase) with chitosan. The characterization of ABAC using optical microscope imaging, SEM, AFM and FTIR shows that the Fe doped TiO2 is embedded into the chitosan coating with favorable dispersion through the hydrogen bonds interaction between chitosan molecules and TiO2. The contact angle measurement demonstrated the hydrophilicity of ABAC (θ = 34.5 ± 4.1°). The bactericidal activity of ABAC has been evaluated by inactivating three different test strains: Escherichia coli, Candida albicans and Aspergillus niger which illustrates the apparently higher bactericidal ability than chitosan, Fe-TiO2 and chitosan/TiO2 (pure) under visible light irradiation and its bactericidal activity is lasting for at least 24 h. ABAC showed rapid and efficient antibacterial ability for the three tested strains and its antibacterial ratio in 2 h for E. coli, C. albicans and A. niger was 99.9%, 97.0% and 95.0%, respectively. The prepared chitosan/TiO2 composite emulsion shows favorable storage stability and can be stored up to 1 year without losing its bactericidal activity. ABAC is a low-cost and eco-friendly antibacterial coating products and promising for domestic, medical and industrial applications.

  11. Size and Aging Effects on Antimicrobial Efficiency of Silver Nanoparticles Coated on Polyamide Fabrics Activated by Atmospheric DBD Plasma.

    PubMed

    Zille, Andrea; Fernandes, Margarida M; Francesko, Antonio; Tzanov, Tzanko; Fernandes, Marta; Oliveira, Fernando R; Almeida, Luís; Amorim, Teresa; Carneiro, Noémia; Esteves, Maria F; Souto, António P

    2015-07-01

    This work studies the surface characteristics, antimicrobial activity, and aging effect of plasma-pretreated polyamide 6,6 (PA66) fabrics coated with silver nanoparticles (AgNPs), aiming to identify the optimum size of nanosilver exhibiting antibacterial properties suitable for the manufacture of hospital textiles. The release of bactericidal Ag(+) ions from a 10, 20, 40, 60, and 100 nm AgNPs-coated PA66 surface was a function of the particles' size, number, and aging. Plasma pretreatment promoted both ionic and covalent interactions between AgNPs and the formed oxygen species on the fibers, favoring the deposition of smaller-diameter AgNPs that consequently showed better immediate and durable antimicrobial effects against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. Surprisingly, after 30 days of aging, a comparable bacterial growth inhibition was achieved for all of the fibers treated with AgNPs <100 nm in size. The Ag(+) in the coatings also favored the electrostatic stabilization of the plasma-induced functional groups on the PA66 surface, thereby retarding the aging process. At the same time, the size-related ratio (Ag(+)/Ag(0)) of the AgNPs between 40 and 60 nm allowed for the controlled release of Ag(+) rather than bulk silver. Overall, the results suggest that instead of reducing the size of the AgNPs, which is associated with higher toxicity, similar long-term effects can be achieved with larger NPs (40-60 nm), even in lower concentrations. Because the antimicrobial efficiency of AgNPs larger than 30 nm is mainly ruled by the release of Ag(+) over time and not by the size and number of the AgNPs, this parameter is crucial for the development of efficient antimicrobial coatings on plasma-treated surfaces and contributes to the safety and durability of clothing used in clinical settings.

  12. Synthesis, characterization and osteoblastic activity of polycaprolactone nanofibers coated with biomimetic calcium phosphate.

    PubMed

    Mavis, Bora; Demirtaş, Tolga T; Gümüşderelioğlu, Menemşe; Gündüz, Güngör; Colak, Uner

    2009-10-01

    Immersion of electrospun polycaprolactone (PCL) nanofiber mats in calcium phosphate solutions similar to simulated body fluid resulted in deposition of biomimetic calcium phosphate layer on the nanofibers and thus a highly bioactive novel scaffold has been developed for bone tissue engineering. Coatings with adequate integrity, favorable chemistry and morphology were achieved in less than 6h of immersion. In the coating solutions, use of lower concentrations of phosphate sources with respect to the literature values (i.e., 3.62 vs. 10 mM) was substantiated by a thermodynamic modeling approach. Recipe concentration combinations that were away from the calculated dicalcium phosphate phase stability region resulted in micron-sized calcium phosphates with native nanostructures. While the nano/microstructure formed by the deposited calcium phosphate layer is controlled by increasing the solution pH to above 6.5 and increasing the duration of immersion experimentally, the nanostructure imposed by the dimensions of the fibers was controlled by the polymer concentration (12% w/v), applied voltage (25 kV) and capillary tip to collector distance (35 cm). The deposited coating increased quantitatively by extending the soak up to 6h. On the other hand, the porosity values attained in the scaffolds were around 87% and the biomimetic coatings did not alter the nanofiber mat porosities negatively since the deposition continued along the fibers after the first 2h. Upon confirming the non-toxic nature of the electrospun PCL nanofiber mats, the effects of different nano/microstructures formed were evaluated by the osteoblastic activity. The levels of both alkaline phosphatase activity and osteocalcin were found to be higher in the coated PCL nanofibers than in the uncoated PCL nanofibers, indicating that biomimetic calcium phosphate on PCL nanofibers supports osteoblastic differentiation.

  13. A deep look into the spray coating process in real-time—the crucial role of x-rays

    NASA Astrophysics Data System (ADS)

    Roth, Stephan V.

    2016-10-01

    Tailoring functional thin films and coating by rapid solvent-based processes is the basis for the fabrication of large scale high-end applications in nanotechnology. Due to solvent loss of the solution or dispersion inherent in the installation of functional thin films and multilayers the spraying and drying processes are strongly governed by non-equilibrium kinetics, often passing through transient states, until the final structure is installed. Therefore, the challenge is to observe the structural build-up during these coating processes in a spatially and time-resolved manner on multiple time and length scales, from the nanostructure to macroscopic length scales. During installation, the interaction of solid-fluid interfaces and between the different layers, the flow and evaporation themselves determine the structure of the coating. Advanced x-ray scattering methods open a powerful pathway for observing the involved processes in situ, from the spray to the coating, and allow for gaining deep insight in the nanostructuring processes. This review first provides an overview over these rapidly evolving methods, with main focus on functional coatings, organic photovoltaics and organic electronics. Secondly the role and decisive advantage of x-rays is outlined. Thirdly, focusing on spray deposition as a rapidly emerging method, recent advances in investigations of spray deposition of functional materials and devices via advanced x-ray scattering methods are presented.

  14. Reactive Molecular Dynamics Investigations of Alkoxysilane Sol-Gel and Surface Coating Processes

    NASA Astrophysics Data System (ADS)

    Deetz, Joshua David

    The ability to generate nanostructured materials with tailored morphology or chemistry is of great technological interest. One proven method of generating metal-oxide materials, and chemically modifying metal-oxide surfaces is through the reactions of molecular building blocks known as alkoxysilanes. Alkoxysilanes are a class of chemicals which contain one or more organic alkoxy groups bonded to silicon atoms. Alkoxysilane (Si-O-R) chemical groups can undergo reactions to form bridges (Si-O-M) with metal oxides. Due to their ability to "attach" to metal-oxides through condensation reactions, alkoxysilanes have a number of interesting applications, such as: the generation of synthetic siloxane materials through the sol-gel process, and the formation of functionalized surface coatings on metal-oxide surfaces. Despite widespread study of sol-gel and surface coatings processes, it is difficult to predict the morphology of the final products due to the large number of process variables involved, such as precursor molecule structure, solvent effects, solution composition, temperature, and pH. To determine the influence of these variables on the products of sol-gel and coatings processes reactive molecular dynamics simulations are used. A reactive force field was used (ReaxFF) to allow the chemical bonds in simulation to dynamically form and break. The force field parameters were optimized using a parallel optimization scheme with a combination of experimental information, and density functional theory calculations. Polycondensation of alkoxysilanes in mixtures of alcohol and water were studied. Steric effects were observed to influence the rates of hydrolysis and condensation in solutions containing different precursor monomers. By restricting the access of nucleophiles to the central silicon atom, the nucleation rate of siloxanes can be controlled. The influence of solution precursor, water, and methanol composition on reaction rates was explored. It was determined that

  15. Polydopamine-Coated Manganese Complex/Graphene Nanocomposite for Enhanced Electrocatalytic Activity Towards Oxygen Reduction

    NASA Astrophysics Data System (ADS)

    Parnell, Charlette M.; Chhetri, Bijay; Brandt, Andrew; Watanabe, Fumiya; Nima, Zeid A.; Mudalige, Thilak K.; Biris, Alexandru S.; Ghosh, Anindya

    2016-08-01

    Platinum electrodes are commonly used electrocatalysts for oxygen reduction reactions (ORR) in fuel cells. However, this material is not economical due to its high cost and scarcity. We prepared an Mn(III) catalyst supported on graphene and further coated with polydopamine, resulting in superior ORR activity compared to the uncoated PDA structures. During ORR, a peak potential at 0.433 V was recorded, which is a significant shift compared to the uncoated material’s ‑0.303 V (both versus SHE). All the materials reduced oxygen in a wide pH range via a four-electron pathway. Rotating disk electrode and rotating ring disk electrode studies of the polydopamine-coated material revealed ORR occurring via 4.14 and 4.00 electrons, respectively. A rate constant of 6.33 × 106 mol‑1s‑1 was observed for the polydopamine-coated material–over 4.5 times greater than the uncoated nanocomposite and superior to those reported for similar carbon-supported metal catalysts. Simply integrating an inexpensive bioinspired polymer coating onto the Mn-graphene nanocomposite increased ORR performance significantly, with a peak potential shift of over +730 mV. This indicates that the material can reduce oxygen at a higher rate but with lower energy usage, revealing its excellent potential as an ORR electrocatalyst in fuel cells.

  16. Comparing graphene, carbon nanotubes, and superfine powdered activated carbon as adsorptive coating materials for microfiltration membranes.

    PubMed

    Ellerie, Jaclyn R; Apul, Onur G; Karanfil, Tanju; Ladner, David A

    2013-10-15

    Multi-walled carbon nanotubes (MWCNTs), nano-graphene platelets (NGPs), and superfine powdered activated carbon (S-PAC) were comparatively evaluated for their applicability as adsorptive coatings on microfiltration membranes. The objective was to determine which materials were capable of contaminant removal while causing minimal flux reduction. Methylene blue and atrazine were the model contaminants. When applied as membrane coatings, MWCNTs had minimal retention capabilities for the model contaminants, and S-PAC had the fastest removal. The membrane coating approach was also compared with a stirred vessel configuration, in which the adsorbent was added to a stirred flask preceding the membrane cell. Direct application of the adsorbent to the membrane constituted a greater initial reduction in permeate concentrations of the model contaminants than with the stirred flask setup. All adsorbents except S-PAC showed flux reductions less than 5% after application as thin-layer membrane coatings, and flux recovery after membrane backwashing was greater than 90% for all materials and masses tested.

  17. Long-term active antimicrobial coatings for surgical sutures based on silver nanoparticles and hyperbranched polylysine.

    PubMed

    Ho, Chau Hon; Odermatt, Erich K; Berndt, Ingo; Tiller, Joerg C

    2013-01-01

    The goal of this study was to develop a long-term active antimicrobial coating for surgical sutures. To this end, two water-insoluble polymeric nanocontainers based on hyperbranched polylysine (HPL), hydrophobically modified by either using glycidyl hexadecyl ether, or a mixture of stearoyl/palmitoyl chloride, were synthesized. Highly stabilized silver nanoparticles (AgNPs, 2-5 nm in size) were generated by dissolving silver nitrate in the modified HPL solutions in toluene followed by reduction with L-ascorbic acid. Poly(glycolic acid)-based surgical sutures were dip-coated with the two different polymeric silver nanocomposites. The coated sutures showed high efficacies of more than 99.5% reduction of adhesion of living Staphylococcus aureus cells onto the surface compared to the uncoated specimen. Silver release experiments were performed on the HPL-AgNP modified sutures by washing them in phosphate buffered saline for a period of 30 days. These coatings showed a constant release of silver ions over more than 30 days. After this period of washing, the sutures retained their high efficacies against bacterial adhesion. Cytotoxicity tests using L929 mouse fibroblast cells showed that the materials are basically non-cytotoxic.

  18. Polydopamine-Coated Manganese Complex/Graphene Nanocomposite for Enhanced Electrocatalytic Activity Towards Oxygen Reduction

    PubMed Central

    Parnell, Charlette M.; Chhetri, Bijay; Brandt, Andrew; Watanabe, Fumiya; Nima, Zeid A.; Mudalige, Thilak K.; Biris, Alexandru S.; Ghosh, Anindya

    2016-01-01

    Platinum electrodes are commonly used electrocatalysts for oxygen reduction reactions (ORR) in fuel cells. However, this material is not economical due to its high cost and scarcity. We prepared an Mn(III) catalyst supported on graphene and further coated with polydopamine, resulting in superior ORR activity compared to the uncoated PDA structures. During ORR, a peak potential at 0.433 V was recorded, which is a significant shift compared to the uncoated material’s −0.303 V (both versus SHE). All the materials reduced oxygen in a wide pH range via a four-electron pathway. Rotating disk electrode and rotating ring disk electrode studies of the polydopamine-coated material revealed ORR occurring via 4.14 and 4.00 electrons, respectively. A rate constant of 6.33 × 106 mol−1s−1 was observed for the polydopamine-coated material–over 4.5 times greater than the uncoated nanocomposite and superior to those reported for similar carbon-supported metal catalysts. Simply integrating an inexpensive bioinspired polymer coating onto the Mn-graphene nanocomposite increased ORR performance significantly, with a peak potential shift of over +730 mV. This indicates that the material can reduce oxygen at a higher rate but with lower energy usage, revealing its excellent potential as an ORR electrocatalyst in fuel cells. PMID:27528439

  19. Hyaluronic acid-coated liposomes for active targeting of gemcitabine.

    PubMed

    Arpicco, Silvia; Lerda, Carlotta; Dalla Pozza, Elisa; Costanzo, Chiara; Tsapis, Nicolas; Stella, Barbara; Donadelli, Massimo; Dando, Ilaria; Fattal, Elias; Cattel, Luigi; Palmieri, Marta

    2013-11-01

    The aim of this work was the preparation, characterization, and preliminary evaluation of the targeting ability toward pancreatic adenocarcinoma cells of liposomes containing the gemcitabine lipophilic prodrug [4-(N)-lauroyl-gemcitabine, C12GEM]. Hyaluronic acid (HA) was selected as targeting agent since it is biodegradable, biocompatible, and can be chemically modified and its cell surface receptor CD44 is overexpressed on various tumors. For this purpose, conjugates between a phospholipid, the 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), and HA of two different low molecular weights 4800 Da (12 disaccharidic units) and 12,000 Da (32 disaccharidic units), were prepared, characterized, and introduced in the liposomes during the preparation. Different liposomal formulations were prepared and their characteristics were analyzed: size, Z potential, and TEM analyses underline a difference in the HA-liposomes from the non-HA ones. In order to better understand the HA-liposome cellular localization and to evaluate their interaction with CD44 receptor, confocal microscopy studies were performed. The results demonstrate that HA facilitates the recognition of liposomes by MiaPaCa2 cells (CD44(+)) and that the uptake increases with increase in the polymer molecular weight. Finally, the cytotoxicity of the different preparations was evaluated and data show that incorporation of C12GEM increases their cytotoxic activity and that HA-liposomes inhibit cell growth more than plain liposomes. Altogether, the results demonstrate the specificity of C12GEM targeting toward CD44-overexpressing pancreatic adenocarcinoma cell line using HA as a ligand.

  20. Effect of membrane-associated f1 bacteriophage coat protein upon the activity of Escherichia coli phosphatidylserine synthetase.

    PubMed Central

    Chamberlain, B K; Webster, R E

    1978-01-01

    The effects of insertion of the major coat protein of f1 bacteriophage into Escherichia coli membranes were investigated under conditions allowing in vivo analysis of phosphatidylserine synthesis. An E. coli strain possessing a temperature-sensitive phosphatidylserine decarboxylase was utilized under conditions in which the decarboxylase activity was reduced but nonlethal. The presence of the coat protein in the host membranes inhibits the activity of the phosphatidylserine synthetase and perhaps affects the activity of the phosphatidylserine decarboxylase. PMID:211116

  1. Dip process thermal-barrier coatings for superalloys. Final report 1 Jul 79-30 Jun 80

    SciTech Connect

    Allam, I.M.; Bartlett, R.W.; Krishnan, G.N.

    1980-06-30

    A new technique of developing thermal-barrier coatings for superalloys has been investigated. It involves hot dipping of superalloy samples into a molten bath of low melting Ce-Co or Ce-Ni alloy. By internally oxidizing these coatings, it is possible to obtain a duplex with a CeO2-rich oxide scale as the outer layer (thermal barrier) and an inner layer composite of fine cerium oxide particles dispersed in a matrix of Ni(Co)CrAl. This inner layer, or subscale, grades into the superalloy. Appropriate heat treatment can produce recrystallized CeO2 particles in the subscale that should improve adherence of the oxide scale to the subscale and substrate superalloy. The coating process does involve limited reaction between the coating alloy and superalloy. The thickness of this interaction zone can be controlled and compensated for in the design (cross section) of the superalloy component.

  2. Superhydrophobic and conductive properties of carbon nanotubes/polybenzoxazine nanocomposites coated ramie fabric prepared by solution-immersion process

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Yan, Hongqiang; Fang, Zhengping; E, Yuping; Wu, Tao; Chen, Fei

    2014-08-01

    Nanocomposites coating consisting of pristine multiwall carbon nanotubes (MWNTs) and polybenzoxazine has been constructed onto ramie fabric through solution-immersion process. The adsorbed nanocomposites coating is a hierarchical three-dimensional interpenetrating network structure, and the surface coverage and density increase substantially with increasing repeated immersing cycles. Measurements of the superhydrophobicity and conductivity for the coated ramie fabrics show that the highest water contact angle reaches 152°, the lowest water sliding angle reaches 3°, and the corresponding sheet resistance is 3410 Ω sq-1, which shows strong dependency on the number of repeated immersing cycles and concentration of MWNTs suspension. This work provides a facile pathway to design and fabricate nanocomposites coated natural cellulosic fabric for superhydrophobic and conductive applications.

  3. Development of an Innovative Laser-Assisted Coating Process for Extending Lifetime of Metal Casting Dies. Final Report

    SciTech Connect

    Madhav Rao Gonvindaraju

    1999-10-18

    Die casting dies used in the metal casting industry fail due to thermal fatigue cracking accompanied by the presence of residual tensile stresses, corrosion, erosion and wear of die surfaces. This phase 1 SBIR Final Report summarize Karta Technologies research involving the development of an innovative laser coating technology for metal casting dies. The process involves depositing complex protective coatings of nanocrystalline powders of TiC followed by a laser shot peening. The results indicate a significant improvement in corrosion and erosion resistance in molten aluminum for H13 die casting die steels. The laser-coated samples also showed improved surface finish, a homogeneous and uniform coating mircrostructure. The technology developed in this research can have a significant impact on the casting industry by saving the material costs involved in replacing dies, reducing downtime and improving the quality.

  4. Synthesis of aluminum-rich coatings on new high-temperature cast austenitic steel CF8C-Plus by a pack cementation process

    NASA Astrophysics Data System (ADS)

    Hall, Alex Keith

    2011-12-01

    In this research, a pack cementation process is developed for coating the newly developed cast austenitic steel CF8C-Plus. The developed coating process is capable of producing pack particle free coatings on large fatigue test specimens in a horizontal laboratory tube furnace as well as smaller oxidation and creep test samples. Several methods for the production of the pack powder free Al-rich coating are presented and evaluated for samples of both sizes. The developed coating is intended to compete with coatings of a similar quality produced with chemical vapor deposition and slurry coating methods. Additionally, because CF8C-Plus has only recently become available there is currently no available data on the effect of the fabrication of an Al-rich coating on the substrates properties. This research used advanced characterization methods to evaluate the coating surface and cross-sectional features. These methods include scanning electron microscopy, X-ray diffraction, electron probe microanalysis and energy dispersive spectroscopy analysis. This is the first time that this information has been made available to the scientific community. Also, the oxidation performance of the coating will be tested and compared to other coatings developed with CVD and slurry coating methods and the preliminary results of the effect of the coating on the alloys fatigue performance will be presented.

  5. TiO2-coated mesoporous carbon: conventional vs. microwave-annealing process.

    PubMed

    Coromelci-Pastravanu, Cristina; Ignat, Maria; Popovici, Evelini; Harabagiu, Valeria

    2014-08-15

    The study of coating mesoporous carbon materials with titanium oxide nanoparticles is now becoming a promising and challenging area of research. To optimize the use of carbon materials in various applications, it is necessary to attach functional groups or other nanostructures to their surface. The combination of the distinctive properties of mesoporous carbon materials and titanium oxide is expected to be applied in field emission displays, nanoelectronic devices, novel catalysts, and polymer or ceramic reinforcement. But, their synthesis is still largely based on conventional techniques, such as wet impregnation followed by chemical reduction of the metal nanoparticle precursors, which takes time and money. The thermal heating based techniques are time consuming and often lack control of particle size and morphology. Hence, since there is a growing interest in microwave technology, an alternative way of power input into chemical reactions through dielectric heating is the use of microwaves. This work is focused on the advantages of microwave-assisted synthesis of TiO2-coated mesoporous carbon over conventional thermal heating method. The reviewed studies showed that the microwave-assisted synthesis of such composites allows processes to be completed within a shorter reaction time allowing the nanoparticles formation with superior properties than that obtained by conventional method.

  6. Solution-process coating of vertical ZnO nanowires with ferroelectrics.

    PubMed

    Kawasaki, Susumu; Fan, Hong Jin; Catalan, Gustau; Morrison, Finlay D; Tatsuta, Toshiaki; Tsuji, Osamu; Scott, James F

    2008-09-17

    We have developed a modified misted deposition process by combining substrate and mist heating for the deposition of ferroelectrics on 3D nanostructures. Arrays of vertical ZnO nanowires, sputter coated with Pd bottom electrodes, are used as the substrate. Scanning electron microscopy investigations show that conformal coating of ferroelectric Pb(Zr,Ti)O(3) (PZT) with good step coverage is obtained at deposition temperatures above 140 °C. The substrate heating also eliminates the common 'bundling' problem of the nanowire arrays. On the basis of data on x-ray diffraction, energy dispersive x-ray spectroscopy, and P-E hysteresis of PZT films on flat substrates, we obtain the optimum substrate temperature window to be 180-220 °C, in terms of best step coverage and an evident ferroelectricity. This is a significant step towards the end-goal of fully integrated ZnO nanowires with ferroelectric capacitors, which may be useful for the light-emitting applications of ZnO.

  7. Nitroxide polymer networks formed by Michael addition: on site-cured electrode-active organic coating.

    PubMed

    Ibe, Takeshi; Frings, Rainer B; Lachowicz, Artur; Kyo, Soichi; Nishide, Hiroyuki

    2010-05-28

    Highly and homogeneously crosslinked poly(beta-ketoester) networks densely bearing robust nitroxide radicals were prepared via a click-type and stepwise Michael polyaddition. A half-battery cell composed of the thermally-cured radical network coatings displayed a rapid, reversible, and almost stoichiometric redox-activity even with a thickness of ca. 10 mum, which may be applicable as the electrode of organic-based rechargeable devices.

  8. Effect of active edible coatings made by basil seed gum and thymol on oil uptake and oxidation in shrimp during deep-fat frying.

    PubMed

    Khazaei, Naimeh; Esmaiili, Mohsen; Emam-Djomeh, Zahra

    2016-02-10

    The effect of active coating treatments on oil uptake, moisture loss, lipid oxidation, texture, color, and sensory evaluation of shrimp after deep-fat frying process was investigated. Compared with the uncoated samples, coating treatments decreased the oil uptake and moisture loss of fried shrimp by 34.50 and 13.9%, respectively. Fried shrimp samples were analyzed for peroxide value (PV) and thiobarbituric acid (TBA). The most reduction in lipid oxidation (46.4% for PV and 40.8% for TBA) was observed when shrimp samples were coated with CS4 (containing 10% thyme), while the control samples had the highest values of PV and TBA after deep-fat frying process. Coated fried samples had significantly lower toughness and stiffness than control samples (P<0.05). In terms of sensory evaluation, there was no significant difference in color, smell, and taste among the treatments (P>0.05). However, for the texture, juiciness, chewiness, and overall acceptability, coated fried samples had higher scores than control.

  9. Antibacterial activity and increased bone marrow stem cell functions of Zn-incorporated TiO2 coatings on titanium.

    PubMed

    Hu, H; Zhang, W; Qiao, Y; Jiang, X; Liu, X; Ding, C

    2012-02-01

    In this work, zinc was incorporated into TiO2 coatings on titanium by plasma electrolytic oxidation to obtain the implant with good bacterial inhibition ability and bone-formability. The porous and nanostructured Zn-incorporated TiO2 coatings are built up from pores smaller than 5 μm and grains 20-100 nm in size, in which the element Zn exists as ZnO. The results obtained from the antibacterial studies suggest that the Zn-incorporated TiO2 coatings can greatly inhibit the growth of both Staphylococcus aureus and Escherichia coli, and the ability to inhibit bacteria can be improved by increasing the Zn content in the coatings. Moreover, the in vitro cytocompatibility evaluation demonstrates that the adhesion, proliferation and differentiation of rat bone marrow stem cells (bMSC) on Zn-incorporated coatings are significantly enhanced compared with Zn-free coating and commercially pure Ti plate, and no cytotoxicity appeared on any of the Zn-incorporated TiO2 coatings. Moreover, bMSC express higher level of alkaline phosphatase activity on Zn-incorporated TiO2 coatings and are induced to differentiate into osteoblast cells. The better antibacterial activity, cytocompatibility and the capability to promote bMSC osteogenic differentiation of Zn-incorporated TiO2 coatings may be attributed to the fact that Zn ions can be slowly and constantly released from the coatings. In conclusion, innovative Zn-incorporated TiO2 coatings on titanium with excellent antibacterial activity and biocompatibility are promising candidates for orthopedic and dental implants.

  10. Process optimization for a 3D optical coupler and waveguide fabrication on a single substrate using buffer coat material

    NASA Astrophysics Data System (ADS)

    Summitt, Chris; Wang, Sunglin; Johnson, Lee; Zaverton, Melissa; Ge, Tao; Milster, Tom; Takashima, Yuzuru

    2015-03-01

    We have developed a hybrid lithography process necessary to fabricate a vertical optical coupler and an array of waveguide structures using the same buffer coat material on a single substrate. A virtual vernier scale built into the process enables precise alignment of both structures.

  11. Press-hardening of zinc coated steel - characterization of a new material for a new process

    NASA Astrophysics Data System (ADS)

    Kurz, T.; Larour, P.; Lackner, J.; Steck, T.; Jesner, G.

    2016-11-01

    Press-hardening of zinc-coated PHS has been limited to the indirect process until a pre-cooling step was introduced before the hot forming to prevent liquid metal embrittlement. Even though that's only a minor change in the process itself it does not only eliminate LME, but increases also the demands on the base material especially in terms of hardenability or phase transformations at temperatures below 700 °C in general. This paper deals with the characterization of a modified zinc-coated material for press-hardening with pre-cooling that assures a robust process. The pre-cooling step itself and especially the transfer of the blank in the hot-forming die is more demanding than the standard 22MnB5 can stand to ensure full hardenability. Therefore the transformation behavior of the modified material is shown in CCT and TTT diagrams. Of the same importance are the changed hot forming temperature and flow curves for material at lower temperatures than typically used in direct hot forming. The resulting mechanical properties after hardening from tensile testing and bending tests are shown in detail. Finally some results from side impact crash tests and correlations of the findings with mechanical properties such as fracture elongation, tensile strength, VDA238 bending angle at maximum force as well as postuniform bending slope are given as well. Fracture elongation is shown to be of little help for damage prediction in side impact crash. Tensile strength and VDA bending properties enable however some accurate prediction of the PHS final damage behavior in bending dominated side impact load case.

  12. Establishment of Epithelial Attachment on Titanium Surface Coated with Platelet Activating Peptide

    PubMed Central

    Sugawara, Shiho; Maeno, Masahiko; Lee, Cliff; Nagai, Shigemi; Kim, David M.; Da Silva, John; Kondo, Hisatomo

    2016-01-01

    The aim of this study was to produce epithelial attachment on a typical implant abutment surface of smooth titanium. A challenging complication that hinders the success of dental implants is peri-implantitis. A common cause of peri-implantitis may results from the lack of epithelial sealing at the peri-implant collar. Histologically, epithelial sealing is recognized as the attachment of the basement membrane (BM). BM-attachment is promoted by activated platelet aggregates at surgical wound sites. On the other hand, platelets did not aggregate on smooth titanium, the surface typical of the implant abutment. We then hypothesized that epithelial BM-attachment was produced when titanium surface was modified to allow platelet aggregation. Titanium surfaces were coated with a protease activated receptor 4-activating peptide (PAR4-AP). PAR4-AP coating yielded rapid aggregation of platelets on the titanium surface. Platelet aggregates released robust amount of epithelial chemoattractants (IGF-I, TGF-β) and growth factors (EGF, VEGF) on the titanium surface. Human gingival epithelial cells, when they were co-cultured on the platelet aggregates, successfully attached to the PAR4-AP coated titanium surface with spread laminin5 positive BM and consecutive staining of the epithelial tight junction component ZO1, indicating the formation of complete epithelial sheet. These in-vitro results indicate the establishment of epithelial BM-attachment to the titanium surface. PMID:27741287

  13. Study of Aerospace Materials, Coatings, Adhesions and Processes. Aircraft Icing Processes. Volume 1.

    DTIC Science & Technology

    1984-09-14

    AP A160 413 STUDY OF AEROSPACE MATERIALS CATIS AD|SIOS A - PROCESSES AIRCRAFT IC.. (UI INSTITUbO NACIONAL DE TECNICA AEROESPACIAL MORID ISPAIN) E I...Approved for public release; distribution unlimited. Prepared for INSTITTTTO NACIONAL DE TECNICA AEROESPACIAL "Esteban Terradas". Torrejdn de Ardoz...ADDRESS il0. PROGRAM ELEMENT. PROJECT, TASKC Thstituto Naciorial Tecnica Aeroespacial Dto. Aerodindmica y Navegabilidad 2301 / D1 Torrejcn de Ardoz

  14. An ecotoxicological study on tin- and bismuth-catalysed PDMS based coatings containing a surface-active polymer.

    PubMed

    Pretti, Carlo; Oliva, Matteo; Mennillo, Elvira; Barbaglia, Martina; Funel, Marco; Reddy Yasani, Bhaskar; Martinelli, Elisa; Galli, Giancarlo

    2013-12-01

    Novel films were prepared by condensation curing reaction of a poly(dimethyl siloxane) (PDMS) matrix with bismuth neodecanoate and dibutyltin diacetate catalysts. An ecotoxicological study was performed on the leachates of the coatings using the bacterium Vibrio fischeri, the unicellular alga Dunaliella tertiolecta, the crustacean Artemia salina and the fish Sparus aurata (larvae) as testing organisms. A copper-based self-polishing commercial paint was also tested as reference. The results showed that the tin-catalysed coatings and the copper paint were highly toxic against at least two of the four test organisms, whereas bismuth-catalysed coatings did not show any toxic effect. Moreover, the same biological assessment was also carried out on PDMS coatings containing a surface-active fluorinated polymer. The toxicity of the entire polymeric system resulted only from the tin catalyst used for the condensation curing reaction, as the bismuth catalysed coatings incorporating the surface-active polymer remained atoxic toward all the tested organisms.

  15. A Study of Pack Aluminizing Process for NiCrAlY Coatings Using Response Surface Methodology

    NASA Astrophysics Data System (ADS)

    Gao, Feng; Huang, Xiao; Liu, Rong; Yang, Qi

    2014-01-01

    Aluminizing process is widely used to provide additional Al deposition onto superalloy surface for enhanced oxidation and corrosion resistance. In this research, an aluminizing process—pack cementation process, is used to deposit Al onto the surface of NiCrAlY coatings for increasing environmental protection. The experiment is designed using Box-Behnken approach, in which three parameters, the Al content, Ni content of the pack powder, and the temperature of the process, are selected as factors; and the thickness and Al/Ni ratio of the coatings are selected as responses. The effects of the factors on the responses are analyzed and modeled empirically. It is found that these empirical models correlate well with the results from additional sets of experiment. These models can be used to produce aluminized NiCrAlY coatings with specific thicknesses and Al/Ni ratios.

  16. Parametric Appraisal of Process Parameters for Adhesion of Plasma Sprayed Nanostructured YSZ Coatings Using Taguchi Experimental Design

    PubMed Central

    Mantry, Sisir; Mishra, Barada K.; Chakraborty, Madhusudan

    2013-01-01

    This paper presents the application of the Taguchi experimental design in developing nanostructured yittria stabilized zirconia (YSZ) coatings by plasma spraying process. This paper depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on various process parameters, and effect of those process parameters on performance output has been studied using Taguchi's L16 orthogonal array design. Particle velocities prior to impacting the substrate, stand-off-distance, and particle temperature are found to be the most significant parameter affecting the bond strength. To achieve retention of nanostructure, molten state of nanoagglomerates (temperature and velocity) has been monitored using particle diagnostics tool. Maximum adhesion strength of 40.56 MPa has been experimentally found out by selecting optimum levels of selected factors. The enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nanozones. PMID:24288490

  17. COATED CARBON ELEMENT FOR USE IN NUCLEAR REACTORS AND THE PROCESS OF MAKING THE ELEMENT

    DOEpatents

    Pyle, R.J.; Allen, G.L.

    1963-01-15

    S>This patent relates to a carbide-nitride-carbide coating for carbon bodies that are to be subjected to a high temperature nuclear reactor atmosphere, and a method of applying the same. This coating is a highly efficient diffusion barrier and protects the C body from corrosion and erosion by the reactor atmosphere. Preferably, the innermost coating is Zr carbide, the middle coatlng is Zr nitride, and the outermost coating is a mixture of Zr and Nb carbide. The nitride coating acts as a diffusion barrier, while the innermost carbide bonds the nitride to the C body and prevents deleterious reaction between the nitride and C body. The outermost carbide coating protects the nitride coating from the reactor atmosphere. (AEC)

  18. Understanding the effects of process parameters on the properties of cold gas dynamic sprayed pure titanium coatings

    NASA Astrophysics Data System (ADS)

    Wong, Wilson

    The cold gas dynamic spraying of commercially pure titanium coatings was investigated. Specifically, the relationship between several key cold spray parameters on the quality of the resulting coatings was studied in order to gain a more thorough understanding of the cold spray process. To achieve this goal, three distinct investigations were performed. The first part of the investigation focussed on the effect of propelling gas, particularly helium and nitrogen, during the cold spraying of titanium coatings. Coatings were characterised by SEM and were evaluated for their deposition efficiency (DE), microhardness, and porosity. In selected conditions, three particle velocities were investigated such that for each condition, the propelling gasses temperature and pressure were attuned to attain similar particle velocities for each gas. In addition, a thick and fully dense cold sprayed titanium coating was achieved with optimised spray parameters and nozzle using helium. The corresponding average particle velocity was 1173 m/s. The second part of the investigation studied the effect of particle morphology (spherical, sponge, and irregular) and size distributions (mean particle sizes of 20, 29, and 36 mum) of commercially pure titanium on the mechanical properties of the resulting cold sprayed coatings. Numerous powder and coating characterisations were performed. From these data, semi-empirical flow (stress-strain) curves were generated based on the Johnson-Cook plasticity model which could be used as a measure of cold sprayability. Cold sprayability can be defined as the ease with which a powder can be cold sprayed. It was found that the sponge and irregular commercially pure titanium powders had higher oxygen content, poorer powder flowability, higher compression ratio, lower powder packing factor, and higher average particle impact velocities compared to the spherical powders. XRD results showed no new phases present when comparing the various feedstock powders to

  19. In vitro testing of Nd:YAG laser processed calcium phosphate coatings.

    PubMed

    De Carlos, A; Lusquiños, F; Pou, J; León, B; Pérez-Amor, M; Driessens, F C M; Hing, K; Best, S; Bonfield, W

    2006-11-01

    Nd:YAG laser cladding is a new method for deposition of a calcium phosphate onto metallic surfaces of interest in implantology. The aim of this study was to compare the biologic response of MG-63 human osteoblast-like cells grown on Ti-6Al-4V substrates coated with a calcium phosphate layer applied using different methods: plasma spraying as reference material and Nd:YAG laser cladding as test material. Tissue culture polystyrene was used as negative control. The Nd:YAG laser clad material showed a behaviour similar to the reference material, plasma spray, respective to cell morphology (SEM observations), cell proliferation (AlamarBlue assay) and cytotoxicity of extracts (MTT assay). Proliferation, as measured by the AlamarBlue assay, showed little difference in the metabolic activity of the cells on the materials over an 18 day culture period. There were no significant differences in the cellular growth response on the test material when compared to the ones exhibited by the reference material. In the solvent extraction test all the extracts had some detrimental effect on cellular activity at 100% concentration, although cells incubated in the test material extract showed a proliferation rate similar to that of the reference material. To better understand the scope of these results it should be taken into account that the Nd:YAG clad coating has recently been developed. The fact that its in vitro performance is comparable to that produced by plasma spray, a material commercially available for more than ten years, indicates that this new laser based method could be of commercial interest in the near future.

  20. A Novel Single-Step Surface-Treatment Process for Forming Cr-Nitride Coatings on Steels

    NASA Astrophysics Data System (ADS)

    Lu, X. J.; Xiang, Z. D.

    2017-02-01

    A novel single-step surface-treatment process is demonstrated for forming Cr-nitride coatings on steels. The process was carried out at 1327 K (1100 °C) for two steel grades with differing carbon concentrations. For steel grade with 0.42 to 0.5C (wt pct), the coatings formed consisted of an outer Cr2N layer and an inner Cr-carbide layer with a Cr-enriched interdiffusion zone underneath. However, for steel grade with C ≤ 0.17 wt pct, the inner Cr-carbide layer was absent.

  1. 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

  2. Optimization Control of the Color-Coating Production Process for Model Uncertainty.

    PubMed

    He, Dakuo; Wang, Zhengsong; Yang, Le; Mao, Zhizhong

    2016-01-01

    Optimized control of the color-coating production process (CCPP) aims at reducing production costs and improving economic efficiency while meeting quality requirements. However, because optimization control of the CCPP is hampered by model uncertainty, a strategy that considers model uncertainty is proposed. Previous work has introduced a mechanistic model of CCPP based on process analysis to simulate the actual production process and generate process data. The partial least squares method is then applied to develop predictive models of film thickness and economic efficiency. To manage the model uncertainty, the robust optimization approach is introduced to improve the feasibility of the optimized solution. Iterative learning control is then utilized to further refine the model uncertainty. The constrained film thickness is transformed into one of the tracked targets to overcome the drawback that traditional iterative learning control cannot address constraints. The goal setting of economic efficiency is updated continuously according to the film thickness setting until this reaches its desired value. Finally, fuzzy parameter adjustment is adopted to ensure that the economic efficiency and film thickness converge rapidly to their optimized values under the constraint conditions. The effectiveness of the proposed optimization control strategy is validated by simulation results.

  3. Optimization Control of the Color-Coating Production Process for Model Uncertainty

    PubMed Central

    He, Dakuo; Wang, Zhengsong; Yang, Le; Mao, Zhizhong

    2016-01-01

    Optimized control of the color-coating production process (CCPP) aims at reducing production costs and improving economic efficiency while meeting quality requirements. However, because optimization control of the CCPP is hampered by model uncertainty, a strategy that considers model uncertainty is proposed. Previous work has introduced a mechanistic model of CCPP based on process analysis to simulate the actual production process and generate process data. The partial least squares method is then applied to develop predictive models of film thickness and economic efficiency. To manage the model uncertainty, the robust optimization approach is introduced to improve the feasibility of the optimized solution. Iterative learning control is then utilized to further refine the model uncertainty. The constrained film thickness is transformed into one of the tracked targets to overcome the drawback that traditional iterative learning control cannot address constraints. The goal setting of economic efficiency is updated continuously according to the film thickness setting until this reaches its desired value. Finally, fuzzy parameter adjustment is adopted to ensure that the economic efficiency and film thickness converge rapidly to their optimized values under the constraint conditions. The effectiveness of the proposed optimization control strategy is validated by simulation results. PMID:27247563

  4. Finite element modelling of process-integrated powder coating by radial axial rolling of rings

    NASA Astrophysics Data System (ADS)

    Frischkorn, J.; Kebriaei, R.; Reese, S.; Moll, H.; Theisen, W.; Husmann, T.; Meier, H.

    2011-05-01

    The process-integrated powder coating by radial axial rolling of rings represents a new hybrid production technique applied in the manufacturing of large ring-shaped work pieces with functional layers. It is thought to break some limitations that come along with the hot isostatic pressing (HIP) which is used nowadays to apply the powdery layer material onto the rolled substrate ring. Within the new process the compaction of the layer material is integrated into the ring rolling and HIP becomes dispensable. Following this approach the rolling of such compound rings brings up some new challenges. The volume of a solid ring stays nearly constant during the rolling. This behaviour can be exploited to determine the infeed of the rollers needed to reach the desired ring shape. Since volume consistency cannot be guaranteed for the rolling of a compound ring the choice of appropriate infeed of the rollers is still an open question. This paper deals with the finite element (FE) simulation of this new process. First, the material model that is used to describe the compaction of the layer material is shortly reviewed. The main focus of the paper is then put on a parameterized FE ring rolling model that incorporates a control system in order to stabilize the process. Also the differences in the behaviour during the rolling stage between a compound and a solid ring will be discussed by means of simulation results.

  5. Finite element modelling of process-integrated powder coating by radial axial rolling of rings

    SciTech Connect

    Frischkorn, J.; Kebriaei, R.; Reese, S.; Moll, H.; Theisen, W.; Husmann, T.; Meier, H.

    2011-05-04

    The process-integrated powder coating by radial axial rolling of rings represents a new hybrid production technique applied in the manufacturing of large ring-shaped work pieces with functional layers. It is thought to break some limitations that come along with the hot isostatic pressing (HIP) which is used nowadays to apply the powdery layer material onto the rolled substrate ring. Within the new process the compaction of the layer material is integrated into the ring rolling and HIP becomes dispensable. Following this approach the rolling of such compound rings brings up some new challenges. The volume of a solid ring stays nearly constant during the rolling. This behaviour can be exploited to determine the infeed of the rollers needed to reach the desired ring shape. Since volume consistency cannot be guaranteed for the rolling of a compound ring the choice of appropriate infeed of the rollers is still an open question. This paper deals with the finite element (FE) simulation of this new process. First, the material model that is used to describe the compaction of the layer material is shortly reviewed. The main focus of the paper is then put on a parameterized FE ring rolling model that incorporates a control system in order to stabilize the process. Also the differences in the behaviour during the rolling stage between a compound and a solid ring will be discussed by means of simulation results.

  6. High-frequency eddy current based impedance spectroscopy for characterization of the percolation process of wet conductive coatings

    NASA Astrophysics Data System (ADS)

    Patsora, Iryna; Hillmann, Susanne; Heuer, Henning; Foos, Bryan C.; Calzada, Juan G.

    2015-03-01

    Coatings based on wet particles containing pastes are currently used in many industries, such as automotive, aircraft and/or wind-power plants, to protect carbon-fiber reinforced plastic against damages caused by electrical effects, such as a lightning strike. In order to understand and control the percolation behavior during the drying, a non-contact Eddy Current based Impedance Spectroscopy can be used. This technique can be applied in the wet state of the coating and it works non-destructively. Percolation behaviors of the wet conductive coatings are strongly affected by the type of particles used as a filling and the thickness of the coating. Experimental results of Eddy Current measurements on wet conductive coatings based on different conductive particles and deposited with different thicknesses are discussed. Based on High-Frequency Eddy Current measurements, a prognosis of the coating parameters after final curing during the wet state becomes conceivable. This, for example, offers a wide opportunity for process control and repairs.

  7. THE SIZE AND SURFACE COATING OF NANOSILVER DIFFERENTIALLY AFFECTS BIOLOGICAL ACTIVITY IN BLOOD BRAIN BARRIER (RBEC4) CELLS.

    EPA Science Inventory

    Linking the physical properties of nanoparticles with differences in their biological activity is critical for understanding their potential toxicity and mode of action. The influence of aggregate size, surface coating, and surface charge on nanosilver's (nanoAg) movement through...

  8. Analyses of Antibacterial Activity and Cell Compatibility of Titanium Coated with a Zr–C–N Film

    PubMed Central

    Chang, Yin-Yu; Huang, Heng-Li; Lai, Chih-Ho; Hsu, Jui-Ting; Shieh, Tzong-Ming; Wu, Aaron Yu-Jen; Chen, Chao-Ling

    2013-01-01

    Objective The purpose of this study was to verify the antibacterial performance and cell proliferation activity of zirconium (Zr)–carbon (C)–nitride (N) coatings on commercially pure titanium (Ti) with different C contents. Materials and Methods Reactive nitrogen gas (N2) with and without acetylene (C2H2) was activated by Zr plasma in a cathodic-arc evaporation system to deposit either a zirconium nitride (ZrN) or a Zr–C–N coating onto Ti plates. The bacterial activity of the coatings was evaluated against Staphylococcus aureus with the aid of SYTO9 nucleic acid staining and scanning electron microscopy (SEM). Cell compatibility, mRNA expression, and morphology related to human gingival fibroblasts (HGFs) on the coated samples were also determined by using the MTT assay, reverse transcriptase–polymerase chain reaction, and SEM. Results The Zr–C–N coating with the highest C content (21.7 at%) exhibited the lowest bacterial preservation (P<0.001). Biological responses including proliferation, gene expression, and attachment of HGF cells to ZrN and Zr–C–N coatings were comparable to those of the uncoated Ti plate. Conclusions High-C-content Zr–C–N coatings not only provide short-term antibacterial activity against S. aureus but are also biocompatible with HGF cells. PMID:23431391

  9. Platelet activation of platelet concentrates derived from buffy coat and apheresis methods.

    PubMed

    Ali, Soleimany Ferizhandy

    2011-02-01

    Preparation for storage may cause platelet activation. The quality of platelet concentrates plays an important role in transfusion therapy. Platelet concentrates are produced by different centrifugation methods; buffy coat (buffy coat-derived platelet concentrates-BC) and plateletpheresis (apheresis-derived platelet concentrates-APC). Their quality was assessed using the following parameters: platelet, WBC and RBC counts pH, volume, platelet factor 4 (PF4) and Annexin V. The present paper compares the quality of both platelet preparations in vitro. In this experimental study, 30 platelet concentrates were harvested with the Haemonetics MCS plus and 30 units via the buffy coat (BC) method. The percentages of Annexin V expression, PF4 levels, platelet, WBC and RBC counts, pH and volume were measure immediately after collection and after 3 days of storage. During storage for up to 3 days, BC units displayed, no significant pH or RBC, difference in comparison with apheresis preparations (p>0.05). During storage for up to 3 days, BC units displayed a significant increase in the PF4 and Annexin V expression, compared to the apheresis preparations on day three (p<0.05). The kinetics of PF4 and Annexin V levels are influenced by the method used to prepare platelets for storage. The different levels of PF4 and Annexin V in BCs and APCs clearly demonstrates a progressive activation of BC platelets exceeding that of APC. However, in vivo studies should be performed to confirm these findings.

  10. Template-activated strategy toward one-step coating silica colloidal microspheres with sliver.

    PubMed

    Wang, Ke; Zhang, Xiaoli; Niu, Chunyu; Wang, Yongqiang

    2014-01-22

    Template-activated strategy was developed to coat silica (SiO2) colloidal microspheres with silver in one step, based on one-pot hydrothermal treatment of silver nitrate, PVP (poly(vinyl pyrrolidone)), and SiO2 colloidal microspheres in ammonia solution. In our reaction system, the surface of SiO2 colloidal microspheres was continually activated with negative-charged SiO(-) groups in ammonia solution, which accumulated [Ag(NH3)2](+) or Ag(+) ions around the SiO2 colloidal microspheres through electrostatic attraction; thereafter these ions could be reduced into Ag nanoparticles in situ by the weak reducer PVP in the solution, and then acted as seeds for the subsequent complete silver coating with the reaction proceeding. Therefore, the traditional three steps for complete silver coating, including prior surface modification, seeding, and subsequent growing, were effectively integrated into one step. The experimental results exhibited that perfect SiO2/Ag core/shell composite microspheres were successfully synthesized through optimizing the reaction parameters like the solvent ingredient, reducer, and the reaction temperature. Additionally, these obtained uniform composite microspheres were further used as SERS substrate by using R6G and thiram as probe molecules, and showed excellent trace detection of these organic chemicals in solution.

  11. Cloud Condensation Nucleus Activity of calcite and calcite coated with model humic and fulvic acids

    NASA Astrophysics Data System (ADS)

    Hatch, C. D.; Gierlus, K. M.; Schuttlefield, J. D.; Grassian, V. H.

    2007-12-01

    Many recent studies have shown that organics can alter the water adsorption and cloud condensation nuclei (CCN) activity of common deliquescent species in the Earth's atmosphere. However, very little is known about the effect of organics on water adsorption and CCN activity of common inactive cloud nuclei, such as mineral aerosol. As many studies have shown that a large fraction of unidentified organic material in aerosol particles is composed of polycarboxylic acids resembling humic substances, the presence of these large molecular weight Humic-Like Substances (HULIS) may also alter the water adsorption and CCN activity of mineral aerosol. Thus, we have measured the water adsorption and CCN activity of model humic and fulvic acids. Additionally, the water adsorption and CCN activity of mineral aerosol particles coated with humic and fulvic acids have been studied. We find that humic and fulvic acids show continual multilayer water adsorption as the relative humidity is raised. Additionally, we find that calcite particles mixed with humic and fulvic acids take up more water by mass, by a factor of two, compared to the uncoated calcite particles at approximately 70% RH. CCN measurements also indicate that internally mixed calcite-humic or fulvic acid aerosols are more CCN active than the otherwise inactive, uncoated calcite particles. Our results suggest that mineral aerosol particles coated with high molecular weight organic materials will take up more water and become more efficient CCN in the Earth's atmosphere than single-component mineral aerosol.

  12. Self-Healing Coatings with Multi-Level Protection Based on Active Nanocontainers

    DTIC Science & Technology

    2009-02-01

    of the coating functionalities due to a real healing of the defect retrieving initial coating integrity •R.S. Trask, G.J. Williams, I.P.Bond, J. R...polyelectrolyte nanocontainers for inhibitor encapsulation 0 1 2 3 4 5 70 80 90 100 SiO 2 / PEI SiO 2 a v . p a rt ic le s iz e , n m Layer number...SiO 2 / PEI /PSS SiO 2 / PEI /PSS/BT SiO 2 / PEI /PSS/BT/PSS/BT SiO 2 / PEI /PSS/BT/PSS Layer by Layer assembling process M.L.Zheludkevich, D.G.Shchukin

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

    NASA Technical Reports Server (NTRS)

    Reed, M. W.

    1973-01-01

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

  14. Pack cementation coatings for alloys

    SciTech Connect

    He, Yi-Rong; Zheng, Minhui; Rapp, R.A.

    1996-08-01

    The halide-activated pack cementation process was modified to produce a Ge-doped silicide diffusion coating on a Cr-Cr{sub 2}Nb alloy in a single processing step. The morphology and composition of the coating depended both on the composition of the pack and on the composition and microstructure of the substrate. Higher Ge content in the pack suppressed the formation of CrSi{sub 2} and reduced the growth kinetics of the coating. Ge was not homogeneously distributed in the coatings. In cyclic and isothermal oxidation in air at 700 and 1050{degrees}C, the Ge-doped silicide coating protected the Cr-Nb alloys from significant oxidation by the formation of a Ge-doped silica film. The codeposition and diffusion of aluminum and chromium into low alloy steel have been achieved using elemental Al and Cr powders and a two-step pack cementation process. Sequential process treatments at 925{degrees}C and 1150{degrees}C yield dense and uniform ferrite coatings, whose compositions are close to either Fe{sub 3}Al or else FeAl plus a lower Cr content, when processed under different conditions. The higher content of Al in the coatings was predicted by thermodynamic calculations of equilibrium in the gas phase. The effect of the particle size of the metal powders on the surface composition of the coating has been studied for various combinations of Al and Cr powders.

  15. Constructing a superhydrophobic surface on polydimethylsiloxane via spin coating and vapor-liquid sol-gel process.

    PubMed

    Peng, Yu-Ting; Lo, Kuo-Feng; Juang, Yi-Je

    2010-04-06

    In this study, a superhydrophobic surface on polydimethylsiloxane (PDMS) substrate was constructed via the proposed vapor-liquid sol-gel process in conjunction with spin coating of dodecyltrichlorosilane (DTS). Unlike the conventional sol-gel process where the reaction takes place in the liquid phase, layers of silica (SiO(2)) particles were formed through the reaction between the reactant spin-coated on the PDMS surface and vapor of the acid solution. This led to the SiO(2) particles inlaid on the PDMS surface. Followed by subsequent spin coating of DTS solution, the wrinkle-like structure was formed, and the static contact angle of the water droplet on the surface could reach 162 degrees with 2 degrees sliding angle and less than 5 degrees contact angle hysteresis. The effect of layers of SiO(2) particles, concentrations of DTS solution and surface topography on superhydrophobicity of the surface is discussed.

  16. Process for fabricating high reflectance-low stress Mo--Si multilayer reflective coatings

    DOEpatents

    Montcalm, Claude; Mirkarimi, Paul B.

    2001-01-01

    A high reflectance-low stress Mo--Si multilayer reflective coating particularly useful for the extreme ultraviolet (EUV) wavelength region. While the multilayer reflective coating has particular application for EUV lithography, it has numerous other applications where high reflectance and low stress multilayer coatings are utilized. Multilayer coatings having high near-normal incidence reflectance (R.gtoreq.65%) and low residual stress (.ltoreq.100 MPa) have been produced using thermal and non-thermal approaches. The thermal approach involves heating the multilayer coating to a given temperature for a given time after deposition in order to induce structural changes in the multilayer coating that will have an overall "relaxation" effect without reducing the reflectance significantly.

  17. Preservation of H 2 production activity in nanoporous latex coatings of Rhodopseudomonas palustris CGA009 during dry storage at ambient temperatures: Preservation of R.palustris latex coatings

    SciTech Connect

    Piskorska, M.; Soule, T.; Gosse, J. L.; Milliken, C.; Flickinger, M. C.; Smith, G. W.; Yeager, C. M.

    2013-07-21

    To assess the applicability of latex cell coatings as an ‘off-the-shelf’ biocatalyst, the effect of osmoprotectants, temperature, humidity and O2 on preservation of H2 production in Rhodopseudomonas palustris coatings was evaluated. Immediately following latex coating coalescence (24 h) and for up to 2 weeks of dry storage, rehydrated coatings containing different osmoprotectants displayed similar rates of H2 production. Beyond 2 weeks of storage, sorbitol-treated coatings lost all H2 production activity, whereas considerable H2 production was still detected in sucrose- and trehalose-stabilized coatings. We stored the coatings at a relative humidity level which significantly impacts the recovery and subsequent rates of H2 production. After 4 weeks storage under air at 60% humidity, coatings produced only trace amounts of H2 (0–0.1% headspace accumulation), whereas those stored at < 5% humidity retained 27–53% of their H2 production activity after 8 weeks of storage. Furthermore, when stored in argon at < 5% humidity and room temperature, R. palustris coatings retained full H2 production activity for 3 months, implicating oxidative damage as a key factor limiting coating storage. Ultimately, the results demonstrate that biocatalytic latex coatings are an attractive cell immobilization platform for preservation of bioactivity in the dry state.

  18. Reactive gas pulsing sputtering process, a promising technique to elaborate silicon oxynitride multilayer nanometric antireflective coatings

    NASA Astrophysics Data System (ADS)

    Farhaoui, A.; Bousquet, A.; Smaali, R.; Moreau, A.; Centeno, E.; Cellier, J.; Bernard, C.; Rapegno, R.; Réveret, F.; Tomasella, E.

    2017-01-01

    The oxynitride materials present a high versatility, which enables their properties to be controlled by tuning their elemental composition. This is the case for silicon oxynitrides used for multilayer antireflective coatings (ARCs), where several thin films with various refractive indexes are needed. Different techniques allow for the modification of the thin film composition. In this paper, we investigate the reactive gas pulsing sputtering process to easily tune the thin film composition, from an oxide to a nitride, by controlling the averaged oxygen flow rate, without reducing the deposition rate, compared to a conventional reactive process (CP). We then demonstrated that the refractive indexes of films deposited by this pulsing process (PP) can be varied in the same range compared to films obtained by CP (from 1.83 to 1.45 at 1.95 eV), whereas their extinction coefficients remain low. Finally, the multilayer ARC has been simulated and optimized by a genetic algorithm for wavelength at 600 nm and for the silicon substrate. Various optimized multilayer (mono-, bi- and tri-layers) structures have been deposited by the PP technique and characterized. They are presented in good agreement with the simulated reflectivity. Hence, the PP allows for an easy depositing tri-layer system with a reasonable deposition rate and low reflectivity (8.1% averaged on 400-750 nm visible light range).

  19. 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.

  20. Manipulating Crystallographic Texture of Sn Coatings by Optimization of Electrodeposition Process Conditions to Suppress Growth of Whiskers

    NASA Astrophysics Data System (ADS)

    Jagtap, Piyush; Kumar, Praveen

    2015-04-01

    The effects of two major electrodeposition process conditions, electrolyte bath temperature and current density, on the microstructure and crystallographic texture of pure tin coatings on brass and, ultimately, on the extent of whisker formation have been examined. The grain size of the deposited coatings increased with increasing electrolyte bath temperature and current density, which significantly affected the dominant texture: (211) or (420) was the dominant texture at low current densities whereas, depending on deposition temperature, (200) or (220) became the dominant texture at high current densities. After deposition, coatings were subjected to different environmental conditions, for example isothermal aging (room temperature, 50°C, or 150°C) for up to 90 days and thermal cycling between -25°C and 85°C for 100 cycles, and whisker growth was studied. The Sn coatings with low Miller index planes, for example (200) and (220), and with moderate aging temperature were more prone to whiskering than coating with high Miller index planes, for example (420), and high aging temperature. A processing route involving the optimum combination of current density and deposition temperature is proposed for suppressing whisker growth.

  1. Erosion Performance of Gadolinium Zirconate-Based Thermal Barrier Coatings Processed by Suspension Plasma Spray

    NASA Astrophysics Data System (ADS)

    Mahade, Satyapal; Curry, Nicholas; Björklund, Stefan; Markocsan, Nicolaie; Nylén, Per; Vaßen, Robert

    2017-01-01

    7-8 wt.% Yttria-stabilized zirconia (YSZ) is the standard thermal barrier coating (TBC) material used by the gas turbines industry due to its excellent thermal and thermo-mechanical properties up to 1200 °C. The need for improvement in gas turbine efficiency has led to an increase in the turbine inlet gas temperature. However, above 1200 °C, YSZ has issues such as poor sintering resistance, poor phase stability and susceptibility to calcium magnesium alumino silicates (CMAS) degradation. Gadolinium zirconate (GZ) is considered as one of the promising top coat candidates for TBC applications at high temperatures (>1200 °C) due to its low thermal conductivity, good sintering resistance and CMAS attack resistance. Single-layer 8YSZ, double-layer GZ/YSZ and triple-layer GZdense/GZ/YSZ TBCs were deposited by suspension plasma spray (SPS) process. Microstructural analysis was carried out by scanning electron microscopy (SEM). A columnar microstructure was observed in the single-, double- and triple-layer TBCs. Phase analysis of the as-sprayed TBCs was carried out using XRD (x-ray diffraction) where a tetragonal prime phase of zirconia in the single-layer YSZ TBC and a cubic defect fluorite phase of GZ in the double and triple-layer TBCs was observed. Porosity measurements of the as-sprayed TBCs were made by water intrusion method and image analysis method. The as-sprayed GZ-based multi-layered TBCs were subjected to erosion test at room temperature, and their erosion resistance was compared with single-layer 8YSZ. It was shown that the erosion resistance of 8YSZ single-layer TBC was higher than GZ-based multi-layered TBCs. Among the multi-layered TBCs, triple-layer TBC was slightly better than double layer in terms of erosion resistance. The eroded TBCs were cold-mounted and analyzed by SEM.

  2. Development of coatings for ultrasonic additive manufacturing sonotrode using laser direct metal deposition process

    SciTech Connect

    Sridharan, Niyanth; Dehoff, Ryan R.; Jordan, Brian H.; Babu, Sudarsanam Suresh

    2016-10-01

    ORNL partnered with Fabrisonic, LLC to develop galling resistant hard facing coatings on sonotrodes used to fabricate 3D printed materials using ultrasonic additive manufacturing. The development and deployment of a coated sonotrode is expected to push the existing state of the art to facilitate the solidstate additive manufacturing of hard steels and titanium alloys. To this effect a structurally amorphous stainless steel material and cobalt chrome material were deposited on the sonotrode material. Both the deposits showed good adhesion to the substrate. The coatings made using the structurally amorphous steel materials showed cracking during the initial trials and cracking was eliminated by deposition on a preheated substrate. Both the coatings show hardness in excess of 600 HVN. Thus the phase 1 of this project has been used to identify suitable materials to use to coat the sonotrode. Despite the fact that successful deposits were obtained, the coatings need to be evaluated by performing detailed galling tests at various temperatures. In addition field tests are also necessary to test the stability of these coatings in a high cycle ultrasonic vibration mode. If awarded, phase 2 of the project would be used to optimize the composition of the deposit material to maximize galling resistance. The industrial partner would then use the coated sonotrode to fabricate builds made of austenitic stainless steel to test the viability of using a coated sonotrode.

  3. The deposition of aluminide and silicide coatings on {gamma}-TiAl using the halide-activated pack cementation method

    SciTech Connect

    Munro, T.C; Gleeson, B.

    1996-12-01

    The halide-activated pack cementation method (HAPC) was utilized to deposit aluminide and silicide coatings on nominally stoichiometric {gamma}-TiAl. The deposition temperature was 1,000 C and deposition times ranged from 2 to 12 hours. The growth rates of the coatings were diffusion controlled, with the rate of aluminide growth being about a factor of 2 greater than that of silicide growth. The aluminide coating was inward growing and consisted of a thick, uniform outer layer of TiAl{sub 3} and a thin inner layer of TiAl{sub 2}, with the rate-controlling step being the diffusion of aluminum from the pack into the substrate. Annealing experiments at 1,100 C showed that the interdiffusion between the aluminide coating and the {gamma}-TiAl substrate was rapid. In contrast to the aluminide coating, the silicide coating was nonuniform and porous, consisting primarily of TiSi{sub 2}, TiSi, and Ti{sub 5}Si{sub 4}, with the rate-controlling step for the coating growth believed to be the diffusion of aluminum into the {gamma}-TiAl ahead of the silicide/{gamma}-TiAl interface. The microstructural evolution of the aluminide and silicide coating structures is discussed qualitatively.

  4. Antimicrobial activity of chitosan coatings and films against Listeria monocytogenes on black radish.

    PubMed

    Jovanović, Gordana D; Klaus, Anita S; Nikšić, Miomir P

    2016-01-01

    The antibacterial activity of chitosan coatings prepared with acetic or lactic acid, as well as of composite chitosan-gelatin films prepared with essential oils, was evaluated in fresh shredded black radish samples inoculated with Listeria monocytogenes ATCC 19115 and L. monocytogenes ATCC 19112 during seven days of storage at 4°C. The chitosan coating prepared with acetic acid showed the most effective antibacterial activity. All tested formulations of chitosan films exhibited strong antimicrobial activity on the growth of L. monocytogenes on black radish, although a higher inhibition of pathogens was achieved at higher concentrations of chitosan. The antimicrobial effect of chitosan films was even more pronounced with the addition of essential oils. Chitosan-gelatin films with thyme essential oils showed the most effective antimicrobial activity. A reduction of 2.4log10CFU/g for L. monocytogenes ATCC 19115 and 2.1log10CFU/g for L. monocytogenes ATCC 19112 was achieved in the presence of 1% chitosan film containing 0.2% of thyme essential oil after 24h of storage.

  5. Corrosion-resistant coatings for high-temperature high-sulfur-activity applications. Final report

    SciTech Connect

    Selman, J.R.

    1994-02-01

    The research described in this report is intended to assistant in developing the technology for the production of molybdenum and molybdenum carbide coatings. These coatings have the potential to serve as an alternative to present methods of protecting metal parts at positive potential, of high-temperature sulfur or sulfide batteries. Two methods have been employed. In Task 1, Study of Molybdenum Carbide Electrodeposition from Oxide Based Molten Salts, dense, well-adherent molybdenum carbide coatings have been deposited on mild steel substrates by electrochemical deposition from a Na{sub 2}WO{sub 4}-K{sub 2}WO{sub 4} molten bath containing alkali molybdates and carbonates. Coatings with thicknesses up to 30 {mu}m have been prepared at cathodic current densities between 30 and 50 mA.cm{sup {minus}2} under air as ambient atmosphere. Addition of Na{sub 2}B{sub 4}O{sub 7} to the basic non-lithium bath composition causes significant quality and morphology improvements. It is shown that the initial stages of the molybdenum carbide electrodeposition can be described by a model involving instantaneous nucleation and 3-D diffusion-controlled growth. In Task 2, Preparation of Mo and Mo{sub 2}C by Plasma-Enhanced Chemical Vapor Deposition, using factorial experimental design, a series of experiments has been carried out to investigate the PECVD process with Mo(CO){sub 6} as a precursor. Information about the effects of the chamber pressure, saturator temperature, gas composition and gas flow rate was obtained by experiments. Elemental analysis of the thin film was carried out by Auger electron spectroscopy. Further investigations are being carried out on the basis of thermodynamics, heterogeneous kinetics, and mass transport, in conjunction with measurements of evaporation rate and analysis of the solid and gaseous phases.

  6. Leach-proof magnetic thrombolytic nanoparticles and coatings of enhanced activity.

    PubMed

    Drozdov, Andrey S; Vinogradov, Vasiliy V; Dudanov, Ivan P; Vinogradov, Vladimir V

    2016-06-20

    Despite the fact that magnetic thrombolytic composites is an emerging area, all known so far systems are based on the similar mechanism of action: thrombolytic enzyme releases from the magnetic carrier leaving non-active matrix, thus making the whole system active only for a limited period of time. Such systems often have very complex structure organization and composition, consisting of materials not approved for parenteral injection, making them poor candidates for real clinical trials and implementation. Here we report, for the first time, the production of thrombolytic magnetic composite material with non-releasing behavior and prolonged action. Obtained composite shows good thrombolytic activity, consists of fully biocompatible materials and could be applied as infinitely active thrombolytic coatings or magnetically-targetable thrombolytic agents.

  7. Leach-proof magnetic thrombolytic nanoparticles and coatings of enhanced activity

    PubMed Central

    Drozdov, Andrey S.; Vinogradov, Vasiliy V.; Dudanov, Ivan P.; Vinogradov, Vladimir V.

    2016-01-01

    Despite the fact that magnetic thrombolytic composites is an emerging area, all known so far systems are based on the similar mechanism of action: thrombolytic enzyme releases from the magnetic carrier leaving non-active matrix, thus making the whole system active only for a limited period of time. Such systems often have very complex structure organization and composition, consisting of materials not approved for parenteral injection, making them poor candidates for real clinical trials and implementation. Here we report, for the first time, the production of thrombolytic magnetic composite material with non-releasing behavior and prolonged action. Obtained composite shows good thrombolytic activity, consists of fully biocompatible materials and could be applied as infinitely active thrombolytic coatings or magnetically-targetable thrombolytic agents. PMID:27321930

  8. Leach-proof magnetic thrombolytic nanoparticles and coatings of enhanced activity

    NASA Astrophysics Data System (ADS)

    Drozdov, Andrey S.; Vinogradov, Vasiliy V.; Dudanov, Ivan P.; Vinogradov, Vladimir V.

    2016-06-01

    Despite the fact that magnetic thrombolytic composites is an emerging area, all known so far systems are based on the similar mechanism of action: thrombolytic enzyme releases from the magnetic carrier leaving non-active matrix, thus making the whole system active only for a limited period of time. Such systems often have very complex structure organization and composition, consisting of materials not approved for parenteral injection, making them poor candidates for real clinical trials and implementation. Here we report, for the first time, the production of thrombolytic magnetic composite material with non-releasing behavior and prolonged action. Obtained composite shows good thrombolytic activity, consists of fully biocompatible materials and could be applied as infinitely active thrombolytic coatings or magnetically-targetable thrombolytic agents.

  9. Numerical investigation of solid mixing in a fluidized bed coating process

    NASA Astrophysics Data System (ADS)

    Kenche, Venkatakrishna; Feng, Yuqing; Ying, Danyang; Solnordal, Chris; Lim, Seng; Witt, Peter J.

    2013-06-01

    Fluidized beds are widely used in many process industries including the food and pharmaceutical sectors. Despite being an intensive research area, there are no design rules or correlations that can be used to quantitatively predict the solid mixing in a specific system for a given set of operating conditions. This paper presents a numerical study of the gas and solid dynamics in a laboratory scale fluidized bed coating process used for food and pharmaceutical industries. An Eulerian-Eulerian model (EEM) with kinetic theory of granular flow is selected as the modeling technique, with the commercial computational fluid dynamics (CFD) software package ANSYS/Fluent being the numerical platform. The flow structure is investigated in terms of the spatial distribution of gas and solid flow. The solid mixing has been evaluated under different operating conditions. It was found that the solid mixing rate in the horizontal direction is similar to that in the vertical direction under the current design and operating conditions. It takes about 5 s to achieve good mixing.

  10. Planarization coating for polyimide substrates used in roll-to-roll fabrication of active matrix backplanes for flexible displays

    NASA Astrophysics Data System (ADS)

    Almanza-Workman, A. Marcia; Jeans, Albert; Braymen, Steve; Elder, Richard E.; Garcia, Robert A.; de la Fuente Vornbrock, Alejandro; Hauschildt, Jason; Holland, Edward; Jackson, Warren; Jam, Mehrban; Jeffrey, Frank; Junge, Kelly; Kim, Han-Jun; Kwon, Ohseung; Larson, Don; Luo, Hao; Maltabes, John; Mei, Ping; Perlov, Craig; Smith, Mark; Stieler, Dan; Taussig, Carl P.; Trovinger, Steve; Zhao, Lihua

    2012-03-01

    Good surface quality of plastic substrates is essential to reduce pixel defects during roll-to-roll fabrication of flexible display active matrix backplanes. Standard polyimide substrates have a high density of "bumps" from fillers and belt marks and other defects from dust and surface scratching. Some of these defects could be the source of shunts in dielectrics. The gate dielectric must prevent shorts between the source/drain and the gate in the transistors, resist shorts in the hold capacitor and stop shorts in the data/gate line crossovers in active matrix backplanes fabricated by self-aligned imprint lithography (SAIL) roll-to-roll processes. Otherwise data and gate lines will become shorted creating line or pixel defects. In this paper, we discuss the development of a proprietary UV curable planarization material that can be coated by roll-to-roll processes. This material was engineered to have low shrinkage, excellent adhesion to polyimide, high dry etch resistance, and great chemical and thermal stability. Results from PECVD deposition of an amorphous silicon stack on the planarized polyimide and compatibility with roll-to-roll processes to fabricate active matrix backplanes are also discussed. The effect of the planarization on defects in the stack, shunts in the dielectric and curvature of finished arrays will also be described.

  11. A facile process for preparing superhydrophobic PBZ-PTFE coating with excellent stable properties

    NASA Astrophysics Data System (ADS)

    Lei, Sheng; Shi, Zhongqi; Ou, Junfei; Li, Wen; Qiao, Guanjun; Yu, Xinhua

    2016-12-01

    We present a facile way to fabricate superhydrophobic PBZ-PTFE coating which can be easily prepared in large scale. The superhydrophobic PBZ-PTFE coating was prepared by spraying the PTFE condensed dispersion solution and the benzoxazine mixture solution on the substrate. The water contact angle on the prepared coating reaches 166.5°, and the sliding angle is only 1°. The PTFE weight fraction is optimized to 60% which provides high surface roughness of 3.54 μm required for superhydrophobicity. Importantly, the superhydrophobic coating exhibits excellent temperature stability and corrosion resistance. In addition, the stability of the superhydrophobic coating was evaluated by adhesive tape peeling experiment, bend test, crosscut test and water impact test. We expect that this fabrication technique will have great prospects for industrial applications.

  12. Application of Pcvd Process to Uniform Coating of TiO2 Thin Films on Polypropylene Beads

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Joo; Pham, Hung Cuong; Kim, Kyo-Seon

    The growth of the TiO2 thin films coated on the polypropylene beads was analyzed experimentally in a rotating cylindrical plasma chemical vapor deposition (PCVD) reactor. The precursors for the thin films were generated by plasma reactions, and they deposited on the polypropylene beads to become the uniform thin films. The TiO2 thin films grow more quickly on the polypropylene beads by increasing the mass flow rate of TTIP, or the rotation speed of the reactor. The smaller number of polypropylene beads in the reactor increases the growth rate of the thin films. The high-quality TiO2 thin films can be coated on particles uniformly by using the rotating cylindrical PCVD process. The particles coated with high-quality TiO2 thin films can be applied to the removal of air and water pollutants by a photodegradation reaction of TiO2.

  13. Controlled Growth of Ultrathin Film of Organic Semiconductors by Balancing the Competitive Processes in Dip-Coating for Organic Transistors.

    PubMed

    Wu, Kunjie; Li, Hongwei; Li, Liqiang; Zhang, Suna; Chen, Xiaosong; Xu, Zeyang; Zhang, Xi; Hu, Wenping; Chi, Lifeng; Gao, Xike; Meng, Yancheng

    2016-06-28

    Ultrathin film with thickness below 15 nm of organic semiconductors provides excellent platform for some fundamental research and practical applications in the field of organic electronics. However, it is quite challenging to develop a general principle for the growth of uniform and continuous ultrathin film over large area. Dip-coating is a useful technique to prepare diverse structures of organic semiconductors, but the assembly of organic semiconductors in dip-coating is quite complicated, and there are no reports about the core rules for the growth of ultrathin film via dip-coating until now. In this work, we develop a general strategy for the growth of ultrathin film of organic semiconductor via dip-coating, which provides a relatively facile model to analyze the growth behavior. The balance between the three direct factors (nucleation rate, assembly rate, and recession rate) is the key to determine the growth of ultrathin film. Under the direction of this rule, ultrathin films of four organic semiconductors are obtained. The field-effect transistors constructed on the ultrathin film show good field-effect property. This work provides a general principle and systematic guideline to prepare ultrathin film of organic semiconductors via dip-coating, which would be highly meaningful for organic electronics as well as for the assembly of other materials via solution processes.

  14. Formation process of in situ oxide coatings with high porosity using one-step plasma electrolytic oxidation

    NASA Astrophysics Data System (ADS)

    Yu, Xiwen; Chen, Li; Qin, Honglei; Wu, Mingyue; Yan, Zongcheng

    2016-03-01

    Porous oxide films prepared via plasma electrolytic oxidation are ideal in situ catalysts. However, such films have low porosity. To overcome this limitation, we proposed a promising approach that controls discharge events. The treatments were performed in two kinds of alkaline-silicate solutions namely KOH-enriched solution and Na2SiO3-enriched solution. The coatings prepared in the former electrolyte exhibited superior growth behaviors and catalytic structures. Due to the strong corrosive of KOH-enriched electrolyte, the growth of the film was suppressed, and the sparks were maintained small and evenly distributed throughout the process. Such layers showed high porosity and were evenly covered by nanoparticles. The coating porosity increased with increasing time, and the film treated for 60 min exhibited a high porosity of 33.3 ± 1.7%. Moreover, an oxide film with an outer dendritic and inner porous structure was formed within 120 min. The energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy characterizations indicated that the coatings were mainly composed of aluminum oxide and that the doped iron oxide was enriched on the top surface of the coating. Finally, the formation mechanisms of the coating and nanoparticles were discussed with consideration of the dynamic equilibrium theory.

  15. Water adsorption and cloud condensation nuclei activity of calcite and calcite coated with model humic and fulvic acids

    NASA Astrophysics Data System (ADS)

    Hatch, Courtney D.; Gierlus, Kelly M.; Schuttlefield, Jennifer D.; Grassian, Vicki H.

    Recent studies have shown that organics can alter the water adsorption and cloud condensation nuclei (CCN) activity of common deliquescent species in the Earth's atmosphere. However, very little is known about the effect of organics on water adsorption and CCN activity of insoluble nuclei, such as mineral dust aerosol. A large fraction of unidentified organic material in aerosol particles is composed of poly-acidic compounds resembling humic substances. The presence of these humic-like substances (HULIS) can alter the water adsorption and CCN activity of mineral dust aerosol. We have measured the CCN activity of model humic and fulvic acids and of mineral dust particles coated with these substances in the laboratory. We find that coatings of humic and fulvic acids on calcite particles significantly increases water adsorption compared to uncoated particles. CCN measurements indicate that humic- or fulvic acid-coated calcite particles are more CCN active than uncoated calcite particles. Additionally, thicker coatings of humic or fulvic acids appear to result in more efficient CCN activity. Thus, mineral dust particles coated with high molecular weight organic materials will take up more water and become more efficient CCN in the atmosphere than uncoated mineral dust particles, potentially altering the effect of mineral dust on the Earth's climate. In addition to the experimental results, we have explored a newly modified Köhler theory for predicting the CCN activity of insoluble, wettable particles based on multi layer water adsorption measurements of calcite.

  16. Efficacy of coating activated carbon with milk proteins to prevent binding of bacterial cells from foods for PCR detection.

    PubMed

    Opet, Nathan J; Levin, Robert E

    2013-08-01

    Foods contaminated with pathogens are common sources of illness. Currently, the most common and sensitive rapid detection method involves the PCR. However, food matrices are complex and contain inhibitors that limit the sensitivity of the PCR. The use of coated activated carbon can effectively facilitate the removal of PCR inhibitors without binding targeted bacterial cells from food samples. With the use of activated carbon coated with milk proteins, a cell recovery at pH 7.0 of 95.7%±2.0% was obtained, compared to control uncoated activated carbon, which yielded a cell recovery of only 1.1%±0.8%. In addition, the milk protein coated activated carbon was able to absorb similar amounts of soluble compounds as uncoated activated carbon, with the exception of bovine hemoglobin. This suggests that the use of milk proteins to coat activated carbon may therefore serve as a suitable replacement for bentonite in the coating of activated carbon, which has previously been used for the removal of PCR inhibitors from food.

  17. Structural evolution, thermomechanical recrystallization and electrochemical corrosion properties of Ni-Cu-Mg amorphous coating on mild steel fabricated by dual-anode electrolytic processing

    NASA Astrophysics Data System (ADS)

    Abdulwahab, M.; Fayomi, O. S. I.; Popoola, A. P. I.

    2016-07-01

    The electrolytic Ni-Cu based alloy coating with admixed interfacial blend of Mg have been successfully prepared on mild steel substrate by dual anode electroplating processes over a range of applied current density and dwell time. The electrocodeposition of Ni-Cu-Mg coating was investigated in the presence of other bath additives. The influence of deposition current on surface morphology, adhesion behavior, preferred crystal orientation, surface topography and electrochemical activity of Ni-Cu-Mg alloy coating on mild steel were systematically examined. The thermal stability of the developed composite materials was examined via isothermal treatment. Scanning electron microscope equipped with EDS, X-ray diffraction, Atomic force microscope, micro-hardness tester and 3 μmetrohm Potentiostat/galvanostat were used to compare untreated and isothermally treated electrocodeposited composite. The induced activity of the Ni-Cu-Mg alloy changed the surface modification and results to crystal precipitation within the structural interface by the formation of Cu, Ni2Mg3 phase. The obtained results showed that the introduction of Mg particles in the plating bath generally modified the surface and brings an increase in the hardness and corrosion resistance of Ni-Cu-Mg layers fabricated. Equally, isothermally treated composites demonstrated an improved properties indicating 45% increase in the micro-hardness and 79.6% corrosion resistance which further showed that the developed composite is thermally stable.

  18. Some preliminary evaluations of black coating on aluminium AA2219 alloy produced by plasma electrolytic oxidation (PEO) process for space applications

    NASA Astrophysics Data System (ADS)

    Shrestha, S.; Merstallinger, A.; Sickert, D.; Dunn, B. D.

    2003-09-01

    This paper describes the results of a study of a black coating produced on aluminium AA2219 alloy using a process that involves creation of a hard ceramic oxide layer on the surface of the alloy by plasma electrolytic oxidation (PEO) known as the 'KERONITE®' process. Coating microstructure has been examined and the coating characteristics such as porosity, hardness, adhesion and phase composition were measured. The thermo-optical properties such as solar absorptance 'as' and normal infrared emittance 'en-IR' of the coating were measured in the 'as-prepared' condition and after environmental exposures to humidity, thermal cycling and UV-radiation in vacuum and to thermal shock. Comparison was made with alternative coatings produced using standard black anodising processes. The study also looked at the cold welding and friction behaviours of the coated alloy in vacuum and in an ambient laboratory environment. Standard spacecraft materials tests were conducted on the coated disc against an AISI 52100 steel ball and also against a coated pin using a pin-on-disc apparatus. Parameters such as friction coefficient and wear depth were measured and the cold welding behaviours were investigated. Test results were compared with the data generated for NiCr plated and anodised coatings. Corrosion performance was assessed using a salt spray exposure test and using an accelerated electrochemical test method. In addition, the study looked at the effect of post coating sealing with a sol-gel solution.

  19. Biocompatibility and anti-microbiological activity characterization of novel coatings for dental implants: A primer for non-biologists

    NASA Astrophysics Data System (ADS)

    Monsees, Thomas

    2016-08-01

    With regard to biocompatibility, the cardinal requirement for dental implants and other medical devices that are in long-term contact with tissue is that the material does not cause any adverse effect to the patient. To warrant stability and function of the implant, proper osseointegration is a further prerequisite. Cells interact with the implant surface as the interface between bulk material and biological tissue. Whereas structuring, deposition of a thin film or other modifications of the surface are crucial parameters in determining favorable adhesion of cells, corrosion of metal surfaces and release of ions can affect cell viability. Both parameters are usually tested using in vitro cytotoxicity and adhesion assays with bone or fibroblasts cells. For bioactive surface modifications, further tests should be considered for biocompatibility evaluation. Depending on the type of modification, this may include analysis of specific cell functions or the determination of antimicrobial activities. The latter is of special importance as bacteria and yeast present in the oral cavity can be introduced during the implantation process and this may lead to chronic infections and implant failure. An antimicrobial coating of the implant is a way to avoid that. This review describes the essential biocompatibility assays for evaluation of new implant materials required by ISO 10993 and also gives an overview on recent test methods for specific coatings of dental implants.

  20. Active control of the optical properties of nanoscale coatings using 'smart' nanoparticles

    NASA Astrophysics Data System (ADS)

    Cortie, Michael B.; Barnett, Michael; Ford, Michael J.

    2007-09-01

    Coatings that can self-modulate their optical properties as a function of an external stimulus are of significant technological interest. In this regard, the possibilities for thermo- or electrochromic materials such as VO II and WO 3 are already comparatively well-known. Here, however, we explore a new kind of 'smart' coating, based on the active control of a plasmon resonance in nanoparticles. One possible system is based on the modulation of the plasmon resonance of a precious metal nanorod or nanosphere by an active dielectric shell. The active dielectric undergoes an insulator-to-metal transition on increase of temperature which modulates the plasmon resonance of the underlying precious metal nanoparticle, thereby changing the wavelength at which its optical extinction is maximum. In the case of nanorods, the absorption maximum of the longitudinal plasmon is particularly sensitive to the aspect ratio of the nanoparticle and the dielectric properties of the environment, and may be readily tuned across the visible and near-infrared portions of the spectrum. In addition, nanoparticles of certain thermochromic dielectrics, such as VO II, are expected to have a plasmon resonance of their own which can be switched on or off by control of the temperature. We consider some of the possibilities, using both the discrete dipole approximation and the exact analytical solution due to Mie to calculate the optical properties.

  1. Processing of Color Words Activates Color Representations

    ERIC Educational Resources Information Center

    Richter, Tobias; Zwaan, Rolf A.

    2009-01-01

    Two experiments were conducted to investigate whether color representations are routinely activated when color words are processed. Congruency effects of colors and color words were observed in both directions. Lexical decisions on color words were faster when preceding colors matched the color named by the word. Color-discrimination responses…

  2. Low Friction Property of Diamond-Like Carbon Coating Films and Oxygen Transmission Ratio of Amorphous Carbon Films Deposited by Advanced Coating Processes

    NASA Astrophysics Data System (ADS)

    Watanabe, Toshiyuki; Kano, Makoto; Yoshida, Kentaro; Suzuki, Tetsuya

    2012-09-01

    The topics of the applied technology of amorphous carbon film to reduce friction using diamond-like carbon (DLC) coated by the vacuum arc ion plating process and to improve the gas barrier property using the amorphous carbon film by the atmospheric pressure plasma process are introduced with the basic experimental results. For reducing friction, the super low friction coefficient below 0.01 has been found when the tetrahedral amorphous carbon coating deposited by T-shape filtered arc deposition method [ta-C(T)] was evaluated the friction property under oleic acid lubrication at pure sliding condition. It was thought that the low share strength tribofilm composed of water and oleic acid mono-layer seemed to be formed on the sliding interface. For gas barrier performance, the amorphous carbon film deposited by the atmospheric pressure plasma chemical vapour deposition (CVD) technique on poly(ethylene terephthalate) (PET) substrate was improved the oxygen transmission ratio (OTR) around 30% compared with that of uncoated PET substrate. These advanced performance obtained by the optimum material combination of DLC with lubricant and the original atmospheric pressure plasma CVD technique are expected to be applied on the actual application for the different types of the industrial fields in near future.

  3. Biological influence of Ca/P ratio on calcium phosphate coatings by sol-gel processing.

    PubMed

    Catauro, M; Papale, F; Sapio, L; Naviglio, S

    2016-08-01

    The objective of this work has been to develop low temperature sol-gel glass coatings to modify the substrate surface and to evaluate their bioactivity and biocompatibility. Glasses, based on SiO2·CaO·P2O5, were synthesized by the sol-gel technique using tetraethyl orthosilicate, calcium nitrate tetrahydrate and triethyl phosphate as precursors of SiO2, CaO and P2O5, respectively. Those materials, still in the sol phase, have been used to coat substrates by means of the dip-coating technique. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) has been used for characterize coatings and a microstructural analysis has been obtained using scanning electron microscopy (SEM). The potential applications of the coatings in the biomedical field were evaluated by bioactivity and biocompatibility tests. The coated substrate was immersed in simulated body fluid (SBF) for 21days and the hydroxyapatite deposition on its surface was subsequently evaluated via SEM-EDXS analysis, as an index of bone-bonding capability. In order to study the cell behavior and response to our silica based materials, prepared via the sol-gel method, with various Ca/P ratio and coating substrate, we have used the human osteoblast-like U2OS cell line.

  4. Can deformation of a polymer film with a rigid coating model geophysical processes?

    PubMed

    Volynskii, A L; Bazhenov, S L

    2007-12-01

    The structural and mechanical behavior of polymer films with a thin rigid coating is analyzed. The behavior of such systems under applied stress is accompanied by the formation of a regular wavy surface relief and by regular fragmentation of the coating. The above phenomena are shown to be universal. Both phenomena (stress-induced development of a regular wavy surface relief and regular fragmentation of the coating) are provided by the specific features of mechanical stress transfer from a compliant soft support to a rigid thin coating. The above phenomena are associated with a specific structure of the system, which is referred to as "a rigid coating on a soft substratum" system (RCSS). Surface microrelief in RCSS systems is similar to the ocean floor relief in the vicinity of mid-oceanic ridges. Thus, the complex system composed of a young oceanic crust and upper Earth's mantle may be considered as typically "a solid coating on a soft substratum" system. Specific features of the ocean floor relief are analyzed in terms of the approach advanced for the description of the structural mechanical behavior of polymer films with a rigid coating. This analysis allowed to estimate the strength of an ocean floor.

  5. Bioactive glass coatings with hydroxyapatite and Bioglass (registered) particles on Ti-based implants. 1. Processing

    SciTech Connect

    Gomez-Vega, J.M.; Saiz, E.; Tomsia, A.P.; Marshall, G.W.; Marshall, S.J.

    1999-06-01

    Silicate-based glasses with thermal expansion coefficients that match those of Ti6Al4V were prepared and used to coat Ti6Al4V by a simple enameling technique. Bioglass (BG) (registered) or hydroxyapatite (HA) particles were embedded on the coatings in order to enhance their bioactivity. HA particles were partially embedded during heating and remained firmly embedded on the coating after cooling. There was no apparent reaction at the glass/HA interface at the temperatures used in this work (800-840 degrees C). In contrast, BG particles softened and some infiltration into the glass coating took place during heat treatment. In this case, particles with sizes over 45 (mu)m were required, otherwise the particles became hollow due to the infiltration and crystallization of the glass surface. The concentration of the particles on the coating was limited to 20% of surface coverage. Concentrations above this value resulted in cracked coatings due to excessive induced stress. Cracks did not prop agate along the interfaces when coatings were subjected to Vickers indentation tests, indicating that the particle/glass and glass/metal interfaces exhibited strong bonds. Enameling, producing excellent glass/metal adhesion with well-attached bioactive particles on the surface, is a promising method of forming reliable and lasting implants which can endure substantial chemical and mechanical stresses.

  6. Processing - microstructure relationships of chemically vapor deposited zirconia fiber coating for environmentally durable silicon carbide/silicon carbide composites

    NASA Astrophysics Data System (ADS)

    Lee, Jinil

    In SiC/SiC ceramic matrix composites, toughness is obtained by adding a fiber coating which provides a weak interface for crack deflection and debonding between the fiber and the matrix. However, the most commonly used fiber coatings, carbon and boron nitride, are unstable in oxidative environments. In the present study, the feasibility of using a chemically vapor deposited zirconia (CVD-ZrO 2) fiber coating as an oxidation-resistant interphase for SiC/SiC composites was investigated. The feasibility of the CVD-ZrO2 coating as a useful interphase for SiC/SiC composites was investigated with emphasis on developing critical processing-microstructure relationships. A study of morphological evolution in the CVD-ZrO2 coating suggested that a size-controlled displacive phase transformation from tetragonal ZrO2 (t-ZrO2) to monoclinic ZrO2 (m-ZrO2) was the key mechanism responsible for the weak interface behavior exhibited by the ZrO2 coating. The pre-delamination occurred as a result of (i) continuous formation of t-ZrO2 nuclei on the deposition surface; (ii) martensitic transformation of the tetragonal phase to a monoclinic phase upon reaching a critical grain size; and (iii) development of significant compressive hoop stresses due to the volume dilation associated with the transformation. We also discovered that low oxygen partial pressure in the CVD reactor was required for the nucleation of t-ZrO2 and was ultimately responsible for the delamination behavior. The effects of oxygen partial pressure on the nucleation behavior of the CVD-ZrO2 coating was systematically studied by intentionally adding the controlled amount of O2 into the CVD chamber. Characterization results suggested that the number density of t-ZrO2 nuclei apparently decreased with increasing the oxygen partial pressure from 0.004 to 1.6 Pa. Also, the coating layer became more columnar and contained larger m-ZrO2 grains. The observed relationships between the oxygen partial pressure and the morphological

  7. UV-activated 7-dehydrocholesterol-coated titanium implants promote differentiation of human umbilical cord mesenchymal stem cells into osteoblasts.

    PubMed

    Satué, María; Ramis, Joana M; Monjo, Marta

    2016-01-01

    Vitamin D metabolites are essential for bone regeneration and mineral homeostasis. The vitamin D precursor 7-dehydrocholesterol can be used after UV irradiation to locally produce active vitamin D by osteoblastic cells. Furthermore, UV-irradiated 7-dehydrocholesterol is a biocompatible coating for titanium implants with positive effects on osteoblast differentiation. In this study, we examined the impact of titanium implants surfaces coated with UV-irradiated 7-dehydrocholesterol on the osteogenic differentiation of human umbilical cord mesenchymal stem cells. First, the synthesis of cholecalciferol (D3) was achieved through the incubation of the UV-activated 7-dehydrocholesterol coating for 48 h at 23℃. Further, we investigated in vitro the biocompatibility of this coating in human umbilical cord mesenchymal stem cells and its potential to enhance their differentiation towards the osteogenic lineage. Human umbilical cord mesenchymal stem cells cultured onto UV-irradiated 7-dehydrocholesterol-coated titanium implants surfaces, combined with osteogenic supplements, upregulated the gene expression of several osteogenic markers and showed higher alkaline phosphatase activity and calcein blue staining, suggesting increased mineralization. Thus, our results show that the use of UV irradiation on 7-dehydrocholesterol -treated titanium implants surfaces generates a bioactive coating that promotes the osteogenic differentiation of human umbilical cord mesenchymal stem cells, with regenerative potential for improving osseointegration in titanium-based bone anchored implants.

  8. Development and evaluation of Mn oxide-coated composite adsorbent for the removal and recovery of heavy metals from coal processing wastewater. Final report, December 1995

    SciTech Connect

    Fan, Huan Jung; Anderson, P.R.

    1995-12-31

    The overall objective of this research was to evaluate a Mn oxide-coated granular activated carbon (MnGAC) for the removal and recovery of metals from wastewaters. The composite adsorbent was prepared by coating M-n-oxide onto granular activated carbon. Three coating methods (adsorption, precipitation, and dry oxidation) were developed and studied in this research. The adsorbent (MnTOG) prepared by a dry oxidation method had the highest Cu(II) adsorption capacity of the three synthesis methods. In multiple adsorption/regeneration cycle tests, MnTOG had better Cu(II) removal relative to those adsorbents prepared by other methods. MnTOG had the ability to remove Cu(II) and Cd(II) to trace level (< 4 ug/L) in a column process at least through 3000 and 1400 BV, respectively. Cd(II) removal was hindered by the presence of Cu(II). However, Cu(II) removal was only slightly reduced by the presence of Cd(II). Cu(II) adsorption in batch and fixed-bed processes onto MnTOG was successfully modeled with a homogeneous surface diffusion model (HSDM). However, the HSDM could only successfully describe the adsorption of Cd(II) onto MnTOG in the batch process, but not the fixed-bed process. M-n oxide can be deposited on GAC to create a composite adsorbent with an increased Cu(II) or Cd(II) adsorption capacity. Composite adsorbent (MnGAC) has the potential to become an efficient way to remove metals from metal contaminated wastewater.

  9. Conducting polymers on non-conducting substrates: Chemical coating processes and applications

    NASA Astrophysics Data System (ADS)

    Geniès, Eugène M.

    1996-01-01

    The presentation will be as follows: —Historical background —Oxidizing polymerization mechanism of heterocycles and aromatic compounds: the cases of pyrrole and anilin —The processes: solute, gas phase and from conducting polymer solutions —The substrates: glass, polymers, inorganic materials, textiles, powders. —Properties of coatings: —Chemical properties: redox, acid-base —Properties resulting from the polymer doping counter-ion —Physical properties: : optical, magnetic, conducting, microwave absorption —Stability —Applications: optics, microelectronics, sensors, electrochrome glasses, electromagnetic and antistatic shielding, military applications, packaging for electronic components, biocompat- ibility, plasturgy. —Commercial applications throughout the world. How to obtain these materials —Conclusions The examples will be taken from the results of our laboratory, those of CEA-Direction des Technologies Avancées—Centre d'Etudes et de Recherche sur les Matériaux—Centre d'Etudes Nucléaires de Grenoble (Mssrs R. Jolly and J. C. Thiéblemont), from the Milliken Research Corp. (Dr. H. H. Kuhn), from the Zipperlin Kessler company (Dr. B. Wessling), from the Americhem company and from I.B.M. (Dr. M. Angelopoulos).

  10. Speech perception as an active cognitive process.

    PubMed

    Heald, Shannon L M; Nusbaum, Howard C

    2014-01-01

    One view of speech perception is that acoustic signals are transformed into representations for pattern matching to determine linguistic structure. This process can be taken as a statistical pattern-matching problem, assuming realtively stable linguistic categories are characterized by neural representations related to auditory properties of speech that can be compared to speech input. This kind of pattern matching can be termed a passive process which implies rigidity of processing with few demands on cognitive processing. An alternative view is that speech recognition, even in early stages, is an active process in which speech analysis is attentionally guided. Note that this does not mean consciously guided but that information-contingent changes in early auditory encoding can occur as a function of context and experience. Active processing assumes that attention, plasticity, and listening goals are important in considering how listeners cope with adverse circumstances that impair hearing by masking noise in the environment or hearing loss. Although theories of speech perception have begun to incorporate some active processing, they seldom treat early speech encoding as plastic and attentionally guided. Recent research has suggested that speech perception is the product of both feedforward and feedback interactions between a number of brain regions that include descending projections perhaps as far downstream as the cochlea. It is important to understand how the ambiguity of the speech signal and constraints of context dynamically determine cognitive resources recruited during perception including focused attention, learning, and working memory. Theories of speech perception need to go beyond the current corticocentric approach in order to account for the intrinsic dynamics of the auditory encoding of speech. In doing so, this may provide new insights into ways in which hearing disorders and loss may be treated either through augementation or therapy.

  11. Fabrication of nano-structured calcium silicate coatings with enhanced stability, bioactivity and osteogenic and angiogenic activity.

    PubMed

    Wang, Xiuhui; Zhou, Yuning; Xia, Lunguo; Zhao, Cancan; Chen, Lei; Yi, Deliang; Chang, Jiang; Huang, Liping; Zheng, Xuebin; Zhu, Huiying; Xie, Youtao; Xu, Yuanjin; Lin, Kaili

    2015-02-01

    The bioactivity and stability of coatings on alloy implants play critical roles in the fast osseointegration and maintenance of a long-term life span of the implants, respectively. Herein, nano-sheet surface on bioactive calcium silicate (CaSiO3, CS) coatings on metal substrates was fabricated by combining atmosphere plasma spraying (APS) and hydrothermal technology (HT). The glassy phase in CS coatings generated by APS was converted into crystalline sheet-like nano-structures after HT treatment. Compared with the original CS coating samples, HT treatment decreased the degradation rate of the CS coatings. Moreover, the fabricated nano-structured topography of CS coatings increased the apatite mineralization ability and significantly enhanced the cell attachment, proliferation, differentiation, alkaline phosphatase (ALP) activity and expression of osteogenic genes and angiogenic factors of rat bone marrow stromal cells (bMSCs). Our results suggest that the nano-structured CS coatings have immense potential in improving the clinical performance of medical implants.

  12. Metallization Process of a Polyimide Surface with Palladium-Free Activation for Electronic Field Applications

    NASA Astrophysics Data System (ADS)

    Li, Libo; Ma, Yue; Xie, Jingchen; Yang, Xiuchun; Wang, Heng; Tian, Haiyan; Mu, Hongjing; Wang, Wentao

    2015-10-01

    A new copper plating bath without Pd activation for electroless deposition on polyimide (PI) film is reported. The characteristics of Cu coatings on the PI via electroless plating and the effects of operating parameters on the coating coverage are discussed. The pre-treatment and plating processes are further optimized based on orthogonal experiment methods, involving variations of multiple process parameters. The electroless copper coating was characterized by scanning electron microscopy and atomic force microscopy, while the composition and crystalline structure are estimated by energy dispersive spectrometer and x-ray diffraction, respectively. These results show that the crystalline copper layer on the PI surface after electroless plating is dense, continuous and uniform. The joint tensile experiment is used to measure the adhesive strength of the coating with palladium-free and palladium activation, and the former is higher. Furthermore, the pre-treatment method proposed in this work without using palladium compounds is considered to be environmentally friendly. In addition, it provides a new concept of electroless Cu plating on the PI, which is generally difficult to plate due to its hydrophobic nature.

  13. Combustion chemical vapor desposited coatings for thermal barrier coating systems

    SciTech Connect

    Hampikian, J.M.; Carter, W.B.

    1995-10-01

    The new deposition process, combustion chemical vapor deposition, shows a great deal of promise in the area of thermal barrier coating systems. This technique produces dense, adherent coatings, and does not require a reaction chamber. Coatings can therefore be applied in the open atmosphere. The process is potentially suitable for producing high quality CVD coatings for use as interlayers between the bond coat and thermal barrier coating, and/or as overlayers, on top of thermal barrier coatings.

  14. 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.

  15. 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.

  16. Microstructure and Properties of Cu Coating Fabricated onto Diamond-Cu Substrate by Low-Temperature HVOF Process

    NASA Astrophysics Data System (ADS)

    Liu, Min; Yang, Kun; Deng, Chun-ming; Deng, Chang-guang; Zhou, Ke-song

    2016-12-01

    Diamond-Cu composites have been considered to be the next generation of electronic packing materials. One of the key stumbles for such an application is the joining problem between diamond-Cu composites and other materials due to the poor wettability of the diamond particles in the composites. In order to overcome this hurdle, pure Cu powder was thermally sprayed onto diamond-Cu substrate by low-temperature high-velocity oxygen fuel spraying process. Microstructure and some fundamental properties of the coating obtained were systematically investigated, and morphologies of the single splat deposited on the diamond-Cu substrate were also observed. The splats obtained have good adhesion with the substrate as fine particles flattened sufficiently, while the coarse particles were significantly deformed. The coating was quite dense with porosity lower than 1%, oxygen content under 0.5% and thermal conductivity about 266 Wm-1 K-1 and still remained on the diamond-Cu substrate after 50 thermal shock cycles between 300 °C and water bath at room temperature. Meanwhile, the solderability of the coating was significantly improved. Therefore, Cu coating deposited on diamond-Cu substrate by low-temperature high-velocity oxygen fuel spraying process can be beneficial in electronic industry assisting with soldering and improved wettability for joining of other materials.

  17. Controlling contagion processes in activity driven networks.

    PubMed

    Liu, Suyu; Perra, Nicola; Karsai, Márton; Vespignani, Alessandro

    2014-03-21

    The vast majority of strategies aimed at controlling contagion processes on networks consider the connectivity pattern of the system either quenched or annealed. However, in the real world, many networks are highly dynamical and evolve, in time, concurrently with the contagion process. Here, we derive an analytical framework for the study of control strategies specifically devised for a class of time-varying networks, namely activity-driven networks. We develop a block variable mean-field approach that allows the derivation of the equations describing the coevolution of the contagion process and the network dynamic. We derive the critical immunization threshold and assess the effectiveness of three different control strategies. Finally, we validate the theoretical picture by simulating numerically the spreading process and control strategies in both synthetic networks and a large-scale, real-world, mobile telephone call data set.

  18. Mesoporous silica coatings for cephalosporin active release at the bone-implant interface

    NASA Astrophysics Data System (ADS)

    Rădulescu, Dragoş; Voicu, Georgeta; Oprea, Alexandra Elena; Andronescu, Ecaterina; Grumezescu, Valentina; Holban, Alina Maria; Vasile, Bogdan Stefan; Surdu, Adrian Vasile; Grumezescu, Alexandru Mihai; Socol, Gabriel; Mogoantă, Laurenţiu; Mogoşanu, George Dan; Balaure, Paul Cătălin; Rădulescu, Radu; Chifiriuc, Mariana Carmen

    2016-06-01

    In this study, we investigated the potential of MAPLE-deposited coatings mesoporous silica nanoparticles (MSNs) to release Zinforo (ceftarolinum fosmil) in biologically active form. The MSNs were prepared by using a classic procedure with cetyltrimethylammonium bromide as sacrificial template and tetraethylorthosilicate as the monomer. The Brunauer-Emmett-Teller (BET) and transmission electron microscopy (TEM) analyses revealed network-forming granules with diameters under 100 nm and an average pore diameter of 2.33 nm. The deposited films were characterized by SEM, TEM, XRD and IR. Microbiological analyses performed on ceftaroline-loaded films demonstrated that the antibiotic was released in an active form, decreasing the microbial adherence rate and colonization of the surface. Moreover, the in vitro and in vivo assays proved the excellent biodistribution and biocompatibility of the prepared systems. Our results suggest that the obtained bioactive coatings possess a significant potential for the design of drug delivery systems and antibacterial medical-use surfaces, with great applications in bone implantology.

  19. Porous Silica-Coated Gold Nanorods: A Highly Active Catalyst for the Reduction of 4-Nitrophenol.

    PubMed

    Mohanta, Jagdeep; Satapathy, Smithsagar; Si, Satyabrata

    2016-02-03

    The successful coating of thin porous silica layers of various thicknesses [(10±1), (12±1), and (14±1) nm] on cetyl trimethylammonium bromide (CTAB) capped gold nanorods was achieved through a modified Stöber procedure. The resulting material was applied as a novel catalyst for the reduction of 4-nitrophenol. The catalytic activities of the gold nanorods increased up to eight times after coating with a layer of porous silica and the reaction followed a zero-order kinetics, having a rate constant as high as 2.92×10(-1) mol L(-1) min(-1). The spectral changes during the reduction reaction of 4-nitrophenol were observed within a very short span of time and a complete conversion to 4-aminophenol occured within 5-6 mins, including the induction period of ≈2 mins. The reusability of the catalyst was studied by running the catalytic reaction during five consecutive cycles with good efficiency without destroying the nanostructure. The methodology can be effectively applied to the development of composite catalysts with highly enhanced catalytic activity.

  20. Coating Carbon Fibers With Platinum

    NASA Technical Reports Server (NTRS)

    Effinger, Michael R.; Duncan, Peter; Coupland, Duncan; Rigali, Mark J.

    2007-01-01

    A process for coating carbon fibers with platinum has been developed. The process may also be adaptable to coating carbon fibers with other noble and refractory metals, including rhenium and iridium. The coated carbon fibers would be used as ingredients of matrix/fiber composite materials that would resist oxidation at high temperatures. The metal coats would contribute to oxidation resistance by keeping atmospheric oxygen away from fibers when cracks form in the matrices. Other processes that have been used to coat carbon fibers with metals have significant disadvantages: Metal-vapor deposition processes yield coats that are nonuniform along both the lengths and the circumferences of the fibers. The electrical resistivities of carbon fibers are too high to be compatible with electrolytic processes. Metal/organic vapor deposition entails the use of expensive starting materials, it may be necessary to use a furnace, and the starting materials and/or materials generated in the process may be hazardous. The present process does not have these disadvantages. It yields uniform, nonporous coats and is relatively inexpensive. The process can be summarized as one of pretreatment followed by electroless deposition. The process consists of the following steps: The surfaces of the fiber are activated by deposition of palladium crystallites from a solution. The surface-activated fibers are immersed in a solution that contains platinum. A reducing agent is used to supply electrons to effect a chemical reduction in situ. The chemical reduction displaces the platinum from the solution. The displaced platinum becomes deposited on the fibers. Each platinum atom that has been deposited acts as a catalytic site for the deposition of another platinum atom. Hence, the deposition process can also be characterized as autocatalytic. The thickness of the deposited metal can be tailored via the duration of immersion and the chemical activity of the solution.

  1. Nanocomposite Lanthanum Zirconate Thermal Barrier Coating Deposited by Suspension Plasma Spray Process

    NASA Astrophysics Data System (ADS)

    Wang, Chaohui; Wang, You; Wang, Liang; Hao, Guangzhao; Sun, Xiaoguang; Shan, Fan; Zou, Zhiwei

    2014-10-01

    This work seeks to develop an innovative nanocomposite thermal barrier coating (TBC) exhibiting low thermal conductivity and high durability compared with that of current TBCs. To achieve this objective, nanosized lanthanum zirconate particles were selected for the topcoat of the TBC system, and a new process—suspension plasma spray—was employed to produce desirable microstructural features: the nanocomposite lanthanum zirconate TBC contains ultrafine splats and high volume porosity, for lower thermal conductivity, and better durability. The parameters of plasma spray experiment included two main variables: (i) spray distance varying from 40 to 80 mm and (ii) the concentration of suspension 20, 25, and 30 wt.%, respectively. The microstructure of obtained coatings was characterized with scanning electron microscope and x-ray diffraction. The porosity of coatings is in the range of 6-10%, and the single phase in the as-sprayed coatings was pyrochlore lanthanum zirconate.

  2. 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.

  3. PEG-Phospholipids Coated Quantum Rods as Amplifiers of the Photosensitization Process by FRET.

    PubMed

    Timor, Reut; Weitman, Hana; Waiskopf, Nir; Banin, Uri; Ehrenberg, Benjamin

    2015-09-30

    Singlet oxygen ((1)O2) generated upon photostimulation of photosensitizer molecules is a highly reactive specie which is utilized in photodynamic therapy. Recent studies have shown that semiconductor nanoparticles can be used as donors in fluorescence resonance energy transfer (FRET) process to excite attached photosensitizer molecules. In these studies, their unique properties, such as low nanoscale size, long-term photostability, wide broad absorbance band, large absorption cross section, and narrow and tunable emission bands were used to provide advantages over the traditional methods to produce singlet oxygen. Previous studies that achieved this goal, however, showed some limitations, such as low FRET efficiency, poor colloidal stability, nonspecific interactions, and/or complex preparation procedure. In this work, we developed and characterized a novel system of semiconductor quantum rods (QRs) and the photosensitizer meso-tetra(hydroxyphenyl) chlorin (mTHPC), as a model system that produces singlet oxygen without these limitations. A simple two-step preparation method is shown; Hydrophobic CdSe/CdS QRs are solubilized in aqueous solutions by encapsulation with lecithin and PEGylated phospholipid (PEG-PL) of two lipid lengths: PEG350 or PEG2000. Then, the hydrophobic photosensitizer mTHPC, was intercalated into the new amphiphilic PEG-PL coating of the QR, providing a strong attachment to the nanoparticle without covalent linkage. These PEGylated QR (eQR)-mTHPC nanocomposites show efficient FRET processes upon light stimulation of the QR component which results in efficient production of singlet oxygen. The results demonstrate the potential for future use of this concept in photodynamic therapy schemes.

  4. Scale-Up of SLIP Process: Producing Nanoengineered Coatings at High Volumes to Meet Multi-Directorate Needs

    SciTech Connect

    O'Brien, K C; Sanders, D M; Moffitt, K C; Marquez, R; Spadaccini, C

    2005-10-27

    There are a variety of applications that require the use of nanoengineered surfaces for separation applications. Surfaces are commonly functionalized in order to facilitate the purification of gases and liquids. Functionalization often requires the application of a polymer to the surface. The most common means is to dissolve the polymer in a solvent and then either cast or spray it onto the surface. This traditional approach causes two severe limitations: (1) the polymer must be soluble; (2) the solvent must be removed from the final coating. The first limitation often eliminates many potential candidate polymers. The second limitation is influential on the transport and separation properties of the coating. Low levels of residual solvents can significantly degrade the ability of the coating to perform the separation process. These two issues can be overcome through the use of ''Solvent-Less vapor deposition followed by In-situ Polymerization'' (SLIP). The SLIP process was originally developed for the fabrication of Inertial Confinement Fusion (ICF) targets. This application required the deposition of films of 100 to 200 microns in thickness onto a spherical substrate. The process consists of two evaporation chambers each containing a quantity of monomer. The precursors, monomers, are vaporized and flow though a mixing nozzle and eventually are deposited on a substrate surface. They react at the surface and form a nanoengineered polymer film. The SLIP process has been utilized to develop composite membranes for gas and liquid separation applications. Polyimide films that range in thickness from 50 to 400 nm were deposited onto a range of substrates. The SLIP process has been shown to be robust and current plans are in place to scale-up the process. This scale-up would enable the coating of flat sheets and fibers. This paper will outline the roadmap to constructing a pilot scale SLIP system in order to meet multiple programmatic needs.

  5. 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.

  6. Process for diffusing metallic coatings into ceramics to improve their voltage withstanding capabilities

    DOEpatents

    Miller, H. Craig; Zuhr, Herbert F.

    1978-01-01

    The disclosure relates to a method for diffusing a coating of manganese powder and titanium powder into a ceramic to improve its voltage hold off withstanding capability. The powder coated ceramic is fired for from about 30 to about 90 minutes within about one atmosphere of wet hydrogen at a temperature within the range of from about 1450.degree. to about 1520.degree. C to cause the mixture to penetrate into the ceramic to a depth on the order of a millimeter.

  7. Process for Non-Contact Removal of Organic Coatings from the Surface of Paintings

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A. (Inventor); Rutledge, Sharon K. (Inventor)

    1996-01-01

    The present invention discloses a method of removing organic protective coatings from a painting. In the present invention degraded protective coatings such as lacquers, acrylics, natural resins, carbons, soot, and polyurethane are safely removed from the surface of a painting without contact to the surface of the painting. This method can be used for restoration of paintings when they have been damaged, through age, fire, etc.

  8. Process for non-contact removal of organic coatings from the surface of paintings

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A. (Inventor); Rutledge, Sharon K. (Inventor)

    1995-01-01

    The present invention discloses a method of removing organic protective coatings from a painting. In the present invention degraded protective coatings such as lacquers, acrylics, natural resins, carbons, soot, and polyurethane are safely removed from the surface of a painting without contact to the surface of the painting. This method can be used for restoration of paintings when they have been damaged, through age, fire, etc.

  9. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    DOE PAGES

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-11-06

    We have examined how different cleaning processes affect the laser-induced damage threshold of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. There is a nearly twofold increase in laser-induced damage threshold between the antireflection coatings that were cleaned and those that were not cleaned. Aging of the coatings after 4 months resulted in even higher laser-induced damage thresholds. Also, the laser-induced damage threshold results revealed that every antireflection coating had a high defectmore » density, despite the cleaning process used, which indicates that improvements to either the cleaning or deposition processes should provide even higher laser-induced damage thresholds.« less

  10. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    SciTech Connect

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-11-06

    We have examined how different cleaning processes affect the laser-induced damage threshold of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. There is a nearly twofold increase in laser-induced damage threshold between the antireflection coatings that were cleaned and those that were not cleaned. Aging of the coatings after 4 months resulted in even higher laser-induced damage thresholds. Also, the laser-induced damage threshold results revealed that every antireflection coating had a high defect density, despite the cleaning process used, which indicates that improvements to either the cleaning or deposition processes should provide even higher laser-induced damage thresholds.

  11. Process for preparing active oxide powders

    DOEpatents

    Berard, Michael F.; Hunter, Jr., Orville; Shiers, Loren E.; Dole, Stephen L.; Scheidecker, Ralph W.

    1979-02-20

    An improved process for preparing active oxide powders in which cation hydroxide gels, prepared in the conventional manner are chemically dried by alternately washing the gels with a liquid organic compound having polar characteristics and a liquid organic compound having nonpolar characteristics until the mechanical water is removed from the gel. The water-free cation hydroxide is then contacted with a final liquid organic wash to remove the previous organic wash and speed drying. The dried hydroxide treated in the conventional manner will form a highly sinterable active oxide powder.

  12. Direct Laser Processing of Tantalum Coating on Titanium for Bone Replacement Structures

    PubMed Central

    Balla, Vamsi Krishna; Banerjee, Shashwat; Bose, Susmita; Bandyopadhyay, Amit

    2010-01-01

    Recently, tantalum is gaining more attention as a new metallic biomaterial as it has been shown to be bioactive and biologically bond to the bone. However, relatively high cost of manufacture and inability to produce a modular all tantalum implant has limited'its widespread acceptance. In this study, we have successfully deposited Ta coating on Ti using Laser Engineered Net Shaping (LENS™) to enhance osseointegration properties. In vitro biocompatibility study, using human osteoblast cell line hFOB, showed excellent cellular adherence and growth with abundant extracellular matrix formation on Ta coating surface compare to Ti surface. Six times higher living cell density was observed on Ta coating than on Ti control surface during MMT assay. High surface energy and wettability of Ta surface were observed to contribute to its significantly better cell-materials interactions. Also, these dense Ta coatings do not suffer from low fatigue resistance due to the absence of porosity and sharp interface between the coating and the substrate, which is a major concern for porous coatings used for enhanced/early biological fixation. PMID:19931654

  13. Photocatalytic activity and characterization of sol-gel-derived Ni-doped TiO2-coated active carbon composites

    NASA Astrophysics Data System (ADS)

    Bhosale, R. R.; Pujari, S. R.; Lande, M. K.; Arbad, B. R.; Pawar, S. B.; Gambhire, A. B.

    2012-11-01

    Ni-doped, TiO2-coated active carbon (Ni-TiO2/AC) were prepared by a sol-gel method. The effect of supports, including TiO2 and active carbon (AC), on the molecular structure and photocatalytic activity of nickel oxide for complete decomposition of methylene blue has been examined with respect to the content of Ni on the catalyst surface. The photocatalytic activities of the Ni-TiO2/AC composites were evaluated in the decomposition of methylene blue solution under visible-light irradiation. The results indicate that Ni-TiO2/AC has a higher efficiency in decomposition of methylene blue than TiO2 and TiO2/AC. This was attributed to the different functions of active carbon and nickel species. First, nanosize TiO2 particles on composites were not reunited, possible because active carbon retards transformation of anatase into rutile and decrease the crystallite size. Second, production of high concentrations of organic compound near Ni-TiO2. Third, carbon in active carbon causes some of the TiO2 to reduce to Ti3+ ions, which prevents electron-hole pair recombination. It was found that the addition of Ni to TiO2 sol could suppress the grain growth of TiO2 crystals and increase the hydroxyl content on the surface of TiO2/AC. The photocatalytic efficiency and activity of the composites remained good, even after three cycles.

  14. Quaternized chitosan/κ-carrageenan/caffeic acid-coated poly(3-hydroxybutyrate) fibrous materials: Preparation, antibacterial and antioxidant activity.

    PubMed

    Ignatova, Milena; Manolova, Nevena; Rashkov, Iliya; Markova, Nadya

    2016-11-20

    Novel fibrous materials with antioxidant and antibacterial properties from poly(3-hydroxybutyrate) (PHB), quaternized chitosan (QCh), κ-carrageenan (Car) and caffeic acid (CA) were obtained. These materials were prepared by applying electrospinning or electrospinning in conjunction with dip-coating and polyelectrolyte complex (PEC) formation. It was found that the CA release depended on the fiber composition. X-ray diffraction analysis (XRD) and differential scanning calorimetry (DSC) revealed that CA incorporated in the fibers was in the amorphous state, whereas CA included in the coating was in the crystalline state. In contrast to the neat PHB mats, the CA-containing mats and the PEC QCh/Car-coated mats were found to kill the Gram-positive bacteria S. aureus and the Gram-negative bacteria E. coli and were effective in suppressing the adhesion of pathogenic bacteria S. aureus. Enhancement of the antioxidant activity of the fibrous materials containing both CA and QCh/Car coating was observed.

  15. Antimicrobial activity and cytotoxicity of cotton fabric coated with conducting polymers, polyaniline or polypyrrole, and with deposited silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Maráková, Nela; Humpolíček, Petr; Kašpárková, Věra; Capáková, Zdenka; Martinková, Lenka; Bober, Patrycja; Trchová, Miroslava; Stejskal, Jaroslav

    2017-02-01

    Cotton fabric was coated with conducting polymers, polyaniline or polypyrrole, in situ during the oxidation of respective monomers. Raman and FTIR spectra proved the complete coating of substrates. Polypyrrole content was 19.3 wt.% and that of polyaniline 6.0 wt.%. Silver nanoparticles were deposited from silver nitrate solutions of various concentrations by exploiting the reduction ability of conducting polymers. The content of silver was up to 11 wt.% on polypyrrole and 4 wt.% on polyaniline. The sheet resistivity of fabrics was determined. The conductivity was reduced after deposition of silver. The chemical cleaning reduced the conductivity by less than one order of magnitude for polypyrrole coating, while for polyaniline the decrease was more pronounced. The good antibacterial activity against S. aureus and E. coli and low cytotoxicity of polypyrrole-coated cotton, both with and without deposited silver nanoparticles

  16. Adhesion, cytoskeletal architecture and activation status of primary human macrophages on a diamond-like carbon coated surface.

    PubMed

    Linder, Stefan; Pinkowski, Wolfhard; Aepfelbacher, Martin

    2002-02-01

    Diamond-like carbon is a promising surface coating for biomedicinal implants like coronary stents or hip joints. Before widespread clinical use of this material, its biocompatibility has to be thoroughly assessed. Cells likely to encounter a diamond-like coated implant in the human body are cells of the monocytic lineage. Their interaction with the diamond-like carbon coated surface will probably critically influence the fate of the implant, as monocytes orchestrate inflammatory reactions and also affect osseointegration of implants. We therefore investigated adhesion, cytoarchitecture and activation status of primary human monocytes and their differentiated derivatives, macrophages, on diamond-like coated glass coverslips using immunofluorescence technique. We show that adhesion of primary monocytes to a diamond-like-coated coverslip is slightly, but not significantly, enhanced in comparison to uncoated coverslips, while the actin and microtubule cytoskeletons of mature macrophages show a normal development. The activation status of macrophages, as judged by polarization of the cell body, was not affected by growth on a diamond-like carbon surface. We conclude that diamond-like carbon shows good indications for biocompatibility to blood monocytes in vitro. It is therefore unlikely that contact with a diamond-like carbon coated surface in the human body will elicit inflammatory signals by these cells.

  17. Nanostructured titanium-silver coatings with good antibacterial activity and cytocompatibility fabricated by one-step magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Bai, Long; Hang, Ruiqiang; Gao, Ang; Zhang, Xiangyu; Huang, Xiaobo; Wang, Yueyue; Tang, Bin; Zhao, Lingzhou; Chu, Paul K.

    2015-11-01

    Bacterial infection and loosing are serious complications for biomedical implants in the orthopedic, dental, and other biomedical fields and the ideal implants should combine good antibacterial ability and bioactivity. In this study, nanostructured titanium-silver (Ti-Ag) coatings with different Ag contents (1.2 to 21.6 at%) are prepared on Ti substrates by magnetron sputtering. As the Ag concentration is increased, the coatings change from having dense columnar crystals to sparse ones and eventually no columnar structure. The Ti-Ag coatings can effectively kill Staphylococcus aureus during the first few days and remain moderately antibacterial after immersion for 75 days. Compared to pure Ti, the Ti-Ag coatings show good cytocompatibility as indicated by good osteoblast adhesion, proliferation, intracellular total protein synthesis, and alkaline phosphatase (ALP) activity. In addition, cell spreading, collagen secretion, and extracellular matrix mineralization are promoted on the coatings with the proper Ag contents due to the nanostructured morphological features. Our results indicate that favorable antibacterial activity and osseointegration ability can be simultaneously achieved by regulating the Ag contents in Ti-Ag coatings.

  18. The effect of spraying parameters on micro-structural properties of WC-12%Co coating deposited on copper substrate by HVOF process

    SciTech Connect

    Sathwara, Nishit; Jariwala, C. Chauhan, N.; Raole, P. M.; Basa, D. K.

    2015-08-28

    High Velocity Oxy-Fuel (HVOF) thermal sprayed coatingmade from Tungsten Carbide (WC) isconsidered as one of the most durable materials as wear resistance for industrial applications at room temperature. WC coating offers high wear resistance due to its high hardness and tough matrix imparts. The coating properties strongly depend on thermal spray processing parameters, surface preparation and surface finish. In this investigation, the effect of variousHVOF process parameters was studied on WC coating properties. The WC-12%Co coating was produced on Copper substrate. Prior to coating, theCopper substrate surface was prepared by grit blasting. WC-12%Co coatings were deposited on Coppersubstrates with varying process parameters such as Oxygen gas pressure, Air pressure, and spraying distance. Microstructure of coating was examined using Scanning Electron Microscope (SEM) and characterization of phasespresentin the coating was examined by X-Ray Diffraction (XRD). Microhardness of all coatingswas measured by VickerMicrohardness tester. At low Oxygen Pressure(10.00 bar), high Air pressure (7bar) and short nozzle to substrate distance of 170mm, best coating adhesion and porosity less structure isachieved on Coppersubstrate.

  19. Sodium chloride methanol solution spin-coating process for bulk-heterojunction polymer solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Tong-Fang; Hu, Yu-Feng; Deng, Zhen-Bo; Li, Xiong; Zhu, Li-Jie; Wang, Yue; Lv, Long-Feng; Wang, Tie-Ning; Lou, Zhi-Dong; Hou, Yan-Bing; Teng, Feng

    2016-08-01

    The sodium chloride methanol solution process is conducted on the conventional poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) polymer bulk heterojunction solar cells. The device exhibits a power conversion efficiency of up to 3.36%, 18% higher than that of the device without the solution process. The measurements of the active layer by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and ultraviolet photoelectron spectroscopy (UPS) indicate a slight phase separation in the vertical direction and a sodium chloride distributed island-like interface between the active layer and the cathode. The capacitance-voltage (C-V) and impedance spectroscopy measurements prove that the sodium chloride methanol process can reduce the electron injection barrier and improve the interfacial contact of polymer solar cells. Therefore, this one-step solution process not only optimizes the phase separation in the active layers but also forms a cathode buffer layer, which can enhance the generation, transport, and collection of photogenerated charge carriers in the device simultaneously. This work indicates that the inexpensive and non-toxic sodium chloride methanol solution process is an efficient one-step method for the low cost manufacturing of polymer solar cells. Project supported by the Fundamental Research Funds for the Central Universities, China (Grant No. 2014JBZ009) and the National Natural Science Foundation of China (Grant Nos. 61274063, 61377028, 61475014, and 61475017).

  20. Active voltammetric microsensors with neural signal processing.

    SciTech Connect

    Vogt, M. C.

    1998-12-11

    Many industrial and environmental processes, including bioremediation, would benefit from the feedback and control information provided by a local multi-analyte chemical sensor. For most processes, such a sensor would need to be rugged enough to be placed in situ for long-term remote monitoring, and inexpensive enough to be fielded in useful numbers. The multi-analyte capability is difficult to obtain from common passive sensors, but can be provided by an active device that produces a spectrum-type response. Such new active gas microsensor technology has been developed at Argonne National Laboratory. The technology couples an electrocatalytic ceramic-metallic (cermet) microsensor with a voltammetric measurement technique and advanced neural signal processing. It has been demonstrated to be flexible, rugged, and very economical to produce and deploy. Both narrow interest detectors and wide spectrum instruments have been developed around this technology. Much of this technology's strength lies in the active measurement technique employed. The technique involves applying voltammetry to a miniature electrocatalytic cell to produce unique chemical ''signatures'' from the analytes. These signatures are processed with neural pattern recognition algorithms to identify and quantify the components in the analyte. The neural signal processing allows for innovative sampling and analysis strategies to be employed with the microsensor. In most situations, the whole response signature from the voltammogram can be used to identify, classify, and quantify an analyte, without dissecting it into component parts. This allows an instrument to be calibrated once for a specific gas or mixture of gases by simple exposure to a multi-component standard rather than by a series of individual gases. The sampled unknown analytes can vary in composition or in concentration, the calibration, sensing, and processing methods of these active voltammetric microsensors can detect, recognize, and

  1. Proteolytic Processing Regulates Placental Growth Factor Activities*

    PubMed Central

    Hoffmann, Daniel C.; Willenborg, Sebastian; Koch, Manuel; Zwolanek, Daniela; Müller, Stefan; Becker, Ann-Kathrin A.; Metzger, Stephanie; Ehrbar, Martin; Kurschat, Peter; Hellmich, Martin; Hubbell, Jeffrey A.; Eming, Sabine A.

    2013-01-01

    Placental growth factor (PlGF) is a critical mediator of blood vessel formation, yet mechanisms of its action and regulation are incompletely understood. Here we demonstrate that proteolytic processing regulates the biological activity of PlGF. Specifically, we show that plasmin processing of PlGF-2 yields a protease-resistant core fragment comprising the vascular endothelial growth factor receptor-1 binding site but lacking the carboxyl-terminal domain encoding the heparin-binding domain and an 8-amino acid peptide encoded by exon 7. We have identified plasmin cleavage sites, generated a truncated PlGF118 isoform mimicking plasmin-processed PlGF, and explored its biological function in comparison with that of PlGF-1 and -2. The angiogenic responses induced by the diverse PlGF forms were distinct. Whereas PlGF-2 increased endothelial cell chemotaxis, vascular sprouting, and granulation tissue formation upon skin injury, these activities were abrogated following plasmin digestion. Investigation of PlGF/Neuropilin-1 binding and function suggests a critical role for heparin-binding domain/Neuropilin-1 interaction and its regulation by plasmin processing. Collectively, here we provide new mechanistic insights into the regulation of PlGF-2/Neuropilin-1-mediated tissue vascularization and growth. PMID:23645683

  2. Activation of consolidation processes of alumina ceramics

    NASA Astrophysics Data System (ADS)

    Matrenin, S. V.; Zenin, B. S.; Tayukin, R. V.

    2016-02-01

    The methods for activating sintering ceramics based on Al2O3 by mechanical activation in the planetary mill, by adding in the mixture of nanopowders (NP) Al, Al2O3, and submicron powder TiO2, and by applying the technology of spark plasma sintering (SPS) are developed. It has been shown that adding the nanopowder up to 20 wt. % Al2O3 in a coarse powder α-Al2O3 activates the sintering process resulting in increased density and hardness of the sintered alumina ceramics. Substantial effect of increasing density of alumina ceramics due to adding the submicron powder TiO2 in the compound of initial powder mixtures has been established.

  3. Ion beam processing of high-temperature solid-lubricating coatings

    SciTech Connect

    Bhattacharya, R.S.; Rai, A.K.; Yust, C.S.

    1993-07-01

    Ion bean assisted deposition (IBAD) and ion beam mixing (IBM) were utilized to fabricate self-lubricating coatings of CaF{sub 2}/Ag and BaF{sub 2}/CaF{sub 2}/Ag composites. In IBAD, a low energy ({approximately}500 eV) Ar{sup +} bombardment was used in combinations with electron beam evaporation of coating materials. In ion beam mixing, magnetron sputter deposition was used to deposit a mixed composite coating of CaF{sub 2} + Ag which was subsequently ion beam mixed with 1 MeV Ag{sup +} at a fluence of 1 x 10{sup 16} cm{sup {minus}2}. The deposited coatings were characterized for composition and microstructure using Rutherford back-scattering spectrometry (RBS) and transmission electron microscopy (TEM). The friction and wear tests were carried out in a high-temperature controlled-atmosphere test system utilizing pin-on-disc wear test geometry. Uncoated Si{sub 3}N{sub 4} (NBD-100) spheres were used as the pin-on coated NBD-100 Si{sub 3}N{sub 4} and Rene 41 Ni-base superalloy discs. Both IBAD and sputtering of BaF{sub 2} and CaF{sub 2} resulted in a near stoichiometric composition with a very fine microstructure. Friction coefficients below 600{degrees}C were approximately 0.2-0.3 in the case of coated Rene 41 alloy, but were reduced to about 0.1-0.15 at 800{degrees}C for coated Si{sub 3}N{sub 4}. 13 refs., 15 figs., 2 tabs.

  4. Improvement Characteristics of Bio-active Materials Coated Fabric on Rat Muscular Mitochondria.

    PubMed

    Lee, Donghee; Kim, Young-Won; Kim, Jung-Ha; Yang, Misuk; Bae, Hyemi; Lim, Inja; Bang, Hyoweon; Go, Kyung-Chan; Yang, Gwang-Wung; Rho, Yong-Hwan; Park, Hyo-Suk; Park, Eun-Ho; Ko, Jae-Hong

    2015-05-01

    This study surveys the improvement characteristics in old-aged muscular mitochondria by bio-active materials coated fabric (BMCF). To observe the effects, the fabric (10 and 30%) was worn to old-aged rat then the oxygen consumption efficiency and copy numbers of mitochondria, and mRNA expression of apoptosis- and mitophagy-related genes were verified. By wearing the BMCF, the oxidative respiration significantly increased when using the 30% materials coated fabric. The mitochondrial DNA copy number significantly decreased and subsequently recovered in a dose-dependent manner. The respiratory control ratio to mitochondrial DNA copy number showed a dose-dependent increment. As times passed, Bax, caspase 9, PGC-1α and β-actin increased, and Bcl-2 decreased in a dose-dependent manner. However, the BMCF can be seen to have had no effect on Fas receptor. PINK1 expression did not change considerably and was inclined to decrease in control group, but the expression was down-regulated then subsequently increased with the use of the BMCF in a dose-dependent manner. Caspase 3 increased and subsequently decreased in a dose-dependent manner. These results suggest that the BMCF invigorates mitophagy and improves mitochondrial oxidative respiration in skeletal muscle, and in early stage of apoptosis induced by the BMCF is not related to extrinsic death-receptor mediated but mitochondria-mediated signaling pathway.

  5. Active Control of Dye Release for Neuronal Tracing using PEDOT-PSS Coated Electrodes.

    PubMed

    Heizmann, Stefanie; Kilias, Antje; Ruther, Patrick; Egert, Ulrich; Asplund, Maria

    2016-10-31

    Penetrating neural probes comprising arrays of microelectrodes are commonly used to monitor local field potentials and multi-unit activity in animal brain over time frames of weeks. To correlate these recorded signals to specific tissue areas, histological analysis is performed after the experimental endpoint. Even if the lesion of the penetrating probe shaft can be observed, a precise reconstruction of the exact electrode positions is still challenging. To overcome these experimental difficulties, we developed a new concept, whereupon recording electrodes are coated with a poly (3, 4-ethylenedioxythiophene/ polystyrenesulfonate) (PEDOT/PSS)-based film. The conducting polymer acts as dye reservoir over several weeks and afterwards provides controlled delivery of neurotracers. This paper presents a recording electrode based on a PEDOT/PSS bilayer optimized for dye delivery and with reduced impedance. Controlled exchange of neurotracer dye is successfully demonstrated in vitro using spectrofluorometry and in neuroblastoma cell cultures. A second PEDOT/PSS capping layer on top of the dye reservoir lowers the passive leakage of dye by a factor of 6.4 and prevents a direct contact of the dye filled layer with the cells. Stability tests over four weeks demonstrate the electrochemical stability of the PEDOT coating, as well as retained functionality of the dye delivery system.

  6. Development of scribing process of coated conductors for reduction of AC losses

    NASA Astrophysics Data System (ADS)

    Suzuki, K.; Yoshizumi, M.; Izumi, T.; Shiohara, Y.; Iwakuma, M.; Ibi, A.; Miyata, S.; Yamada, Y.

    2008-09-01

    Coated conductors (CCs) are prospective for electric power applications intended for not only better cost performance but also high critical current density ( Jc) under magnetic fields comparing with Bi 2Sr 2Ca 2Cu 3O y (BSCCO) tapes. Furthermore, they also have a possibility to reduce AC losses by various methods of post-treatments since the CCs are of a laminated structure with the insulating buffer layers. Multifilamentation by narrowing the tape width is quite effective to reduce the AC losses and therefore this approach is valid for the standard process to fabricate practical CCs with an appropriate architecture. In this study, we developed a tape scribing technique applying a technique of YAG laser with/without chemical etching to control the filament width in YBa 2Cu 3O y (YBCO) CCs for the multifilament. The AC loss was reducible to one-twentieth by 20-multifilament structure in a short sample test, and to one-third by 3-multifilament structure in the coil using 28 m long tapes in total. The authors measured the resistance between the filaments at 60-300 K after post-treatment to investigate the effective bridged materials, which is essential for decoupling of the filaments. We improved the resistance value between the filaments at liquid nitrogen temperature up to the order of 10 Ω/cm using the YAG laser with high-temperature oxygen anneals. Furthermore, the resistance over 10 6 Ω/cm was evident by the combination of laser scribing and chemical etching, which is much higher than the requirements of all the applications.

  7. Development of a Convergent Spray Technologies(tm) Spray Process for a Solventless Sprayable Coating, MCC-1

    NASA Technical Reports Server (NTRS)

    Patel, Anil K.; Meeks, C.

    1998-01-01

    This paper discusses the application of Convergent Spray Technologies (TM) Spray Process to the development and successful implementation of Marshall Convergent Coating (MCC-1) as a primary Thermal Protection System (TPS) for the Space Shuttle Solid Rocket Boosters (SRBs). This paper discusses the environmental and process benefits of the MCC-1 technology, shows the systematic steps taken in developing the technology, including statistical sensitivity studies of about 35 variables. Based on the process and post-flight successes on the SRB, it will be seen that the technology is "field-proven". Application of this technology to other aerospace and commercial programs is summarized to illustrate the wide range of possibilities.

  8. Antibacterial Activity of Polyaniline Coated Silver Nanoparticles Synthesized from Piper Betle Leaves Extract.

    PubMed

    Mamun Or Rashida, Md; Shafiul Islam, Md; Azizul Haque, Md; Arifur Rahman, Md; Tanvir Hossain, Md; Abdul Hamid, Md

    2016-01-01

    Plants or natural resources have been found to be a good alternative method for nanoparticles synthesis. In this study, polyaniline coated silver nanoparticles (AgNPs) synthesized from Piper betle leaves extract were investigated for their antibacterial activity. Silver nanoparticles were prepared from the reduction of silver nitrate and NaBH4 was used as reducing agent. Silver nanoparticles and extracts were mixed thoroughly and then coated by polyaniline. Prepared nanoparticles were characterized by Visual inspection, Ultraviolet-visible spectroscopy (UV), Fourier transform infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) techniques. Antibacterial activities of the synthesized silver nanoparticles were tested against Staphylococcus aureus ATCC 25923, Salmonella typhi ATCC 14028, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. UV-Vis spectrum of reaction mixture showed strong absorption peak with centering at 400 nm. The FT-IR results imply that Ag-NPs were successfully synthesized and capped with bio-compounds present in P. betle. TEM image showed that Ag-NPs formed were well dispersed with a spherical structures and particle size ranging from 10 to 30 nm. The result revealed that Ag-Extract NPs showed 32.78±0.64 mm zone of inhibition against S. aureus, whereas norfloxacin (positive control) showed maximum 32.15±0.40 mm zone of inhibition for S. aureus. Again, maximum zone of inhibition 29.55±0.45 mm was found for S. typhi, 27.12±0.38 mm for E. coli and 21.95±0.45 mm for P. aeruginosa. The results obtained by this study can't be directly extrapolated to human; so further studies should be undertaken to established the strong antimicrobial activity of Ag-Extract NPs for drug development program.

  9. Antibacterial Activity of Polyaniline Coated Silver Nanoparticles Synthesized from Piper Betle Leaves Extract

    PubMed Central

    Mamun Or Rashida, Md.; Shafiul Islam, Md.; Azizul Haque, Md.; Arifur Rahman, Md.; Tanvir Hossain, Md.; Abdul Hamid, Md.

    2016-01-01

    Plants or natural resources have been found to be a good alternative method for nanoparticles synthesis. In this study, polyaniline coated silver nanoparticles (AgNPs) synthesized from Piper betle leaves extract were investigated for their antibacterial activity. Silver nanoparticles were prepared from the reduction of silver nitrate and NaBH4 was used as reducing agent. Silver nanoparticles and extracts were mixed thoroughly and then coated by polyaniline. Prepared nanoparticles were characterized by Visual inspection, Ultraviolet-visible spectroscopy (UV), Fourier transform infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) techniques. Antibacterial activities of the synthesized silver nanoparticles were tested against Staphylococcus aureus ATCC 25923, Salmonella typhi ATCC 14028, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. UV–Vis spectrum of reaction mixture showed strong absorption peak with centering at 400 nm. The FT-IR results imply that Ag-NPs were successfully synthesized and capped with bio-compounds present in P. betle. TEM image showed that Ag-NPs formed were well dispersed with a spherical structures and particle size ranging from 10 to 30 nm. The result revealed that Ag-Extract NPs showed 32.78±0.64 mm zone of inhibition against S. aureus, whereas norfloxacin (positive control) showed maximum 32.15±0.40 mm zone of inhibition for S. aureus. Again, maximum zone of inhibition 29.55±0.45 mm was found for S. typhi, 27.12±0.38 mm for E. coli and 21.95±0.45 mm for P. aeruginosa. The results obtained by this study can’t be directly extrapolated to human; so further studies should be undertaken to established the strong antimicrobial activity of Ag-Extract NPs for drug development program. PMID:27642330

  10. Antioxidant activity and bioaccessibility of phenols-enriched edible casein/caseinate coatings during in vitro digestion.

    PubMed

    Helal, Ahmed; Desobry, Stephane; Banon, Sylvie; Shamsia, Sherif M

    2015-02-01

    Active films were developed for food coating applications. Entrapped phenol susceptibility to digestion was studied. Sodium caseinate (Na-CN) coatings were formulated with 0, 10, 20% Casein (CN) incorporating selected phenols as model antioxidants. This study investigated phenol/CN/Na-CN interactions, in vitro bioaccessibility of phenols and CN role in phenols retention during in vitro gastric and pancreatic digestion. The antioxidant activity of catechin (CAT), rutin (RUT), chlorogenic acid (CHL), gallic acid (GAL), and tannic acid (TA) in coatings varied with the phenolic compound type and CN concentration and was related to phenol hydrophobic binding to CN. ABTS method gave activities ranged from 412 down to 213, and DPPH method gave values from 291·7 to 190·9. An inverse relationship was found with CN content due to CN/phenol interaction. During digestion, a part of phenols was degraded by alkaline pH of pancreatic fluid. Simultaneously, CN proteolysis led to release of phenols and the bioaccessibility index remained above 80% for all phenols. The results suggested the possibility of protecting phenols against oxidation and digestive alteration by entrapment in CN and Na-CN coating films. These positive results showed the ability to produce antioxidant-enriched edible coatings to increase food protection and phenol nutritional intake.

  11. TiO2/activated carbon fibers photocatalyst: effects of coating procedures on the microstructure, adhesion property, and photocatalytic ability.

    PubMed

    Shi, Jian-Wen; Cui, Hao-Jie; Chen, Jian-Wei; Fu, Ming-Lai; Xu, Bin; Luo, Hong-Yuan; Ye, Zhi-Long

    2012-12-15

    In order to more easily separate TiO(2) photocatalyst from the treated wastewater, TiO(2) film was immobilized on the surface of activated carbon fibers (ACFs) by employing two kinds of coating procedures, dip-coating, and hydrothermal treatment. The effects of coating procedures on microstructure of TiO(2)-coated ACFs (TiO(2)/ACFs), such as morphology, porous property, crystal structure, and light absorption characteristics were investigated in detail. The adhesion property between TiO(2) film and ACFs was evaluated by ultrasonic vibration, and the photocatalytic activity of TiO(2)/ACFs was tested by the photocatalytic decoloration of methylene blue solution. The results show that hydrothermal treatment presented many advantages to obtain high-performance TiO(2)/ACFs photocatalyst in comparison with dip-coating. Hydrothermal treatment could improve the binding property between TiO(2) films and ACFs, which endowed the as-obtained TiO(2)/ACFs photocatalyst with improved reusable performance, and TiO(2)/ACFs synthesized by hydrothermal treatment presented higher photocatalytic activity.

  12. PRESERVATION OF H2 PRODUCTION ACTIVITY IN NANOPOROUS LATEX COATINGS OF RHODOPSEUDOMONAS PALUSTRIS CGA009 DURING DRY STORAGE AT AMBIENT TEMPERATURES

    SciTech Connect

    Milliken, C.; Piskorska, M.; Soule, T.; Gosse, J.; Flickinger, M.; Smith, G.; Yeager, C.

    2012-08-27

    To assess the applicability of latex cell coatings as an "off-the-shelf' biocatalyst, the effect of osmoprotectants, temperature, humidity and O{sub 2} on preservation of H{sub 2} production in Rhodopseudomonas palustris coatings was evaluated. Immediately following latex coating coalescence (24 h) and for up to 2 weeks of dry storage, rehydrated coatings containing different osmoprotectants displayed similar rates of H{sub 2} production. Beyond 2 weeks of storage, sorbitol- treated coatings lost all H{sub 2} production activity, whereas considerable H{sub 2} production was still detected in sucrose- and trehalose-stabilized coatings. The relative humidity level at which the coatings were stored had a significant impact on the recovery and subsequent rates of H{sub 2} production. After 4 weeks storage under air at 60% humidity, coatings produced only trace amounts of H{sub 2} (0-0.1% headspace accumulation), whereas those stored at <5% humidity retained 27-53% of their H{sub 2} production activity after 8 weeks of storage. When stored in argon at <5% humidity and room temperature, R. palustris coatings retained full H{sub 2} production activity for 3 months, implicating oxidative damage as a key factor limiting coating storage. Overall, the results demonstrate that biocatalytic latex coatings are an attractive cell immobilization platform for preservation of bioactivity in the dry state.

  13. Preservation of H2 production activity in nanoporous latex coatings of Rhodopseudomonas palustris CGA009 during dry storage at ambient temperatures

    PubMed Central

    Piskorska, M; Soule, T; Gosse, J L; Milliken, C; Flickinger, M C; Smith, G W; Yeager, C M

    2013-01-01

    Summary To assess the applicability of latex cell coatings as an ‘off-the-shelf’ biocatalyst, the effect of osmoprotectants, temperature, humidity and O2 on preservation of H2 production in Rhodopseudomonas palustris coatings was evaluated. Immediately following latex coating coalescence (24 h) and for up to 2 weeks of dry storage, rehydrated coatings containing different osmoprotectants displayed similar rates of H2 production. Beyond 2 weeks of storage, sorbitol-treated coatings lost all H2 production activity, whereas considerable H2 production was still detected in sucrose- and trehalose-stabilized coatings. The relative humidity level at which the coatings were stored had a significant impact on the recovery and subsequent rates of H2 production. After 4 weeks storage under air at 60% humidity, coatings produced only trace amounts of H2 (0–0.1% headspace accumulation), whereas those stored at < 5% humidity retained 27–53% of their H2 production activity after 8 weeks of storage. When stored in argon at < 5% humidity and room temperature, R. palustris coatings retained full H2 production activity for 3 months, implicating oxidative damage as a key factor limiting coating storage. Overall, the results demonstrate that biocatalytic latex coatings are an attractive cell immobilization platform for preservation of bioactivity in the dry state. PMID:23331993

  14. Designing of Single Walled Carbon Nanotubes dispersions for industrial scale processing and roll-to-roll coating applications

    NASA Astrophysics Data System (ADS)

    Dan, Budhadipta; Pasquali, Matteo

    2009-03-01

    Carbon nanotubes (CNTs) combine nanoscale size with high aspect ratio and unique properties, making them ideal candidate materials for high-impact applications. Yet, much as in polymer science and engg, such applications require appropriate fluid based dispersions which can undergo industrial processing that translate the properties of elemental molecules (SWNTs) into macroscopic materials. We report a detailed study on the flow behavior of aqueous SWNT dispersions involving surfactants, its dependence on SWNT & surfactant concentration, and type of surfactant. We also design a SWNT dispersion for use in industrial roll-to-roll (rod based) thin film coating process. Purified, pristine SWNTs were dispersed in water at high concentrations using surfactants and analyzed using rheology and optical microscopy. A SWNT-SDBS-TritonX100 dispersion was found to have the appropriate viscoelastic and shear thinning behavior for rod coating. Rod coating, washing and sulfuric acid treatment resulted in highly uniform thin films of pure SWNT (sheet resistance of 100 and 300 φ/sq for respective transparency of 70% and 90%). The results presented here, both in terms of scientific understanding of how to control fluid and process, and in terms of a scalable technique, paves the way to the deployment of transparent conductive SWNT films in large scale commercial applications.

  15. Effect of HVOF Processing Parameters on the Properties of NiCoCrAlY Coatings by Design of Experiments

    NASA Astrophysics Data System (ADS)

    Ruiz-Luna, H.; Lozano-Mandujano, D.; Alvarado-Orozco, J. M.; Valarezo, A.; Poblano-Salas, C. A.; Trápaga-Martínez, L. G.; Espinoza-Beltrán, F. J.; Muñoz-Saldaña, J.

    2014-08-01

    The effect of three principal, independent, high-velocity oxygen fuel (HVOF)-processing parameters on the properties of NiCoCrAlY coatings deposited using commercial powders is reported here. The design of experiments (DoE) technique at a two-level factorial and a central composite rotatable design was used to analyze and optimize the HVOF spraying process. The deposition parameters investigated were (1) fuel flow, (2) oxygen flow, and (3) stand-off distance. The effect of these processing variables was evaluated using selected responses, including porosity and oxide content, residual stresses, and deposition efficiency. Coatings with low porosity as well as with low residual stress were obtained using high fuel-rich conditions at a stand-off distance between 250 and 300 mm. At shorter and longer stand-off distances, respectively, either excessive flattening of splats or un-molten condition occurred, resulting in high levels of porosity and residual stress. The response surface, the empirical relationships among the variables, and the response parameters allowed the selection of optimum deposition parameters and the improvement of coating properties.

  16. Edible Active Coatings Based on Pectin, Pullulan, and Chitosan Increase Quality and Shelf Life of Strawberries (Fragaria ananassa).

    PubMed

    Treviño-Garza, Mayra Z; García, Santos; del Socorro Flores-González, Ma; Arévalo-Niño, Katiushka

    2015-08-01

    Edible active coatings (EACs) based on pectin, pullulan, and chitosan incorporated with sodium benzoate and potassium sorbate were employed to improve the quality and shelf life of strawberries. Fruits were washed, disinfected, coated by dipping, packed, and stored at 4 °C for 15 d. Application of EACs reduced (P < 0.05) weight loss and fruit softening and delayed alteration of color (redness) and total soluble solids content. In contrast, pH and titratable acidity were not affected (P > 0.05) throughout storage, and ascorbic acid content was maintained in pectin-EAC coated strawberries. Microbiological analyses showed that application of EACs reduced (P < 0.05) microbial growth (total aerobic counts, molds, and yeasts) on strawberries. Chitosan-EAC coated strawberries presented the best results in microbial growth assays. Sensory quality (color, flavor, texture, and acceptance) improved and decay rate decreased (P < 0.05) in pectin-EAC, pullulan-EAC, and chitosan-EAC coated strawberries. In conclusion, EACs based on polysaccharides improved the physicochemical, microbiological, and sensory characteristics, increasing the shelf life of strawberries from 6 (control) to 15 d (coated fruits).

  17. Semi-active control of piezoelectric coating's underwater sound absorption by combining design of the shunt impedances

    NASA Astrophysics Data System (ADS)

    Sun, Yang; Li, Zhaohui; Huang, Aigen; Li, Qihu

    2015-10-01

    Piezoelectric shunt damping technology has been applied in the field of underwater sound absorption in recent years. In order to achieve broadband echo reduction, semi-active control of sound absorption of multi-layered piezoelectric coating by shunt damping is significant. In this paper, a practical method is proposed to control the underwater sound absorption coefficients of piezoelectric coating layers by combining design of the shunt impedance that allows certain sound absorption coefficients at setting frequencies. A one-dimensional electro-acoustic model of the piezoelectric coating and the backing is established based on the Mason equivalent circuit theory. First, the shunt impedance of the coating is derived under the constraint of sound absorption coefficient at one frequency. Then, taking the 1-3 piezoelectric composite coating as an example, the sound absorption properties of the coating shunted to the designed shunt impedance are investigated. Next, on the basis of that, an iterative method for two constrained frequencies and an optimizing algorithm for multiple constrained frequencies are provided for combining design of the shunt impedances. At last, an experimental sample with four piezoelectric material layers is manufactured, of which the sound absorption coefficients are measured in an impedance tube. The experimental results show good agreement with the finite element simulation results. It is proved that a serial R-L circuit can control the peak frequency, maximum and bandwidth of the sound absorption coefficient and the combining R-L circuits shunted to multiple layers can control the sound absorption coefficients at multiple frequencies.

  18. Biological Activity of Mesoporous Dendrimer-Coated Titanium Dioxide: Insight on the Role of the Surface-Interface Composition and the Framework Crystallinity.

    PubMed

    Milowska, Katarzyna; Rybczyńska, Aneta; Mosiolek, Joanna; Durdyn, Joanna; Szewczyk, Eligia M; Katir, Nadia; Brahmi, Younes; Majoral, Jean-Pierre; Bousmina, Mosto; Bryszewska, Maria; El Kadib, Abdelkrim

    2015-09-16

    Hitherto, the field of nanomedicine has been overwhelmingly dominated by the use of mesoporous organosilicas compared to their metal oxide congeners. Despite their remarkable reactivity, titanium oxide-based materials have been seldom evaluated and little knowledge has been gained with respect to their "structure-biological activity" relationship. Herein, a fruitful association of phosphorus dendrimers (both "ammonium-terminated" and "phosphonate-terminated") and titanium dioxide has been performed by means of the sol-gel process, resulting in mesoporous dendrimer-coated nanosized crystalline titanium dioxide. A similar organo-coating has been reproduced using single branch-mimicking dendrimers that allow isolation of an amorphous titanium dioxide. The impact of these materials on red blood cells was evaluated by studying cell hemolysis. Next, their cytotoxicity toward B14 Chinese fibroblasts and their antimicrobial activity were also investigated. Based on their variants (cationic versus anionic terminal groups and amorphous versus crystalline titanium dioxide phase), better understanding of the role of the surface-interface composition and the nature of the framework has been gained. No noticeable discrimination was observed for amorphous and crystalline material. In contrast, hemolysis and cytotoxicity were found to be sensitive to the nature of the interface composition, with the ammonium-terminated dendrimer-coated titanium dioxide being the most hemolytic and cytotoxic material. This surface-functionalization opens the door for creating a new synergistic machineries mechanism at the cellular level and seems promising for tailoring the biological activity of nanosized organic-inorganic hybrid materials.

  19. Active PZT fibers: a commercial production process

    NASA Astrophysics Data System (ADS)

    Strock, Harold B.; Pascucci, Marina R.; Parish, Mark V.; Bent, Aaron A.; Shrout, Thomas R.

    1999-07-01

    Lead Zirconate Titanate (PZT) active fibers, from 80 to 250 micrometers in diameter, are produced for the AFOSR/DARPA funded Active Fiber Composites Consortium (AFCC) Program and commercial customers. CeraNova has developed a proprietary ceramics-based technology to produce PZT mono-filaments of the required purity, composition, straightness, and piezoelectric properties for use in active fiber composite structures. CeraNova's process begins with the extrusion of continuous lengths of mono-filament precursor fiber from a plasticized mix of PZT-5A powder. The care that must be taken to avoid mix contamination is described using illustrations form problems experiences with extruder wear and metallic contamination. Corrective actions are described and example microstructures are shown. The consequences of inadequate lead control are also shown. Sintered mono- filament mechanical strength and piezoelectric properties data approach bulk values but the validity of such a benchmark is questioned based on variable correlation with composite performance measures. Comb-like ceramic preform structures are shown that are being developed to minimize process and handling costs while maintaining the required mono-filament straightness necessary for composite fabrication. Lastly, actuation performance data are presented for composite structures fabricated and tested by Continuum Control Corporation. Free strain actuation in excess of 2000 microstrain are observed.

  20. CVD aluminiding process for producing a modified platinum aluminide bond coat for improved high temperature performance

    NASA Technical Reports Server (NTRS)

    Nagaraj, Bangalore A. (Inventor); Williams, Jeffrey L. (Inventor)

    2003-01-01

    A method of depositing by chemical vapor deposition a modified platinum aluminide diffusion coating onto a superalloy substrate comprising the steps of applying a layer of a platinum group metal to the superalloy substrate; passing an externally generated aluminum halide gas through an internal gas generator which is integral with a retort, the internal gas generator generating a modified halide gas; and co-depositing aluminum and modifier onto the superalloy substrate. In one form, the modified halide gas is hafnium chloride and the modifier is hafnium with the modified platinum aluminum bond coat comprising a single phase additive layer of platinum aluminide with at least about 0.5 percent hafnium by weight percent and about 1 to about 15 weight percent of hafnium in the boundary between a diffusion layer and the additive layer. The bond coat produced by this method is also claimed.

  1. Development of a Process Analytical Technology (PAT) for in-line monitoring of film thickness and mass of coating materials during a pan coating operation.

    PubMed

    Gendre, Claire; Genty, Muriel; Boiret, Mathieu; Julien, Marc; Meunier, Loïc; Lecoq, Olivier; Baron, Michel; Chaminade, Pierre; Péan, Jean Manuel

    2011-07-17

    The aim of this study was to perform in-line Near Infrared (NIR) measurements inside a pan coater to monitor a coating operation in real-time, by predicting the increases in mass of coating materials and coating thickness. A polymer combination of ethylcellulose/poly(vinyl-alcohol)-poly(ethylene-glycol) graft copolymer was used as functional aqueous coating. Coated tablets were sampled at regular intervals during the coating operation, then subjected to either simple and fast weighing (n=50) or accurate and non-destructive Terahertz Pulsed Imaging (TPI) measurements (n=3). Off-line NIR spectra analysis revealed that the coating operation could efficiently be controlled by focusing on two distinct NIR regions, related to absorption bands of ethylcellulose. Principal component analysis of in-line NIR spectra gave a clear classification of the collected coated tablets. Real-time quantitative monitoring of the coating operation was successfully performed from partial least square calibration models built using either TPI or weighing as reference method. Coating thicknesses as well as mass of coating materials used as primary values provided accurate NIR predictions. A comparison study demonstrated that both reference methods led to reliable and accurate real-time monitoring of the coating operation. This work demonstrated that in-line NIR measurements associated with multivariate analyses can be implemented to monitor in real-time a pan coating operation in order to fulfil the expectations of ICH Q8 guideline on pharmaceutical development, especially in terms of PAT control strategy and reduced end-product testing.

  2. Imaging Active Surface Processes in Barnacle Adhesive Interfaces.

    PubMed

    Golden, Joel P; Burden, Daniel K; Fears, Kenan P; Barlow, Daniel E; So, Christopher R; Burns, Justin; Miltenberg, Benjamin; Orihuela, Beatriz; Rittshof, Daniel; Spillmann, Christopher M; Wahl, Kathryn J; Tender, Leonard M

    2016-01-19

    Surface plasmon resonance imaging (SPRI) and voltammetry were used simultaneously to monitor Amphibalanus (=Balanus) amphitrite barnacles reattached and grown on gold-coated glass slides in artificial seawater. Upon reattachment, SPRI revealed rapid surface adsorption of material with a higher refractive index than seawater at the barnacle/gold interface. Over longer time periods, SPRI also revealed secretory activity around the perimeter of the barnacle along the seawater/gold interface extending many millimeters beyond the barnacle and varying in shape and region with time. Ex situ experiments using attenuated total reflectance infrared (ATR-IR) spectroscopy confirmed that reattachment of barnacles was accompanied by adsorption of protein to surfaces on similar time scales as those in the SPRI experiments. Barnacles were grown through multiple molting cycles. While the initial reattachment region remained largely unchanged, SPRI revealed the formation of sets of paired concentric rings having alternately darker/lighter appearance (corresponding to lower and higher refractive indices, respectively) at the barnacle/gold interface beneath the region of new growth. Ex situ experiments coupling the SPRI imaging with optical and FTIR microscopy revealed that the paired rings coincide with molt cycles, with the brighter rings associated with regions enriched in amide moieties. The brighter rings were located just beyond orifices of cement ducts, consistent with delivery of amide-rich chemistry from the ducts. The darker rings were associated with newly expanded cuticle. In situ voltammetry using the SPRI gold substrate as the working electrode revealed presence of redox active compounds (oxidation potential approx 0.2 V vs Ag/AgCl) after barnacles were reattached on surfaces. Redox activity persisted during the reattachment period. The results reveal surface adsorption processes coupled to the complex secretory and chemical activity under barnacles as they construct

  3. Application of statistical experimental design to study the formulation variables influencing the coating process of lidocaine liposomes.

    PubMed

    González-Rodríguez, M L; Barros, L B; Palma, J; González-Rodríguez, P L; Rabasco, A M

    2007-06-07

    In this paper, we have used statistical experimental design to investigate the effect of several factors in coating process of lidocaine hydrochloride (LID) liposomes by a biodegradable polymer (chitosan, CH). These variables were the concentration of CH coating solution, the dripping rate of this solution on the liposome colloidal dispersion, the stirring rate, the time since the liposome production to the liposome coating and finally the amount of drug entrapped into liposomes. The selected response variables were drug encapsulation efficiency (EE, %), coating efficiency (CE, %) and zeta potential. Liposomes were obtained by thin-layer evaporation method. They were subsequently coated with CH according the experimental plan provided by a fractional factorial (2(5-1)) screening matrix. We have used spectroscopic methods to determine the zeta potential values. The EE (%) assay was carried out in dialysis bags and the brilliant red probe was used to determine CE (%) due to its property of forming molecular complexes with CH. The graphic analysis of the effects allowed the identification of the main formulation and technological factors by the analysis of the selected responses and permitted the determination of the proper level of these factors for the response improvement. Moreover, fractional design allowed quantifying the interactions between the factors, which will consider in next experiments. The results obtained pointed out that LID amount was the predominant factor that increased the drug entrapment capacity (EE). The CE (%) response was mainly affected by the concentration of the CH solution and the stirring rate, although all the interactions between the main factors have statistical significance.

  4. Dual cure low-VOC coating process. Final technical report, Phase 3

    SciTech Connect

    Kinzer, K.E.

    1993-12-01

    US EPA is implementing increasingly stringent environmental regulations on the emissions of volatile organic compounds (VOCs), which amount to about 7 {times} 10{sup 9} lb/year, largely from paints and other coating systems in industry. Objective of this project is to develop Dual Cure Photocatalyst coating technology for aerospace topcoats (urethane/acrylate), aerospace primers (epoxy/acrylate), and solventless tape backings. Some problems (moisture etc.) were encountered in the primer area. Cost, economic, and energy analyses were conducted. The dual cure technology has already been commercialized in 3M`s flexible diamond resin products. Tabs.

  5. Synthesis of ZnO coated multi-walled carbon nanotubes and their antibacterial activities.

    PubMed

    Sui, Minghao; Zhang, Lingdian; Sheng, Li; Huang, Shuhang; She, Lei

    2013-05-01

    ZnO coated multi-walled carbon nanotubes (ZnO/MWCNTs) were prepared and evaluated for their application potentials as an antimicrobial material for simultaneous concentrating and inactivating pathogenic bacteria. X-ray energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectra (XPS) were used to characterize the ZnO/MWCNTs. Escherichia coli (E. coli) was employed as the target bacterium. Comparing with the raw and the purified MWCNTs (r-MWCNTs and p-MWCNTs), which have been reported to possess antibacterial activity towards E. coli, ZnO/MWCNTs exhibited stronger antibacterial ability. The deposited ZnO was suggested to play an important role in the bactericidal action of ZnO/MWCNTs, while, the r-MWCNTs and p-MWCNTs served as more like adsorbing materials for E. coli.

  6. An Alternative Low-Cost Process for Deposition of MCrAlY Bond Coats for Advanced Syngas/Hydrogen Turbine Applications

    SciTech Connect

    Zhang, Ying

    2015-09-11

    The objective of this project was to develop and optimize MCrAlY bond coats for syngas/hydrogen turbine applications using a low-cost electrolytic codeposition process. Prealloyed CrAlY-based powders were codeposited into a metal matrix of Ni, Co or Ni-Co during the electroplating process, and a subsequent post-deposition heat treatment converted it to the MCrAlY coating. Our research efforts focused on: (1) investigation of the effects of electro-codeposition configuration and parameters on the CrAlY particle incorporation in the NiCo-CrAlY composite coatings; (2) development of the post-deposition heat treating procedure; (3) characterization of coating properties and evaluation of coating oxidation performance; (4) exploration of a sulfurfree electroplating solution; (5) cost analysis of the present electrolytic codeposition process. Different electro-codeposition configurations were investigated, and the rotating barrel system demonstrated the capability of depositing NiCo-CrAlY composite coatings uniformly on the entire specimen surface, with the CrAlY particle incorporation in the range 37-42 vol.%. Post-deposition heat treatment at 1000-1200 °C promoted interdiffusion between the CrAlY particles and the Ni-Co metal matrix, resulting in β/γ’/γ or β/γ’ phases in the heat-treated coatings. The results also indicate that the post-deposition heat treatment should be conducted at temperatures ≤1100 °C to minimize Cr evaporation and outward diffusion of Ti. The electro-codeposited NiCrAlY coatings in general showed lower hardness and surface roughness than thermal spray MCrAlY coatings. Coating oxidation performance was evaluated at 1000-1100 °C in dry and wet air environments. The initial electro-codeposited NiCoCrAlY coatings containing relatively high sulfur did not show good oxidation resistance. After modifications of the coating process, the cleaner NiCoCrAlY coating exhibited good oxidation performance at 1000 °C during the 2,000 1-h cyclic

  7. Chitosan acetate as an active coating material and its effects on the storing of Prunus avium L.

    PubMed

    Dang, Qi Feng; Yan, Jing Quan; Li, Yan; Cheng, Xiao Jie; Liu, Cheng Sheng; Chen, Xi Guang

    2010-03-01

    In this article, chitosan acetate (CA) was prepared by the method of solid-liquid reaction. CA was a stable faint yellow powder with water solubility. CA kept the same backbone in the chemical structure as the raw material of chitosan, and it also had the similar antibacterial properties with chitosan. CA could form a coating film on the outside surface of the sweet cherries, could effectively retard the loss of the water, titratable acidity, and ascorbic acid of sweet cherries, and could induce a significant increase in the peroxidase and catalase activities in the fruit. The CA coating could also increase the ratio of the total soluble solids and titratable acidity in the fruit. The application of CA effectively maintained quality attributes and extended postharvest life of the sweet cherries. The results revealed that the CA salts had potential application in active edible coating materials in the storage of fresh fruit.

  8. Design of sustained release fine particles using two-step mechanical powder processing: particle shape modification of drug crystals and dry particle coating with polymer nanoparticle agglomerate.

    PubMed

    Kondo, Keita; Ito, Natsuki; Niwa, Toshiyuki; Danjo, Kazumi

    2013-09-10

    We attempted to prepare sustained release fine particles using a two-step mechanical powder processing method; particle-shape modification and dry particle coating. First, particle shape of bulk drug was modified by mechanical treatment to yield drug crystals suitable for the coating process. Drug crystals became more rounded with increasing rotation speed, which demonstrates that powerful mechanical stress yields spherical drug crystals with narrow size distribution. This process is the result of destruction, granulation and refinement of drug crystals. Second, the modified drug particles and polymer coating powder were mechanically treated to prepare composite particles. Polymer nanoparticle agglomerate obtained by drying poly(meth)acrylate aqueous dispersion was used as a coating powder. The porous nanoparticle agglomerate has superior coating performance, because it is completely deagglomerated under mechanical stress to form fine fragments that act as guest particles. As a result, spherical drug crystals treated with porous agglomerate were effectively coated by poly(meth)acrylate powder, showing sustained release after curing. From these findings, particle-shape modification of drug crystals and dry particle coating with nanoparticle agglomerate using a mechanical powder processor is expected as an innovative technique for preparing controlled-release coated particles having high drug content and size smaller than 100 μm.

  9. Calcium phosphate/porous silicon biocomposites prepared by cyclic deposition methods: spin coating vs electrochemical activation.

    PubMed

    Hernandez-Montelongo, J; Gallach, D; Naveas, N; Torres-Costa, V; Climent-Font, A; García-Ruiz, J P; Manso-Silvan, M

    2014-01-01

    Porous silicon (PSi) provides an excellent platform for bioengineering applications due to its biocompatibility, biodegradability, and bioresorbability. However, to promote its application as bone engineering scaffold, deposition of calcium phosphate (CaP) ceramics in its hydroxyapatite (HAP) phase is in progress. In that sense, this work focuses on the synthesis of CaP/PSi composites by means of two different techniques for CaP deposition on PSi: Cyclic Spin Coating (CSC) and Cyclic Electrochemical Activation (CEA). Both techniques CSC and CEA consisted on alternate Ca and P deposition steps on PSi. Each technique produced specific morphologies and CaP phases using the same independent Ca and P stem-solutions at neutral pH and at room temperature. The brushite (BRU) phase was favored with the CSC technique and the hydroxyapatite (HAP) phase was better synthesized using the CEA technique. Analyses by elastic backscattering spectroscopy (EBS) on CaP/PSi structures synthesized by CEA supported that, by controlling the CEA parameters, an HAP coating with the required Ca/P atomic ratio of 1.67 can be promoted. Biocompatibility was evaluated by bone-derived progenitor cells, which grew onto CaP/PSi prepared by CSC technique with a long-shaped actin cytoskeleton. The density of adhered cells was higher on CaP/PSi prepared by CEA, where cells presented a normal morphological appearance and active mitosis. These results can be used for the design and optimization of CaP/PSi composites with enhanced biocompatibility for bone-tissue engineering.

  10. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    NASA Astrophysics Data System (ADS)

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-12-01

    We have examined how three different cleaning processes affect the laser-induced damage threshold (LIDT) of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. Coatings that received cleaning exhibited the highest LIDTs compared to coatings that were not cleaned. In some cases, there is nearly a twofold increase in the LIDT between the cleaned and uncleaned coatings (19.4 J/cm2 compared to 39.1 J/cm2). Higher LIDTs were realized after 4 months of aging. The most effective cleaning process involved washing the coated surface with mild detergent, and then soaking the optic in a mixture of ethyl alcohol and deionized water. Also, the laser damage results indicate that the presence of nonpropagating (NP) damage sites dominates the LIDTs of almost every optic, despite the cleaning process used. NP damage sites can be attributed to defects such as nodules in the coating or surface contamination, which suggests that pursuing further improvements to the deposition or cleaning processes are worthwhile to achieve even higher LIDTs.

  11. Iridium Oxide Coatings with Templated Porosity as Highly Active Oxygen Evolution Catalysts: Structure-Activity Relationships.

    PubMed

    Bernicke, Michael; Ortel, Erik; Reier, Tobias; Bergmann, Arno; Ferreira de Araujo, Jorge; Strasser, Peter; Kraehnert, Ralph

    2015-06-08

    Iridium oxide is the catalytic material with the highest stability in the oxygen evolution reaction (OER) performed under acidic conditions. However, its high cost and limited availability demand that IrO2 is utilized as efficiently as possible. We report the synthesis and OER performance of highly active mesoporous IrO2 catalysts with optimized surface area, intrinsic activity, and pore accessibility. Catalytic layers with controlled pore size were obtained by soft-templating with micelles formed from amphiphilic block copolymers poly(ethylene oxide)-b-poly(butadiene)-b-poly(ethylene oxide). A systematic study on the influence of the calcination temperature and film thickness on the morphology, phase composition, accessible surface area, and OER activity reveals that the catalytic performance is controlled by at least two independent factors, that is, accessible surface area and intrinsic