Pulse electrodeposition of self-lubricating Ni-W/PTFE nanocomposite coatings on mild steel surface

NASA Astrophysics Data System (ADS)

Sangeetha, S.; Kalaignan, G. Paruthimal; Anthuvan, J. Tennis

2015-12-01

Ni-W/PTFE nanocomposite coatings with various contents of PTFE (polytetafluoroethylene) particles were prepared by pulse current (PC) electrodeposition from the Ni-W plating bath containing self lubricant PTFE particles to be co-deposited. Co-deposited PTFE particulates were uniformly distributed in the Ni-W alloy matrix. The coatings were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), X-ray Diffractometry (XRD) and Vicker's micro hardness tester. Tafel Polarization and electrochemical Impedance methods were used to evaluate the corrosion resistance behaviour of the nanocomposite coatings in 3.5% NaCl solution. It was found that, the Ni-W/PTFE nanocomposite coating has better corrosion resistance than the Ni-W alloy coating. Surface roughness and friction coefficient of the coated samples were assessed by Mitutoyo Surftest SJ-310 (ISO1997) and Scratch tester TR-101-M4 respectively. The contact angle (CA) of a water droplet on the surface of nanocomposite coating was measured by Optical Contact Goniometry (OCA 35). These results indicated that, the addition of PTFE in the Ni-W alloy matrix has resulted moderate microhardness, smooth surface, less friction coefficient, excellent water repellency and enhanced corrosion resistance of the nanocomposite coatings.

Laser engineered multilayer coating of biphasic calcium phosphate/titanium nanocomposite on metal substrates.

PubMed

Zhang, Martin Yi; Ye, Chang; Erasquin, Uriel Joseph; Huynh, Toan; Cai, Chengzhi; Cheng, Gary J

2011-02-01

In this work, laser coating of biphasic calcium phosphate/titanium (BCP/Ti) nanocomposite on Ti-6Al-4 V substrates was developed. A continuous wave neodymium-doped yttrium aluminium garnet (Nd:YAG) laser was used to form a robust multilayer of BCP/Ti nanocomposite starting from hydroxyapatite and titanium nanoparticles. In this process, low power coating is realized because of the strong laser-nanoparticle interaction and good sinterability of nanosized titanium. To guide the optimization of laser processing conditions for the coating process, a multiphysics model coupling electromagnetic module with heat transfer module was developed. This model was validated by laser coating experiments. Important features of the coated samples, including microstructures, chemical compositions, and interfacial bonding strength, were characterized. We found that a multilayer of BCP, consisting of 72% hydroxyapatite (HA) and 28% beta-tricalcium phosphate (β-TCP), and titanium nanocomposite was formed on Ti-6Al-4 V substrates. Significantly, the coating/substrate interfacial bonding strength was found to be two times higher than that of the commercial plasma sprayed coatings. Preliminary cell culture studies showed that the resultant BCP/Ti nanocomposite coating supported the adhesion and proliferation of osteoblast-like UMR-106 cells.

Ag/C:F Antibacterial and hydrophobic nanocomposite coatings

NASA Astrophysics Data System (ADS)

Kylián, Ondřej; Kratochvíl, Jiří; Petr, Martin; Kuzminova, Anna; Slavínská, Danka; Biederman, Hynek; Beranová, Jana

Silver-based nanomaterials that exhibit antibacterial character are intensively studied as they represent promising weapon against multi-drug resistant bacteria. Equally important class of materials represent coatings that have highly water repellent nature. Such materials may be used for fabrication of anti-fogging or self-cleaning surfaces. The aim of this study is to combine both of these valuable material characteristics. Antibacterial and highly hydrophobic Ag/C:F nanocomposite films were fabricated by means of gas aggregation source of Ag nanoparticles and sputter deposition of C:F matrix. The nanocomposite coatings had three-layer structure C:F base layer/Ag nanoparticles/C:F top layer. It is shown that the increasing number of Ag nanoparticles in produced coatings leads not only in enhancement of their antibacterial activity, but also causes substantial increase of their hydrophobicity. Under optimized conditions, the coatings are super-hydrophobic with water contact angle equal to 165∘ and are capable to induce 6-log reduction of bacteria presented in solution within 4h.

Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool

PubMed Central

Fox-Rabinovich, German; Locks Junior, Edinei; Stolf, Pietro; Matos Martins, Marcelo

2018-01-01

In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si3N4 nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds. PMID:29495620

Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool.

PubMed

Paiva, Jose Mario; Fox-Rabinovich, German; Locks Junior, Edinei; Stolf, Pietro; Seid Ahmed, Yassmin; Matos Martins, Marcelo; Bork, Carlos; Veldhuis, Stephen

2018-02-28

In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si₃N₄ nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds.

Stress development in particulate, nano-composite and polymeric coatings

NASA Astrophysics Data System (ADS)

Jindal, Karan

2009-12-01

The main goal of this research is to study the stress, structural and mechanical property development during the drying of particulate coatings, nano-composite coatings and VOC compliant refinish clearcoats. The results obtained during this research establish the mechanism for the stress development during drying in various coating systems. Coating stress was measured using a controlled environment stress apparatus based on cantilever deflection principle. The stress evolution in alumina coatings made of 0.4 mum size alumina particles was studied and the effect of a lateral drying was investigated. The stress does not develop until the later stages of drying. A peak stress was observed during drying and the peak stress originates due to the formation of pendular rings between the particles. Silica nanocomposite coatings were fabricated from suspension of nano sized silicon dioxide particles (20 nm) and polyvinyl alcohol (PVA) polymer. The stress in silica nano-composite goes through maximum as the amount of polymer in the coating increases. The highest final stress was found to be ˜ 110MPa at a PVA content of 60 wt%. Observations from SEM, nitrogen gas adsorption, camera imaging, and nano-indentation were also studied to correlate the coatings properties during drying to measured stress. A model VOC compliant two component (2K) acrylic-polyol refinish clearcoat was prepared to study the effects of a new additive on drying, curing, rheology and stress development at room temperature. Most of the drying of the low VOC coatings occurred before appreciable (20%) crosslinking. Tensile stress developed in the same timeframe as drying and then relaxed over a longer time scale. Model low VOC coatings prepared with the additive had higher peak stresses than those without the additive. In addition, rheological data showed that the additive resulted in greater viscosity buildup during drying.

Corrosion Protection Properties of PPy-ND Composite Coating: Sonoelectrochemical Synthesis and Design of Experiment

NASA Astrophysics Data System (ADS)

Ashassi-Sorkhabi, H.; Bagheri, R.; Rezaei-Moghadam, B.

2016-02-01

In this research, the nanocomposite coatings comprising the polypyrrole-nanodiamond, PPy-ND, on St-12 steel electrodes were electro-synthesized using in situ polymerization process under ultrasonic irradiation. The corrosion protection performance and morphology characterization of prepared coatings were investigated by electrochemical methods and scanning electron microscopy, SEM, respectively. Also, the experimental design was employed to determine the best values considering the effective parameters such as the concentration of nanoparticles, the applied current density and synthesis time to achieve the most protective films. A response surface methodology, RSM, involving a central composite design, CCD, was applied to the modeling and optimization of the PPy-ND nanocomposite deposition. Pareto graphic analysis of the parameters indicated that the applied current density and some of the interactions were effective on the response. The electrochemical results proved that the embedment of diamond nanoparticle, DNP, improves the corrosion resistance of PPy coatings significantly. Therefore, desirable correlation exists between predicted data and experimental results.

Novel multifunctional titania-silica-lanthanum phosphate nanocomposite coatings through an all aqueous sol-gel process.

PubMed

Smitha, Venu Sreekala; Jyothi, Chembolli Kunhatta; Peer, Mohamed A; Pillai, Saju; Warrier, Krishna Gopakumar

2013-04-07

A novel nanocomposite coating containing titania, silica and lanthanum phosphate prepared through an all aqueous sol-gel route exhibits excellent self-cleaning ability arising from the synergistic effect of the constituents in the nanocomposite. A highly stable titania-silica-lanthanum phosphate nanocomposite sol having particle size in the range of 30-50 nm has been synthesized starting from a titanyl sulphate precursor, which was further used for the development of photocatalytically active composite coatings on glass. The coatings prepared by the dip coating technique as well as the nanocomposite powders are heat treated and characterized further for their morphology and multifunctionality. The nanocomposite containing 1.5 wt% LaPO4 has shown a surface area as high as 138 m(2) g(-1) and a methylene blue degradation efficiency of 94% in two hours of UV exposure. The composite coating has shown very good homogeneity evidenced by transparency as high as 99.5% and low wetting behaviour. The present novel approach for energy conserving, aqueous derived, self-cleaning coatings may be suitable for large scale industrial applications.

Cationic Reduced Graphene Oxide as Self-Aligned Nanofiller in the Epoxy Nanocomposite Coating with Excellent Anticorrosive Performance and Its High Antibacterial Activity.

PubMed

Luo, Xiaohu; Zhong, Jiawen; Zhou, Qiulan; Du, Shuo; Yuan, Song; Liu, Yali

2018-05-30

The design and preparation of an excellent corrosion protection coating is still a grand challenge and is essential for large-scale practical application. Herein, a novel cationic reduced graphene oxide (denoted as RGO-ID + )-based epoxy coating was fabricated for corrosion protection. RGO-ID + was synthesized by in situ synthesis and salification reaction, which is stable dispersion in water and epoxy latex, and the self-aligned RGO-ID + -reinforced cathodic electrophoretic epoxy nanocomposite coating (denoted as RGO-ID + coating) at the surface of metal was prepared by electrodeposition. The self-alignment of RGO-ID + in the coatings is mainly attributed to the electric field force. The significantly enhanced anticorrosion performance of RGO-ID + coating is proved by a series of electrochemical measurements in different concentrated NaCl solutions and salt spray tests. This superior anticorrosion property benefits from the self-aligned RGO-ID + nanosheets and the quaternary-N groups present in the RGO-ID + nanocomposite coating. Interestingly, the RGO-ID + also exhibits a high antibacterial activity toward Escherichia coli with 83.4 ± 1.3% antibacterial efficiency, which is attributed to the synergetic effects of RGO-ID + and the electrostatic attraction and hydrogen bonding between RGO-ID + and E. coli. This work offers new opportunities for the successful development of effective corrosion protection and self-antibacterial coatings.

Non-conductive ferromagnetic carbon-coated (Co, Ni) metal/polystyrene nanocomposites films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takacs, H., E-mail: helene.takacs@gmail.com; LTM-CNRS-UJF, CEA, LETI, Minatec Campus, Grenoble 38054; Viala, B.

2016-03-07

This article reports non-conductive ferromagnetic properties of metal/polymer nanocomposite films intended to be used for RF applications. The nanocomposite arrangement is unique showing a core double-shell structure of metal-carbon-polystyrene: M/C//P{sub 1}/P{sub 2}, where M = Co, Ni is the core material, C = graphene or carbon is the first shell acting as a protective layer against oxidation, P{sub 1} = pyrene-terminated polystyrene is the second shell for electrical insulation, and P{sub 2} = polystyrene is a supporting matrix (// indicates actual grafting). The nanocomposite formulation is briefly described, and the film deposition by spin-coating is detailed. Original spin-curves are reported and analyzed. One key outcome is the achievementmore » of uniform and cohesive films at the wafer scale. Structural properties of films are thoroughly detailed, and weight and volume fractions of M/C are considered. Then, a comprehensive overview of DC magnetic and electrical properties is reported. A discussion follows on the magnetic softness of the nanocomposites vs. that of a single particle (theoretical) and the raw powder (experimental). Finally, unprecedented achievement of high magnetization (∼0.6 T) and ultra-high resistivity (∼10{sup 10 }μΩ cm) is shown. High magnetization comes from the preservation of the existing protective shell C, with no significant degradation on the particle net-moment, and high electrical insulation is ensured by adequate grafting of the secondary shell P{sub 1}. To conclude, the metal/polymer nanocomposites are situated in the landscape of soft ferromagnetic materials for RF applications (i.e., inductors and antennas), by means of two phase-diagrams, where they play a crucial role.« less

Finite Element Model Characterization Of Nano-Composite Thermal And Environmental Barrier Coatings

NASA Technical Reports Server (NTRS)

Yamada, Yoshiki; Zhu, Dongming

2011-01-01

Thermal and environmental barrier coatings have been applied for protecting Si based ceramic matrix composite components from high temperature environment in advanced gas turbine engines. It has been found that the delamination and lifetime of T/EBC systems generally depend on the initiation and propagation of surface cracks induced by the axial mechanical load in addition to severe thermal loads. In order to prevent T/EBC systems from surface cracking and subsequent delamination due to mechanical and thermal stresses, T/EBC systems reinforced with nano-composite architectures have showed promise to improve mechanical properties and provide a potential crack shielding mechanism such as crack bridging. In this study, a finite element model (FEM) was established to understand the potential beneficial effects of nano-composites systems such as SiC nanotube-reinforced oxide T/EBC systems.

Nanocomposite tribological coatings with "chameleon" surface adaptation

NASA Astrophysics Data System (ADS)

Voevodin, A. A.; Fitz, T. A.; Hu, J. J.; Zabinski, J. S.

2002-07-01

Nanocomposite tribological coatings were designed to respond to changing environmental conditions by self-adjustment of their surface properties to maintain good tribological performance in any environment. These smart coatings have been dubbed "chameleon" because, analogous to a chameleon changing its skin color to avoid predators, the coating changes its "skin" chemistry and structure to avoid wear. The concept was originally developed using WC, diamondlike carbon, and WS2 material combination for adaptation to a humid/dry environment cycling. In order to address temperature variation, nanocomposite coatings made of yttria-stabilized zirconia (YSZ) in a gold matrix were developed with encapsulated nanosized reservoirs of MoS2 and diamondlike carbon (DLC). Coatings were produced using a combination of laser ablation and magnetron sputtering. They were characterized by x-ray photoelectron spectroscopy, x-ray diffraction, transmission electron microscopy, x-ray energy dispersive spectroscopy, and micro-Raman spectroscopy. Results were correlated with mechanical and tribological characterization. Coating hardness was evaluated using nanoindentation, while coating adhesion and toughness were estimated using scratch and Vickers indentation tests. Friction and wear endurance measurements of YSZ/Au/MoS2/DLC coatings against steel and Si3N4 balls were performed at room temperature in controlled humidity air, dry nitrogen, and vacuum environments, as well as at 500 degC in air. Depending on the environment, coating friction surface changed its chemistry and structure between (i) graphitic carbon for sliding in humid air [coating friction coefficients (c.o.f. 0.10-0.15)], (ii) hexagonal MoS2 for sliding in dry N2 and vacuum (c.o.f. 0.02-0.05), and (iii) metallic Au for sliding in air at 500 degC (c.o.f. 0.10-0.20). The unique coating skin adaptation realized with YSZ/Au/MoS2/DLC and WC/DLC/WS composites proves a universal applicability of the chameleon design concept

In-situ fabrication of zirconium-titanium nano-composite and its coating on Ti-6Al-4V for biomedical applications.

PubMed

Chellappa, Manickam; Vijayalakshmi, Uthirapathy

2017-02-01

In this study, nanocomposite powder consisting of zirconia and titania (Zr-Ti) have been synthesised by sol-gel method, with the aim of protecting Ti-6Al-4V surface. A simple and low cost electrophoretic deposition (EPD) technique has been employed for coating the nanocomposite material on Ti-6Al-4V. The prepared nanocomposite powder was characterised for its functional groups, phase purity, surface topography by Fourier transform infrared spectroscopy, powder X-ray diffraction and scanning electron microscopy. Further, the biocompatibility nature of the composite powder was studied by [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] colorimetric assay and fluorescence analysis with MG63 osteoblast cell lines. The electrochemical behaviour of composite coating was investigated by potentiodynamic polarization and electrochemical impedance method. The results obtained from the electrochemical techniques indicate more corrosion resistance behaviour with increase of R ct value with the corresponding decrease in R dl values. From the above findings, the composite coating acts as a barrier layer against corrosion by preventing the leaching of metal ions from a dense and defect free coating. A scratch test analyser was used to assess the integrity of the coating; the lower traction force value of composite coating with increase in load has confirmed the presence of thick adherent layer on the substrate.

Chitosan-zinc oxide nanocomposite coatings for the prevention of marine biofouling.

PubMed

Al-Naamani, Laila; Dobretsov, Sergey; Dutta, Joydeep; Burgess, J Grant

2017-02-01

Marine biofouling is a worldwide problem affecting maritime industries. Global concerns about the high toxicity of antifouling paints have highlighted the need to develop less toxic antifouling coatings. Chitosan is a natural polymer with antimicrobial, antifungal and antialgal properties that is obtained from partial deacetylation of crustacean waste. In the present study, nanocomposite chitosan-zinc oxide (chitosan-ZnO) nanoparticle hybrid coatings were developed and their antifouling activity was tested. Chitosan-ZnO nanoparticle coatings showed anti-diatom activity against Navicula sp. and antibacterial activity against the marine bacterium Pseudoalteromonas nigrifaciens. Additional antifouling properties of the coatings were investigated in a mesocosm study using tanks containing natural sea water under controlled laboratory conditions. Each week for four weeks, biofilm was removed and analysed by flow cytometry to estimate total bacterial densities on the coated substrates. Chitosan-ZnO hybrid coatings led to better inhibition of bacterial growth in comparison to chitosan coatings alone, as determined by flow cytometry. This study demonstrates the antifouling potential of chitosan-ZnO nanocomposite hybrid coatings, which can be used for the prevention of biofouling. Copyright © 2016 Elsevier Ltd. All rights reserved.

Breakdown of the Coulomb friction law in TiC/a-C:H nanocomposite coatings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pei, Y. T.; Huizenga, P.; Galvan, D.

2006-12-01

Advanced TiC/a-C:H nanocomposite coatings have been produced via reactive deposition in a closed-field unbalanced magnetron sputtering system (Hauzer HTC-1000 or HTC 1200). In this paper, we report on the tribological behavior of TiC/a-C:H nanocomposite coatings in which ultralow friction is tailored with superior wear resistance, two properties often difficult to achieve simultaneously. Tribotests have been performed at room temperature with a ball-on-disk configuration. In situ monitoring of the wear depth of the coated disk together with the wear height of the ball counterpart at nanometer scale reveals that the self-lubricating effects are induced by the formation of transfer films onmore » the surface of the ball counterpart. A remarkable finding is a breakdown of the Coulomb friction law in the TiC/a-C:H nanocomposite coatings. In addition, the coefficient of friction of TiC/a-C:H nanocomposite coatings decreases with decreasing relative humidity. A superior wear resistance of the coated disk at a level of 10{sup -17} m{sup 3}/N m (per lap) has been achieved under the condition of superlow friction and high toughness, both of which require fine TiC nanoparticles (e.g., 2 nm) and a wide matrix separation that must be comparable to the dimensions of the nanoparticles.« less

Calcium-doped ceria/titanate tabular functional nanocomposite by layer-by-layer coating method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Xiang W., E-mail: lxwluck@gmail.co; Devaraju, M.K.; Yin, Shu

2010-07-15

Ca-doped ceria (CDC)/tabular titanate (K{sub 0.8}Li{sub 0.27}Ti{sub 1.73}O{sub 4}, TT) UV-shielding functional nanocomposite with fairly uniform CDC coating layers was prepared through a polyelectrolyte-associated layer-by-layer (LbL) coating method. TT with lepidocrocite-like layered structure was used as the substrate, poly (diallyldimethylammonium chloride) (PDDA) was used as a coupling agent, CDC nanoparticles were used as the main UV-shielding component. CDC/TT nanocomposites with various coating layers of CDC were obtained through a multistep coating process. The phases were studied by X-ray diffraction. The morphology and coating quality were studied by scanning electron microscopy and element mapping of energy dispersive X-ray analysis. The oxidationmore » catalytic activity, UV-shielding ability and using comfort were characterized by Rancimat test, UV-vis spectra and dynamic friction test, respectively. CDC/TT nanocomposites with low oxidation catalytic activity, high UV-shielding ability and good using comfort were finally obtained. - Graphical abstract: Through the control of surface charge of particles calcium-doped ceria/titanate composites with low oxidation catalytic activity, higher UV-shielding ability and excellent comfort was obtained by a facile layer-by-layer coating method.« less

Structure and properties of epoxy-siloxane-silica nanocomposite coatings for corrosion protection.

PubMed

Torrico, Ruben F A O; Harb, Samarah V; Trentin, Andressa; Uvida, Mayara C; Pulcinelli, Sandra H; Santilli, Celso V; Hammer, Peter

2018-03-01

The fraction of the silica/siloxane phase is a crucial parameter, which determines the structure and thus the properties of epoxy-siloxane-silica hybrid coatings. A careful adjustment of the colloidal precursor formulation allows tuning the nanostructure towards a highly condensed and cross-linked hybrid nanocomposite, suitable as an efficient anticorrosive coating. Novel epoxy-siloxane-silica hybrids have been prepared through the curing reaction of poly(bisphenol A-co-epichlorohydrin) (DGEBA) with diethyltriamine (DETA) and (3-glycidoxypropyl)methyltriethoxysilane (GPTMS), followed by hydrolytic condensation of tetraethoxysilane (TEOS) and GPTMS. At a constant proportion of the organic phase, the effects of the varying molar proportions of siloxane (GPTMS) and silica (TEOS) on the film properties have been investigated. A detailed structural analysis suggests for intermediate TEOS to GPTMS ratios a structure of highly condensed silica-siloxane domains covalently bonded to the embedding epoxy phase. The homogeneous distribution of the quasi-spherical sub-nonmetric silica-siloxane nodes is in agreement with low surface roughness (<5 nm), observed by atomic force microscopy. This dense nanostructure results in high thermal stability (>300 °C), strong adhesion to steel substrate and excellent barrier property in saline solution, with corrosion resistance in the GΩ cm 2 range. Copyright © 2017 Elsevier Inc. All rights reserved.

Phase composition and tribomechanical properties of Ti-B-C nanocomposite coatings prepared by magnetron sputtering

NASA Astrophysics Data System (ADS)

Sánchez-López, J. C.; Abad, M. D.; Justo, A.; Gago, R.; Endrino, J. L.; García-Luis, A.; Brizuela, M.

2012-09-01

Protective nanocomposite coatings based on hard ceramic phases (TiC, TiB2) combined with amorphous carbon (a-C) are of interest because of their adequate balance between mechanical and tribological performances. In this work, Ti-B-C nanocomposite coatings were prepared by co-sputtering of graphite and TiB2 targets. Varying the discharge power ratio applied to the graphite and TiB2 targets from 0 to 2, the a-C content in the coatings could be tuned from 0 to 60%, as observed by means of Raman and x-ray photoelectron spectroscopy (XPS). The microstructural characterization demonstrated a progressive decrease in crystallinity from an initial nanocrystalline (nc) TiB2-like structure to a distorted TiBxCy ternary compound with increasing C concentration. X-ray absorption near-edge structure measurements on the B K-edge helped to determine a hexagonal arrangement around the B atoms in the ternary TiBxCy phase. A fitting analysis of the C 1s XPS peak allowed us to evaluate the relative amount of a-C and TiBxCy components. A drastic change in hardness (from 52 to 13 GPa) and friction coefficient values (from 0.8 to 0.2) is noticed when moving from nc-TiB2 to TiBC/a-C nanocomposites. The fraction of a-C necessary to decrease the friction below 0.2 was found to be 45%. Raman observation of the wear tracks determined the presence of disordered sp2-bonded carbon phase associated with the diminution of the friction level.

Hybrid nanocomposite coatings from metal (Mg alloy)-drug deposited onto medical implant by laser adaptive ablation deposition technique

NASA Astrophysics Data System (ADS)

Serbezov, Valery; Sotirov, Sotir; Serbezov, Svetlin

2013-03-01

Drug-eluting medical implants are active implants whose function is to create healing effects. The current requirements for active medical coatings for Drug-eluting medical implants are to be biocompatible, biodegradable, polymer free, mechanically stable and enable a controlled release of one or more drugs and defined degradation. This brings hybrid nanocomposite coatings into focus especially in the field of cardiovascular implants. We studied the properties of Metal (Mg alloy)-Paclitaxel coatings obtained by novel Laser Adaptive Ablation Deposition Technique (LAAD) onto cardiovascular stents from 316 LVM stainless steel material. The morphology and topology of coatings were studied by Bright field / Fluorescence optical microscope and Scanning Electron Microscope (SEM). Comparative measurements were made of the morphology and topology of hybrid, polymer free nanocomposite coatings deposited by LAAD and polymerdrug coatings deposited by classical spray technique. The coatings obtained by LAAD are homogeneous without damages and cracks. Metal nanoparticles with sizes from 40 nm to 230 nm were obtained in drug matrixes. Energy Dispersive X-ray Spectroscopy (EDX) was used for identification of metal nanoparticles presence in hybrid nanocomposites coatings. The new technology opens up possibilities to obtain new hybrid nanocomposite coatings with applications in medicine, pharmacy and biochemistry.

Microstructure and properties of Cu-Sn-Zn-TiO 2 nano-composite coatings on mild steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Weidong; Cao, Di; Jin, Yunxue

Cu-Sn-Zn coatings have been widely used in industry for their unique properties, such as good conductivity, high corrosion resistance and excellent solderability. To further improve the mechanical performance of Cu-Sn-Zn coatings, powder-enhanced method was applied and Cu-Sn-Zn-TiO 2 nano-composite coatings with different TiO 2 concentration were fabricated. The microstructure of Cu-Sn-Zn-TiO 2 nano-composite coatings were investigated by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The mechanical properties of coatings including microhardness and wear resistance were studied. The results indicate that the incorporation of TiO 2 nanoparticle can significantly influence the properties of Cu-Sn-Zn coatings. The microhardness of Cu-Sn-Zn coatingmore » was increased to 383 HV from 330 HV with 1 g/L TiO 2 addition. Also, the corrosion resistance of coating was enhanced. The effects of TiO 2 nanoparticle concentration on the microstructure, mechanical properties and corrosion resistance of Cu-Sn-Zn-TiO 2 nano-composite coatings were discussed.« less

Microstructure and properties of Cu-Sn-Zn-TiO 2 nano-composite coatings on mild steel

DOE PAGES

Gao, Weidong; Cao, Di; Jin, Yunxue; ...

2018-04-18

Cu-Sn-Zn coatings have been widely used in industry for their unique properties, such as good conductivity, high corrosion resistance and excellent solderability. To further improve the mechanical performance of Cu-Sn-Zn coatings, powder-enhanced method was applied and Cu-Sn-Zn-TiO 2 nano-composite coatings with different TiO 2 concentration were fabricated. The microstructure of Cu-Sn-Zn-TiO 2 nano-composite coatings were investigated by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The mechanical properties of coatings including microhardness and wear resistance were studied. The results indicate that the incorporation of TiO 2 nanoparticle can significantly influence the properties of Cu-Sn-Zn coatings. The microhardness of Cu-Sn-Zn coatingmore » was increased to 383 HV from 330 HV with 1 g/L TiO 2 addition. Also, the corrosion resistance of coating was enhanced. The effects of TiO 2 nanoparticle concentration on the microstructure, mechanical properties and corrosion resistance of Cu-Sn-Zn-TiO 2 nano-composite coatings were discussed.« less

Antimicrobial and biocorrosion-resistant MoO3-SiO2 nanocomposite coating prepared by double cathode glow discharge technique

NASA Astrophysics Data System (ADS)

Xu, Jiang; Sun, Teng Teng; Jiang, Shuyun; Munroe, Paul; Xie, Zong-Han

2018-07-01

In this investigation, a MoO3-SiO2 nanocomposite coating was developed on a 316L stainless steel (SS) substrate by double-cathode glow discharge deposition. Chemical valence states, phase composition and microstructure features of the nanocomposite coating were studied using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the nanocomposite coating was composed of a mixture of crystalline MoO3 and amorphous phases, in which amorphous SiO2 phase was embedded between the hexagonal-structured MoO3 grains with an average grain size of ∼8.4 nm. Nanoindentation and scratch tests, together with SEM and TEM observation of locally deformed regions, indicated that the nanocomposite coating exhibited high load-bearing capacity due to a combination of high hardness and good adhesion. Contact angle measurements suggested that the nanocomposite coating was more hydrophobic than uncoated 316L SS. The anti-bacterial activity of the MoO3-SiO2 nanocomposite coating against two bacterial strains (E. coli and S. aureus) was determined by the spread plate method. This showed that both bacterial strains exposed to the coating suffered a significant loss of viability. The influences of sulfate-reducing bacteria (SRB) on the electrochemical behavior of the MoO3-SiO2 nanocomposite coating in modified Postgate's C seawater (PCS) medium were investigated through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The electrochemical tests revealed that the coating had a greater resistance to microbiologically influenced corrosion induced by SRB than uncoated 316L SS. This was corroborated by electrochemical testing (potentiodynamic polarization and EIS), in conjunction with SEM observations of the corroded surfaces.

Electrochemical Impedance Spectroscopy and Corrosion Behavior of Co/CeO2 Nanocomposite Coatings in Simulating Body Fluid Solution

NASA Astrophysics Data System (ADS)

Benea, Lidia

2013-02-01

A series of Co/CeO2 (25 nm) nanocomposite coating materials by electrodeposition were successfully prepared containing different cerium oxide composition in the cobalt-plating bath. Stainless steel (304L) was used as support material for nanocomposite coatings. The nano-CeO2 is uniformly incorporated into cobalt matrix, and the effect on surface morphologies was identified by scanning electron microscopy with energy-dispersive X-ray analysis. Codeposition of nano-CeO2 particles with cobalt disturbs the regular surface morphology of the cobalt coatings. It should be noted that the as-prepared Co/CeO2 nanocomposite coatings were found to be much superior in corrosion resistance over those of pure cobalt coatings materials based on a series of electrochemical impedance spectroscopy measurements in simulating body fluid solution. With increase in the nano-CeO2 particles concentration in the cobalt electrolyte, it is observed that the corrosion resistance of Co/CeO2 increases. Co/CeO2 nanocomposite coatings have higher polarization resistance as compared with pure cobalt layers in simulating body fluid solution.

Size dependent nonlinear optical properties of spin coated zinc oxide-polystyrene nanocomposite films

NASA Astrophysics Data System (ADS)

Jeeju, Pullarkat P.; Jayalekshmi, S.; Chandrasekharan, K.; Sudheesh, P.

2012-11-01

Using simple wet chemical method at room temperature, zinc oxide (ZnO) nanoparticles embedded in polystyrene (PS) matrix were synthesized. The size of the ZnO nanoparticles could be varied by varying the precursor concentration, reaction time and stirring speed. Transparent films of ZnO/PS nanocomposites of thickness around 1 μm were coated on ultrasonically cleaned glass substrates by spin coating. The optical absorptive nonlinearity in ZnO/PS nanocomposite films was investigated using open aperture Z-scan technique with nanosecond laser pulses at 532 nm. The results indicate optical limiting type nonlinearity in the films due to two-photon absorption in ZnO. These films also show a self-defocusing type negative nonlinear refraction in closed aperture Z-scan experiment. The observed nonlinear absorption is strongly dependent on particle size and the normalized transmittance could be reduced to as low as 0.43 by the suitable choice of the ZnO nanoparticle size. These composite films can hence be used as efficient optical limiters for sensor protection. The much-pronounced nonlinear response of these composite films, compared to pure ZnO, combined with the improved stability of ZnO nanoparticles in the PS matrix offer prospects of application of these composite films in the fabrication of stable non-linear optical devices.

Functional Carbon Nanocomposite, Optoelectronic, and Catalytic Coatings

NASA Astrophysics Data System (ADS)

Liang, Yu Teng

Over the past couple decades, fundamental research into carbon nanomaterials has produced a steady stream of groundbreaking physical science. Their record setting mechanical strength, chemical stability, and optoelectronic performance have fueled many optimistic claims regarding the breadth and pace of carbon nanotube and graphene integration. However, present synthetic, processing, and economic constraints have precluded these materials from many practical device applications. To overcome these limitations, novel synthetic techniques, processing methodologies, device geometries, and mechanistic insight were developed in this dissertation. The resulting advancements in material production and composite device performance have brought carbon nanomaterials ever closer to commercial implementation. For improved materials processing, vacuum co-deposition was first demonstrated as viable technique for forming carbon nanocomposite films without property distorting covalent modifications. Co-deposited nanoparticle, carbon nanotube, and graphene composite films enabled rapid device prototyping and compositional optimization. Cellulosic polymer stabilizers were then shown to be highly effective carbon nanomaterial dispersants, improving graphene production yields by two orders of magnitude in common organic solvents. By exploiting polarity interactions, iterative solvent exchange was used to further increase carbon nanomaterial dispersion concentrations by an additional order of magnitude, yielding concentrated inks. On top of their low causticity, these cellulosic nanomaterial inks have highly tunable viscosities, excellent film forming capacity, and outstanding thermal stability. These processing characteristics enable the efficient scaling of carbon nanomaterial coatings and device production using existing roll-to-roll fabrication techniques. Utilizing these process improvements, high-performance gas sensing, energy storage, transparent conductor, and photocatalytic

Towards lightweight nanocomposite coatings for corrosion inhibition: Graphene, carbon nanotubes, and nanostructured magnesium as case studies

NASA Astrophysics Data System (ADS)

Dennis, Robert Vincent, III

The field of nanocomposites is a burgeoning area of research due to the interest in the remarkable properties which can be achieved through their use in a variety of applications, including corrosion resistant coatings. Lightweighting is of increasing importance in the world today due to the ever growing push towards energy efficiency and the green movement and in recent years there has been a vast amount of research performed in the area of developing lightweight nanocomposites for corrosion inhibition. Many new composite materials have been developed through the use of newly developed nanomaterials (including carbonaceous and metallic constituents) and their specialized incorporation in the coating matrix materials. We start with a general review on the development of hybrid nanostructured composites for corrosion protection of base metals from a sustainability perspective in Chapter 1. This review demonstrates the ever swelling requirements for a paradigm shift in the way that we protect metals against corrosion due to the costs and environmental concerns that exist with currently used technology. In Chapter 2, we delve into the much required understanding of graphene oxide and reduced graphene oxide through near-edge X-ray absorption fine structure (NEXAFS) spectroscopy measurements to elucidate information about the electronic structure upon incorporation of nitrogen within the structure. For successful integration of the carbonaceous nanomaterials into a composite coating, a full swath of knowledge is necessary. Within this work we have shown that upon chemical defunctionalization of graphene oxide to reduced graphene oxide by means of hydrazine treatment, nitrogen is incorporated into the structure in the form of a pyrazole ring. In Chapter 3, we demonstrate that by way of in situ polymerization, graphene and multiwalled carbon nanotubes can be incorporated within a polymer (polyetherimide, PEI) matrix. Two systems have been developed including graphene and

Effect of the Number of PZT Coatings on the Crystal Structure and Piezoelectric Properties in PZT-CNT Nanocomposites

NASA Astrophysics Data System (ADS)

Kang, Sin Wook; Cho, Sam Yeon; Bu, Sang Don; Han, Jin Kyu; Lee, Gyoung-Ja; Lee, Min-Ku

2018-05-01

In this study, a nanocomposite was successfully fabricated by mixing Pb(Zr,Ti)O3 (PZT) prepared by using the sol-gel method and functionalized multi-walled carbon nanotubes (MWCNTs). During this process, the effect of the change in the molar concentration of PZT on the crystallinity and the piezoelectric properties of the PZT in the nanocomposite was investigated. As the number of PZT coatings was increased from one to three, PZT was confirmed as having completely covered the MWCNT nanocomposite. Also, the tetragonality of PZT in the crystal structure was confirmed to have increased with increasing number of PZT coatings. Such an increase in crystallinity was followed by an increase in the ferroelectricity of the nanocomposite. A nano-generator was fabricated by using the nanocomposite fabricated as described above, and the characteristics of the nanogenerator were confirmed to have been improved with increasing number of coatings.

Laser and radiofrequency-induced hyperthermia treatment via gold-coated magnetic nanocomposites

PubMed Central

Elsherbini, Alsayed AM; Saber, Mahmoud; Aggag, Mohamed; El-Shahawy, Ahmed; Shokier, Hesham AA

2011-01-01

Introduction The current radiofrequency ablation technique requires invasive needle placement. On the other hand, most of the common photothermal therapeutic methods are limited by lack of accuracy of targeting. Gold and magnetic nanoparticles offer the potential to heat tumor tissue selectively at the cellular level by noninvasive interaction with laser and radiofrequency. Methods Gold nanospheres and gold-coated magnetic nanocomposites were used for inducing hyperthermia to treat subcutaneous Ehrlich carcinoma implanted in female mice. Results In mice treated with gold nanospheres, tumors continued to grow but at a slow rate. In contrast, more than 50% of the tumors treated with gold-coated magnetic nanocomposites completely disappeared. Conclusion This simple and noninvasive method shows great promise as a technique for selective magnetic photothermal treatment. PMID:22114479

One-step synthesis of hybrid inorganic-organic nanocomposite coatings by novel laser adaptive ablation deposition technique

NASA Astrophysics Data System (ADS)

Serbezov, Valery; Sotirov, Sotir

2013-03-01

A novel approach for one-step synthesis of hybrid inorganic-organic nanocomposite coatings by new modification of Pulsed Laser Deposition technology called Laser Adaptive Ablation Deposition (LAAD) is presented. Hybrid nanocomposite coatings including Mg- Rapamycin and Mg- Desoximetasone were produced by UV TEA N2 laser under low vacuum (0.1 Pa) and room temperature onto substrates from SS 316L, KCl and NaCl. The laser fluence for Mg alloy was 1, 8 J/cm2 and for Desoximetasone 0,176 J/cm2 and for Rapamycin 0,118 J/cm2 were respectively. The threedimensional two-segmented single target was used to adapt the interaction of focused laser beam with inorganic and organic material. Magnesium alloy nanoparticles with sizes from 50 nm to 250 nm were obtained in organic matrices. The morphology of nanocomposites films were studied by Bright field / Fluorescence optical microscope and Scanning Electron Microscope (SEM). Fourier Transform Infrared (FTIR) spectroscopy measurements were applied in order to study the functional properties of organic component before and after the LAAD process. Energy Dispersive X-ray Spectroscopy (EDX) was used for identification of Mg alloy presence in hybrid nanocomposites coatings. The precise control of process parameters and particularly of the laser fluence adjustment enables transfer on materials with different physical chemical properties and one-step synthesis of complex inorganic- organic nanocomposites coatings.

Protective Coating

NASA Technical Reports Server (NTRS)

1984-01-01

Inorganic Coatings, Inc.'s K-Zinc 531 protective coating is water-based non-toxic, non-flammable and has no organic emissions. High ratio silicate formula bonds to steel, and in 30 minutes, creates a very hard ceramic finish with superior adhesion and abrasion resistance. Improved technology allows application over a minimal commercial sandblast, fast drying in high humidity conditions and compatibility with both solvent and water-based topcoats. Coating is easy to apply and provides long term protection with a single application. Zinc rich coating with water-based potassium silicate binder offers cost advantages in materials, labor hours per application, and fewer applications over a given time span.

Fabrication of FDTS-modified PDMS-ZnO nanocomposite hydrophobic coating with anti-fouling capability for corrosion protection of Q235 steel.

PubMed

Arukalam, Innocent O; Oguzie, Emeka E; Li, Ying

2016-12-15

Perfluorodecyltrichlorosilane-based poly(dimethylsiloxane)-ZnO (FDTS-based PDMS-ZnO) nanocomposite coating with anti-corrosion and anti-fouling capabilities has been prepared using a one-step fabrication technique. XPS analysis and contact angle measurements showed the fluorine content to increase, while the hydrophobicity of the coatings decreased with addition of FDTS. XRD analysis revealed existence of ZnO nanoparticles of dimensions ranging from 11.45 to 93.01nm on the surface of coatings, with the mean particle size decreasing with FDTS addition, and was confirmed by SEM and TEM observations. Interestingly, the anti-corrosion performance and mechanical properties of the coatings increased remarkably on addition of FDTS. Indeed, the observed low adhesion strength, surface energies and the outstanding anti-corrosive properties imply that the obtained coating would be useful in anti-fouling applications. Copyright © 2016 Elsevier Inc. All rights reserved.

Inorganic/organic hybrid nanocomposite coating applications: Formulation, characterization, and evaluation

NASA Astrophysics Data System (ADS)

Eyassu, Tsehaye

Nanotechnology applications in coatings have shown significant growth in recent years. Systematic incorporation of nano-sized inorganic materials into polymer coating enhances optical, electrical, thermal and mechanical properties significantly. The present dissertation will focus on formulation, characterization and evaluation of inorganic/organic hybrid nanocomposite coatings for heat dissipation, corrosion inhibition and ultraviolet (UV) and near infrared (NIR) cut applications. In addition, the dissertation will cover synthesis, characterization and dispersion of functional inorganic fillers. In the first project, we investigated factors that can affect the "Molecular Fan" cooling performance and efficiency. The investigated factors and conditions include types of nanomaterials, size, loading amount, coating thickness, heat sink substrate, substrate surface modification, and power input. Using the optimal factors, MF coating was formulated and applied on commercial HDUs, and cooling efficiencies up to 22% and 23% were achieved using multi-walled carbon nanotube and graphene fillers. The result suggests that molecular fan action can reduce the size and mass of heat-sink module and thus offer a low cost of LED light unit. In the second project, we report the use of thin organic/inorganic hybrid coating as a protection for corrosion and as a thermal management to dissipate heat from galvanized steel. Here, we employed the in-situ phosphatization method for corrosion inhibition and "Molecular fan" technique to dissipate heat from galvanized steel panels and sheets. Salt fog tests reveal successful completion of 72 hours corrosion protection time frame for samples coated with as low as ~0.7microm thickness. Heat dissipation measurement shows 9% and 13% temperature cooling for GI and GL panels with the same coating thickness of ~0.7microm respectively. The effect of different factors, in-situ phosphatization reagent (ISPR), cross-linkers and nanomaterial on corrosion

Preparation of silver-chitosan nanocomposites and coating on bandage for antibacterial wound dressing application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Susilowati, Endang, E-mail: endwati@yahoo.co.id; Ashadi; Maryani

Bandage is a medical device that is essential for wound dressing. To improve the performance of the bandage, it has been coated by silver-chitosan nanocomposites (Ag/Chit) with pad-dry-cure method. The nanocomposites were performed by chemical reduction method at room temperature using glucose as reducing agent, sodium hydroxide (NaOH) as accelerator reagent, silver nitrate (AgNO{sub 3}) as metal precursor and chitosan as stabilizing agent. Localized surface plasmon resonance (LSPR) absorption band of silver nanoparticles was investigated using UV-Vis spectrophotometer. The bandage coated Ag/Chit nanocomposites (B-Ag/Chit) were characterized by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM).more » In addition, antibacterial activity of the bandage toward Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) were also studied. The formation of silver nanoparticles was confirmed by the appearance of LSPR absorption peak at 412.2 – 423.2 nm. Coating of nanocomposite cause increasing rigidity of bandage and decreasing on crystallinity. The bandages of B-Ag/Chit demonstrated good activity against both Gram positive (S. aureus) and Gram negative (E.Coli). Thus the bandages have a potential to be used for antibacterial wound dressing application.« less

High flux filtration medium based on nanofibrous substrate with hydrophilic nanocomposite coating.

PubMed

Wang, Xuefen; Chen, Xuming; Yoon, Kyunghwan; Fang, Dufei; Hsiao, Benjamin S; Chu, Benjamin

2005-10-01

A novel high flux filtration medium, consisting of a three-tier composite structure, i.e., a nonporous hydrophilic nanocomposite coating top layer, an electrospun nanofibrous substrate midlayer, and a conventional nonwoven microfibrous support, was demonstrated for oil/water emulsion separations for the first time. The nanofibrous substrate was prepared by electrospinning of poly(vinyl alcohol) (PVA) followed by chemical cross-linking with glutaraldehyde (GA) in acetone. The resulting cross-linked PVA substrates showed excellent water resistance and good mechanical properties. The top coating was based on a nanocomposite layer containing hydrophilic polyether-b-polyamide copolymer or a cross-linked PVA hydrogel incorporated with surface-oxidized multiwalled carbon nanotubes (MWNTs). Scanning electron microscopy (SEM) examinations indicated that the nanocomposite layer was nonporous within the instrumental resolution and MWNTs were well dispersed in the polymer matrix. Oil/ water emulsion tests showed that this unique type of filtration media exhibited a high flux rate (up to 330 L/m2-h at the feed pressure of 100 psi) and an excellent total organic solute rejection rate (99.8%) without appreciable fouling. The increase in the concentration of surface-oxidized MWNT in the coating layer generally improves the flux rate, which can be attributed to the generation of more effective hydrophilic nanochannels for water passage in the composite membranes.

Synthesis and characterization of polyaniline coated gold nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zuber, Siti Nurzulaiha Mohd; Kamarun, Dzaraini; Zaki, Hamizah

2015-08-28

Considerable attention has been drawn during the last two decades to prepare nanocomposites consists of conducting polymer and noble metal due to their potential ability to generate a new class of material with novel optical, chemical, electronic or mechanical properties for various applications. In this work, an attempt has been made to synthesize nanocomposite of polyaniline (PANI) coated with gold nanoparticles (AuNPs) chemically with various types of surfactants such as polyvinylpyrrolidone (PVP), and sodium dodecyl sulphate (SDS) which act as stabilizing agents to help in stabilization of the PANI/Gold nanocomposites system. The synthesized nanocomposites were characterized by UV-Visible, field emissionmore » scanning electron microscope (FESEM) and particle size analyzer (PSA). The formation of finger like structure can be seen in the FESEM images when the AuNPs were incorporated into the polymer matrix. The EDX data showed that 18.66% and 12.67% of AuNPs atoms were present in the composite system thus proved the incorporation of AuNPs into the polymer matrix. A small red shift of the absorption peak in the UV-Vis of both PANI/AuNPs composites system may be due to the incorporation of AuNPs in the PANI matrix.« less

Hard and flexible nanocomposite coatings using nanoclay-filled hyperbranched polymers.

PubMed

Fogelström, Linda; Malmström, Eva; Johansson, Mats; Hult, Anders

2010-06-01

The combination of hardness, scratch resistance, and flexibility is a highly desired feature in many coating applications. The aim of this study is to achieve this through the introduction of an unmodified nanoclay, montmorillonite (Na(+)MMT), in a polymer resin based on the hyperbranched polyester Boltorn H30. Smooth and transparent films were prepared from both the neat and the nanoparticle-filled hyperbranched resins. X-ray diffraction (XRD) and transmission electron microscopy (TEM) corroborated a mainly exfoliated structure in the nanocomposite films, which was also supported by results from dynamic mechanical analysis (DMA). Furthermore, DMA measurements showed a 9-16 degrees C increase in Tg and a higher storage modulus-above and below the T(g)-both indications of a more cross-linked network, for the clay-containing film. Thermogravimetric analysis (TGA) demonstrated the influence of the nanofiller on the thermal properties of the nanocomposites, where a shift upward of the decomposition temperature in oxygen atmosphere is attributed to the improved barrier properties of the nanoparticle-filled materials. Conventional coating characterization methods demonstrated an increase in the surface hardness, scratch resistance and flexibility, with the introduction of clay, and all coatings exhibited excellent chemical resistance and adhesion.

Nanocomposites for electromagnetic radiation protection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petrunin, V. F., E-mail: VFPetrunin@mephi.ru

Specific features that characterize nanoparticles and which are due to their small size and allow one to enhance the interaction between the electromagnetic radiation and nanostructured materials and to develop the effective protection of man and equipment against harmful uncontrolled radiation are reported. Examples of the development of nanocomposite radar absorbing materials that can be used for protection of man and equipment are presented.

Electrophoretic co-deposition of cellulose nanocrystals-45S5 bioactive glass nanocomposite coatings on stainless steel

NASA Astrophysics Data System (ADS)

Chen, Qiang; Yang, Yuyun; Pérez de Larraya, Uxua; Garmendia, Nere; Virtanen, Sannakaisa; Boccaccini, Aldo R.

2016-01-01

An organic-inorganic nanocomposite coating consisting of fibrous cellulose nanocrystals and 45S5 bioactive glass, intended as a bioactive surface for bone implants, was developed by a one-step electrophoretic deposition. The composition, surface roughness and wettability of the deposited coatings, influenced by the concentration of each component in the suspension, were controllable as a result of the simplicity of the coating technique. Bioactive glass particles were individually wrapped with porous cellulose layers, forming a porous coating with uniform thickness. Bioactivity test in simulated body fluid revealed a rapid hydroxyapatite formation on the deposited nanocomposite coating. Furthermore, electrochemical test was carried out to understand the corrosion behavior of the deposited coatings during incubation in simulated body fluid. According to the results of this study, the obtained cellulose-bioactive glass coatings with tunable properties represent a promising approach for biofunctionalization of metallic orthopedic implants.

Visible-light induced anti-bacterial and self-cleaning waterborne polyacrylic coating modified with TiO2/polypyrrole nanocomposite; preparation and characterization

NASA Astrophysics Data System (ADS)

Nosrati, Rahimeh; Olad, Ali; Maryami, Fatemeh

2018-07-01

Nowadays, self-cleaning technology is used in various industries to decreasing the time, energy consumption and costs of surface servicing as well as the increasing of surface durability. Self-cleaning and anti-bacterial coatings can be made by the addition of suitable additives to a polymer matrix with good properties. In the present research, TiO2/polypyrrole nanocomposites were prepared in different TiO2 to polypyrrole weight ratios and used in various percent as an additive in waterborne commercial grade polyacrylic latex. Characterization and evaluation of structural and morphological features of nanocomposites and coatings were performed by FTIR, XRD, UV-Vis and FESEM techniques. By the addition of prepared nanocomposites as an additive to the polyacrylic matrix, the hydrophilic, water resistant, anti-bacterial, and photocatalytic coatings were prepared. The TiO2 to polypyrrole weight ratio of TiO2/polypyrrole nanocomposites and the percent of nanocomposite additive in the polymeric matrix were optimized. According to the results, the coating containing 2% and 3% of TiO2/polypyrrole nanocomposite with TiO2 to polypyrrole weight ratio of 100:10 are proposed as the best coating formulations in the formulations examined in this work, due to their good properties in the most of experiments.

Protective coating for ceramic materials

NASA Technical Reports Server (NTRS)

Kourtides, Demetrius A. (Inventor); Churchward, Rex A. (Inventor); Lowe, David M. (Inventor)

1994-01-01

A protective coating for ceramic materials such as those made of silicon carbide, aluminum oxide, zirconium oxide, aluminoborosilicate and silicon dioxide, and a thermal control structure comprising a ceramic material having coated thereon the protective coating. The protective coating contains, in admixture, silicon dioxide powder, colloidal silicon dioxide, water, and one or more emittance agents selected from silicon tetraboride, silicon hexaboride, silicon carbide, molybdenum disilicide, tungsten disilicide and zirconium diboride. In another aspect, the protective coating is coated on a flexible ceramic fabric which is the outer cover of a composite insulation. In yet another aspect, a metallic foil is bonded to the outer surface of a ceramic fabric outer cover of a composite insulation via the protective coating. A primary application of this invention is as a protective coating for ceramic materials used in a heat shield for space vehicles subjected to very high aero-convective heating environments.

Chitosan-Iron Oxide Coated Graphene Oxide Nanocomposite Hydrogel: A Robust and Soft Antimicrobial Biofilm.

PubMed

Konwar, Achyut; Kalita, Sanjeeb; Kotoky, Jibon; Chowdhury, Devasish

2016-08-17

We report a robust biofilm with antimicrobial properties fabricated from chitosan-iron oxide coated graphene oxide nanocomposite hydrogel. For the first time, the coprecipitation method was used for the successful synthesis of iron oxide coated graphene oxide (GIO) nanomaterial. After this, films were fabricated by the gel-casting technique aided by the self-healing ability of the chitosan hydrogel network system. Both the nanomaterial and the nanocomposite films were characterized by techniques such as scanning electron microscopy, FT-IR spectroscopy, X-ray diffraction, and vibrating sample magnetometry. Measurements of the thermodynamic stability and mechanical properties of the films indictaed a significant improvement in their thermal and mechanical properties. Moreover, the stress-strain profile indicated the tough nature of the nanocomposite hydrogel films. These improvements, therefore, indicated an effective interaction and good compatibility of the GIO nanomaterial with the chitosan hydrogel matrix. In addition, it was also possible to fabricate films with tunable surface properties such as hydrophobicity simply by varying the loading percentage of GIO nanomaterial in the hydrogel matrix. Fascinatingly, the chitosan-iron oxide coated graphene oxide nanocomposite hydrogel films displayed significant antimicrobial activities against both Gram-positive and Gram-negative bacterial strains, such as methicillin-resistant Staphylococcus aureus, Staphylococcus aureus, and Escherichia coli, and also against the opportunistic dermatophyte Candida albicans. The antimicrobial activities of the films were tested by agar diffusion assay and antimicrobial testing based on direct contact. A comparison of the antimicrobial activity of the chitosan-GIO nanocomposite hydrogel films with those of individual chitosan-graphene oxide and chitosan-iron oxide nanocomposite films demonstrated a higher antimicrobial activity for the former in both types of tests. In vitro hemolysis

Graphene Oxide-Copper Nanocomposite-Coated Porous CaP Scaffold for Vascularized Bone Regeneration via Activation of Hif-1α.

PubMed

Zhang, Wenjie; Chang, Qing; Xu, Ling; Li, Guanglong; Yang, Guangzheng; Ding, Xun; Wang, Xiansong; Cui, Daxiang; Jiang, Xinquan

2016-06-01

Graphene has been studied for its in vitro osteoinductive capacity. However, the in vivo bone repair effects of graphene-based scaffolds remain unknown. The aqueous soluble graphene oxide-copper nanocomposites (GO-Cu) are fabricated, which are used to coat porous calcium phosphate (CaP) scaffolds for vascularized bone regeneration. The GO-Cu nanocomposites, containing crystallized CuO/Cu2 O nanoparticles of ≈30 nm diameters, distribute uniformly on the surfaces of the porous scaffolds and maintain a long-term release of Cu ions. In vitro, the GO-Cu coating enhances the adhesion and osteogenic differentiation of rat bone marrow stem cells (BMSCs). It is also found that by activating the Erk1/2 signaling pathway, the GO-Cu nanocomposites upregulate the expression of Hif-1α in BMSCs, resulting in the secretion of VEGF and BMP-2 proteins. When transplanted into rat with critical-sized calvarial defects, the GO-Cu-coated calcium phosphate cement (CPC) scaffolds (CPC/GO-Cu) significantly promote angiogenesis and osteogenesis. Moreover, it is observed via histological sections that the GO-Cu nanocomposites are phagocytosed by multinucleated giant cells. The results suggest that GO-Cu nanocomposite coatings can be utilized as an attractive strategy for vascularized bone regeneration. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanocomposites coated with xyloglucan for drug delivery: In vitro studies.

PubMed

Ribeiro, C; Arizaga, G G C; Wypych, F; Sierakowski, M-R

2009-02-09

Enalaprilate (Enal), an active pharmaceutical component, was intercalated into a layered double hydroxide (Mg/Al-LDH) by an ion exchange reaction. The use of a layered double hydroxide (LDH) to release active drugs is limited by the low pH of the stomach (pH approximately 1.2), in whose condition it is readily dissolved. To overcome this limitation, xyloglucan (XG) extracted from Hymenaea courbaril (jatobá) seeds, Brazilian species, was used to protect the LDH and allow the drug to pass through the gastrointestinal tract. All the materials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, elemental analyses, transmission electronic microscopy, thermal analyses, and a kinetic study of the in vitro release was monitored by ultraviolet spectroscopy. The resulting hybrid system containing HDL-Enal-XG(3) slowly released the Enal. In an 8-h of test, the system protected 40% (w/v) of the drug. The kinetic profile showed that the drug release was a co-effect behavior, involving dissolution of inorganic material and ion exchange between the intercalated anions in the lamella and those of phosphate in the buffer solution. The nanocomposite coated protection with XG was therefore efficient in obtaining a slow release of Enal.

Inorganic-organic nanocomposites for optical coatings

NASA Astrophysics Data System (ADS)

Schmidt, Helmut K.; Krug, Herbert; Sepeur-Zeitz, Bernhard; Geiter, Elisabeth

1997-10-01

The fabrication of nanoparticles by the sol-gel process and their use in polymeric or sol-gel-derived inorganic-organic composite matrices opens up interesting possibilities for designing new optical materials. Two different routes have been chosen for preparing optical nanocomposites: The first is the so-called 'in situ route,' where the nanoparticles are synthesized in a liquid mixture from Zr-alkoxides in a polymerizable system and diffractive gratings were produced by embossing uncured film. The second is the 'separate' preparation route, where a sterically stabilized dry nanoboehmite powder was completely redispersed in an epoxy group-containing matrix and hard coatings with optical quality on polycarbonate were prepared.

Transparent Pullulan/Mica Nanocomposite Coatings with Outstanding Oxygen Barrier Properties

PubMed Central

Boyacı, Derya; Trabattoni, Silvia; Tavazzi, Silvia

2017-01-01

This study presents a new bionanocomposite coating on poly(ethylene terephthalate) (PET) made of pullulan and synthetic mica. Mica nanolayers have a very high aspect ratio (α), at levels much greater than that of conventional exfoliated clay layers (e.g., montmorillonite). A very small amount of mica (0.02 wt %, which is ϕ ≈ 0.00008) in pullulan coatings dramatically improved the oxygen barrier performance of the nanocomposite films under dry conditions, however, this performance was partly lost as the environmental relative humidity (RH) increased. This outcome was explained in terms of the perturbation of the spatial ordering of mica sheets within the main pullulan phase, because of RH fluctuations. This was confirmed by modelling of the experimental oxygen transmission rate (OTR) data according to Cussler’s model. The presence of the synthetic nanobuilding block (NBB) led to a decrease in both static and kinetic coefficients of friction, compared with neat PET (≈12% and 23%, respectively) and PET coated with unloaded pullulan (≈26% reduction in both coefficients). In spite of the presence of the filler, all of the coating formulations did not significantly impair the overall optical properties of the final material, which exhibited haze values below 3% and transmittance above 85%. The only exception to this was represented by the formulation with the highest loading of mica (1.5 wt %, which is ϕ ≈ 0.01). These findings revealed, for the first time, the potential of the NBB mica to produce nanocomposite coatings in combination with biopolymers for the generation of new functional features, such as transparent high oxygen barrier materials. PMID:28925951

A self-cleaning coating based on commercial grade polyacrylic latex modified by TiO2/Ag-exchanged-zeolite-A nanocomposite

NASA Astrophysics Data System (ADS)

Nosrati, Rahimeh; Olad, Ali; Nofouzi, Katayoon

2015-08-01

The commercial grade polyacrylic latex was modified in order to prepare a self-cleaning coating. TiO2/Ag-exchanged-zeolite-A nanocomposite was prepared and used as additive in the matrix of polyacrylic latex to achieve a hydrophilic and photocatalytic coating. FTIR and UV-visible spectroscopy, X-ray diffraction patterns and FESEM were used to characterize the composition and structure of the nanocomposites and coatings. The acrylic coatings, were prepared by using of TiO2/Ag-exchanged-zeolite-A additive, had better UV and visible light absorption, hydrophilic, degradation of organic pollutants, stability in water and antimicrobial properties than pristine commercial grade polyacrylic latex coating. According to the results, the modified polyacrylic based coating containing 0.5 wt% of TiO2/Ag-exchanged-zeolite-A nanocomposite additive with TiO2 to Ag-exchanged-zeolite-A ratio of 1:2 was the best coating considering most of useful properties such as small band gap and low water contact angle. The water contact angle for unmodified polyacrylic latex coating was 68° which was decreased to less than 10° in modified coating after 24 h LED lamp illumination.

Microstructure, Mechanical Properties, and Two-Body Abrasive Wear Behavior of Cold-Sprayed 20 vol.% Cubic BN-NiCrAl Nanocomposite Coating

NASA Astrophysics Data System (ADS)

Luo, Xiao-Tao; Yang, Er-Juan; Shang, Fu-Lin; Yang, Guan-Jun; Li, Chen-Xin; Li, Chang-Jiu

2014-10-01

20 vol.% cubic boron nitride (cBN) dispersoid reinforced NiCrAl matrix nanocomposite coating was prepared by cold spray using mechanically alloyed nanostructured composite powders. The as-sprayed nanocomposite coating was annealed at a temperature of 750 °C to enhance the inter-particle bonding. Microstructure of spray powders and coatings was characterized. Vickers microhardness of the coatings was measured. Two-body abrasive wear behavior of the coatings was examined on a pin-on-disk test. It was found that, in mechanically alloyed composite powders, nano-sized and submicro-sized cBN particles are uniformly distributed in nanocrystalline NiCrAl matrix. Dense coating was deposited by cold spray at a gas temperature of 650 °C with the same phases and grain size as those of the starting powder. Vickers hardness test yielded a hardness of 1063 HV for the as-sprayed 20 vol.% cBN-NiCrAl coating. After annealed at 750 °C for 5 h, unbonded inter-particle boundaries were partially healed and evident grain growth of nanocrystalline NiCrAl was avoided. Wear resistance of the as-sprayed 20 vol.% cBN-NiCrAl nanocomposite coating was comparable to the HVOF-sprayed WC-12Co coating. Annealing of the nanocomposite coating resulted in the improvement of wear resistance by a factor of ~33% owing to the enhanced inter-particle bonding. Main material removal mechanisms during the abrasive wear are also discussed.

Incorporation of Fe3O4/CNTs nanocomposite in an epoxy coating for corrosion protection of carbon steel

NASA Astrophysics Data System (ADS)

Pham, Gia Vu; Truc Trinh, Anh; To, Thi Xuan Hang; Duong Nguyen, Thuy; Trang Nguyen, Thu; Hoan Nguyen, Xuan

2014-09-01

In this study Fe3O4/CNTs composite with magnetic property was prepared by attaching magnetic nanoparticles (Fe3O4) to carbon nanotubes (CNTs) by hydrothermal method. The obtained Fe3O4/CNTs composite was characterized by Fourier transform infrared (FTIR) spectroscopy, powder x-ray diffraction and transmission electron microscopy. The Fe3O4/CNTs composite was then incorporated into an epoxy coating at concentration of 3 wt%. Corrosion protection of epoxy coating containing Fe3O4/CNTs composite was evaluated by electrochemical impedance spectroscopy and adhesion measurement. The impedance measurements show that Fe3O4/CNTs composite enhanced the corrosion protection of epoxy coating. The corrosion resistance of the carbon steel coated by epoxy coating containing Fe3O4/CNTs composite was significantly higher than that of carbon steel coated by clear epoxy coating and epoxy coating containing CNTs. FE-SEM photographs of fracture surface of coatings showed good dispersion of Fe3O4/CNTs composite in the epoxy matrix.

Corrosion Behavior and Microhardness of Ni-P-SiO2-Al2O3 Nano-composite Coatings on Magnesium Alloy

NASA Astrophysics Data System (ADS)

Sadreddini, S.; Rahemi Ardakani, S.; Rassaee, H.

2017-05-01

In the present work, nano-composites of Ni-P-SiO2-Al2O3 were coated on AZ91HP magnesium alloy. The surface morphology of the nano-composite coating was studied by field emission scanning electron microscopy (FESEM). The amount of SiO2 in the coating was determined by energy-dispersive analysis of x-ray (EDX), and the crystalline structure of the coating was examined by x-ray diffractometer (XRD). All the experiments concerning the corrosion behavior of the coating carried out in 3.5 wt.% NaCl solution and evaluated by electrochemical impedance spectroscopy (EIS) and polarization technique. The results showed that an incorporation of SiO2 and Al2O3 in Ni-P coating at the SiO2 concentration of 10 g/Land 14 g/LAl2O3 led to the lowest corrosion rate ( i corr = 1.3 µA/cm2), the most positive E corr and maximum microhardness (496 VH). Furthermore, Ni-P-SiO2-Al2O3 nano-composite coating possesses less porosity than that in Ni-P coating, resulting in improving corrosion resistance.

Potentiodynamic studies of Ni-P-TiO2 nano-composited coating on the mild steel deposited by electroless plating method

NASA Astrophysics Data System (ADS)

Uttam, Vibha; Duchaniya, R. K.

2016-05-01

Now a days, corrosion studies are important for reducing the wastage of metals. The importance of corrosion studies is two folds i.e. first is economic, including the reduction of material losses resulting from the wasting away or sudden failure of materials and second is conservation Electroless process is an autocatalytic reduction method in which metallic ions are reduced in the solution. Nanocomposite coatings of Ni-P-TiO2 on mild steel are deposited by varying volume of TiO2 nano-powder by electroless method from Ni-P plating bath containing Nickel Sulphate as a source of nickel ions, sodium hypophosphite as the reducing agent, lactic acid as a complexing agents and TiO2 nano powder. Electroless Ni-P-TiO2 coating have been widely used in the chemical process industries, mechanical industries, electronic industries and chloroalkali industries due to their excellent corrosion with mechanical properties. In the present work, deposition of Ni-P alloy coating and Ni-P-TiO2 nanocomposited coatings were done on the mild steel and corrosion properties were studied with Potentio-dynamic polarization measurements method in 3.5 wt% sodium chloride solution. It showed in the experiments that Ni-P-TiO2 nanocomposited coating has better corrosion resistance as comparedthan Ni-P alloy coating. Morphological studies were done by field emission scanning electron microscopy (FESEM), energy-dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD). These studies confirmed the deposition of Ni-P alloy coating and Ni-P-TiO2 nanocomposited coating.

A superhydrophobic EP/PDMS nanocomposite coating with high gamma radiation stability

NASA Astrophysics Data System (ADS)

Zhang, Yan; Ren, Fule; Liu, Yujian

2018-04-01

The superhydrophobic coatings with high gamma radiation stability were prepared by using epoxy/polydimethylsiloxane (EP/PDMS) resins as the matrix and silica nanoparticles as the fillers. The nanocomposite coatings exhibit superhydrophobicity with a high water contact angle (WCA) of 154° and a low sliding angle of 7°. With the amount of SiO2 increasing from 0 to 30%, the surface shows the hierarchically structure gradually and its roughness raised from 4 nm to 278 nm. And little change in the WCA of the coatings (from 155° to 149°) was observed when the pH of the droplets varied from 2 to 14. In addition, the coatings also show good adhesion grade (5B), high hardness (6H) and outstanding stability for high dose gamma radiation.

Electrophoretic-deposited novel ternary silk fibroin/graphene oxide/hydroxyapatite nanocomposite coatings on titanium substrate for orthopedic applications

NASA Astrophysics Data System (ADS)

Li, Ming; Xiong, Pan; Mo, Maosong; Cheng, Yan; Zheng, Yufeng

2016-09-01

The combination of graphene oxide (GO) with robust mechanical property, silk fibroin (SF) with fascinating biological effects and hydroxyapatite (HA) with superior osteogenic activity is a competitive approach to make novel coatings for orthopedic applications. Herein, the feasibility of depositing ternary SF/GO/HA nanocomposite coatings on Ti substrate was firstly verified by exploiting electrophoretic nanotechnology, with SF being used as both a charging additive and a dispersion agent. The surface morphology, microstructure and composition, in vitro hemocompatibility and in vitro cytocompatibility of the resulting coatings were investigated by SEM, Raman, FTIR spectra and biocompatibility tests. Results demonstrated that GO, HA and SF could be co-deposited with a uniform, smooth thin-film morphology. The hemolysis rate analysis and the platelet adhesion test indicated good blood compatibility of the coatings. The human osteosarcoma MG63 cells displayed well adhesion and proliferation behaviors on the prepared coatings, with enhanced ALP activities. The present study suggested that SF/GO/HA nanocomposite coatings could be a promising candidate for the surface functionalization of biomaterials, especially as orthopedic implant coating.

Smart Nanocomposite Coatings with Chameleon Surface Adaptation in Tribological Applications

NASA Astrophysics Data System (ADS)

Voevodin, A. A.; Zabinski, J. S.

Smart nanocomposite tribological coatings were designed to respond to changing environmental conditions by self-adjustment of their surface properties to maintain good tribological performance in any environment. These coatings have been dubbed "chameleon" because of their ability to change their surface chemistry and structure to avoid wear. The first "chameleon" coatings were made of WC, WS2, and DLC; these coatings provided superior mechanical toughness and performance in dry/humid environmental cycling. In order to address temperature variation, the second generation of "chameleon" coatings were made of yttria stabilized zirconia (YSZ) in a gold matrix with encapsulated nano-sized reservoirs of MoS2 and DLC. High temperature lubrication with low melting point glassy ceramic phases was also explored. All coatings were produced using a combination of laser ablation and magnetron sputtering. They were thoroughly characterized by various analytical, mechanical, and tribological methods. Coating toughness was remarkably enhanced by activation of a grain boundary sliding mechanism. Friction and wear endurance measurements were performed in controlled humidity air, dry nitrogen, and vacuum environments, as well as at 500-600 °C in air. Unique friction and wear performance in environmental cycling was demonstrated.

In situ ZnO-PVA nanocomposite coated microfluidic chips for biosensing

NASA Astrophysics Data System (ADS)

Habouti, Salah; Kunstmann-Olsen, Casper; Hoyland, James D.; Rubahn, Horst-Günter; Es-Souni, Mohammed

2014-05-01

Microfluidic chips with integrated fluid and optical connectors have been generated via a simple PDMS master-mould technique. In situ coating using a Zinc oxide polyvinylalcohol based sol-gel method results in ultrathin nanocomposite layers on the fluid channels, which makes them strongly hydrophilic and minimizes auto contamination of the chips by injected fluorescent biomarkers.

A versatile cooperative template-directed coating method to construct uniform microporous carbon shells for multifunctional core-shell nanocomposites.

PubMed

Guan, Buyuan; Wang, Xue; Xiao, Yu; Liu, Yunling; Huo, Qisheng

2013-03-21

A very simple cooperative template-directed coating method is developed for the preparation of core-shell, hollow, and yolk-shell microporous carbon nanocomposites. Particularly, the cationic surfactant C16TMA(+)·Br(-) used in the coating procedure improves the core dispersion in the reaction media and serves as the soft template for mesostructured resorcinol-formaldehyde resin formation, which results in the uniform polymer and microporous carbon shell coating on most functional cores with different surface properties. The core diameter and the shell thickness of the nanocomposites can be precisely tailored. This approach is highly reproducible and scalable. Several grams of polymer and carbon nanocomposites can be easily prepared by a facile one-pot reaction. The Au@hydrophobic microporous carbon yolk-shell catalyst favors the reduction of more hydrophobic nitrobenzene than hydrophilic 4-nitrophenol by sodium borohydride, which makes this type of catalyst@carbon yolk-shell composites promising nanomaterials as selective catalysts for hydrophobic reactants.

Investigation of the Corrosion Behavior of Poly(Aniline-co-o-Anisidine)/ZnO Nanocomposite Coating on Low-Carbon Steel

NASA Astrophysics Data System (ADS)

Mobin, M.; Alam, R.; Aslam, J.

2016-07-01

A copolymer of aniline (AN) and o-anisidine (OA), Poly(AN-co-OA) and its nanocomposite with ZnO nanoparticles, Poly(AN-co-OA)/ZnO were synthesized by chemical oxidative polymerization using ammonium persulfate as an oxidant in hydrochloric acid medium. The synthesized compounds were characterized using FTIR, XRD, SEM-EDS, TEM, and electrical conductivity techniques. The copolymer and nanocomposite were separately dissolved in N-methyl-2-pyrrolidone and were casted on low-carbon steel specimens using 10% epoxy resin as a binder. The anticorrosive properties of the coatings were studied in different corrosive environments such as 0.1 M HCl, 5% NaCl solution, and distilled water at a temperature of 30 °C by conducting corrosion tests which include immersion test, open circuit potential measurements, potentiodynamic polarization measurements, and atmospheric exposure test. The surface morphology of the coatings prior to and after one-month immersion in corrosive solution was evaluated using SEM. It was observed that the nanocomposite coating exhibited higher corrosion resistance and provided better barrier properties in comparison with copolymer coating. The presence of ZnO nanoparticles improved the anticorrosion properties of copolymer coating in all corrosive media subjected to investigation.

Oleic acid-grafted chitosan/graphene oxide composite coating for corrosion protection of carbon steel.

PubMed

Fayyad, Eman M; Sadasivuni, Kishor Kumar; Ponnamma, Deepalekshmi; Al-Maadeed, Mariam Al Ali

2016-10-20

An anticorrosion coating film based on the formation of nanocomposite coating is reported in this study. The composite consisted of chitosan (green matrix), oleic acid, and graphene oxide (nano filler). The nanocomposite coating was arranged on the surface of carbon steel, and the corrosion resistance was monitored using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP). Compared to the pure chitosan (CS) coating, the corrosion resistance of oleic acid-modified chitosan/graphene oxide film (CS/GO-OA) is increased by 100 folds. Since the well-dispersed smart grafted nanolayers delayed the penetration rate of corrosive species and thus maintained long term anticorrosive stability which is correlated with hydrophobicity and permeability. Copyright © 2016 Elsevier Ltd. All rights reserved.

Potentiodynamic studies of Ni-P-TiO{sub 2} nano-composited coating on the mild steel deposited by electroless plating method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uttam, Vibha, E-mail: vibhauttam74@gmail.com; Duchaniya, R. K., E-mail: rkduchaniya.meta@mnit.ac.in

2016-05-06

Now a days, corrosion studies are important for reducing the wastage of metals. The importance of corrosion studies is two folds i.e. first is economic, including the reduction of material losses resulting from the wasting away or sudden failure of materials and second is conservation Electroless process is an autocatalytic reduction method in which metallic ions are reduced in the solution. Nanocomposite coatings of Ni-P-TiO{sub 2} on mild steel are deposited by varying volume of TiO{sub 2} nano-powder by electroless method from Ni-P plating bath containing Nickel Sulphate as a source of nickel ions, sodium hypophosphite as the reducing agent,more » lactic acid as a complexing agents and TiO{sub 2} nano powder. Electroless Ni-P-TiO{sub 2} coating have been widely used in the chemical process industries, mechanical industries, electronic industries and chloroalkali industries due to their excellent corrosion with mechanical properties. In the present work, deposition of Ni-P alloy coating and Ni-P-TiO{sub 2} nanocomposited coatings were done on the mild steel and corrosion properties were studied with Potentio-dynamic polarization measurements method in 3.5 wt% sodium chloride solution. It showed in the experiments that Ni-P-TiO{sub 2} nanocomposited coating has better corrosion resistance as comparedthan Ni-P alloy coating. Morphological studies were done by field emission scanning electron microscopy (FESEM), energy–dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD). These studies confirmed the deposition of Ni-P alloy coating and Ni-P-TiO{sub 2} nanocomposited coating.« less

Influence of Bi addition on the property of Ag-Bi nano-composite coatings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yuxin; Tay, See Leng; Zhou, Xiaowei

Silver (Ag) coatings have been widely used in many industry areas due to their excellent conductivity. However, wider applications of Ag coatings have been hindered by their poor mechanical properties. In this research, to improve the mechanical performance, Ag-Bi nano-composite coatings were prepared by a novel ionic co-discharge method. A systematic study of the microstructure, mechanical properties, electrical conductivity and antibacterial behavior of the resulting coating was performed. The results indicated that after adding an appropriate amount of Bi containing solution into the Ag plating solution, Ag-Bi nanoparticles were in-situ formed and distributed uniformly throughout the coating matrix, resulting inmore » a significant improvement in the mechanical properties. The hardness of Ag-Bi coating was increased by 60% compared to that of the pure Ag coating. The corrosion resistance of Ag-Bi coatings was also enhanced. The Ag-Bi coatings prepared in the current study will find a broader application in electronics, jewelry, aerospace and other industries.« less

Influence of Bi addition on the property of Ag-Bi nano-composite coatings

DOE PAGES

Wang, Yuxin; Tay, See Leng; Zhou, Xiaowei; ...

2018-03-26

Silver (Ag) coatings have been widely used in many industry areas due to their excellent conductivity. However, wider applications of Ag coatings have been hindered by their poor mechanical properties. In this research, to improve the mechanical performance, Ag-Bi nano-composite coatings were prepared by a novel ionic co-discharge method. A systematic study of the microstructure, mechanical properties, electrical conductivity and antibacterial behavior of the resulting coating was performed. The results indicated that after adding an appropriate amount of Bi containing solution into the Ag plating solution, Ag-Bi nanoparticles were in-situ formed and distributed uniformly throughout the coating matrix, resulting inmore » a significant improvement in the mechanical properties. The hardness of Ag-Bi coating was increased by 60% compared to that of the pure Ag coating. The corrosion resistance of Ag-Bi coatings was also enhanced. The Ag-Bi coatings prepared in the current study will find a broader application in electronics, jewelry, aerospace and other industries.« less

Analyzing and Modelling the Corrosion Behavior of Ni/Al2O3, Ni/SiC, Ni/ZrO2 and Ni/Graphene Nanocomposite Coatings

PubMed Central

Saeed, Adil; Braun, Wolfgang; Bajwa, Rizwan; Rafique, Saqib

2017-01-01

A study has been presented on the effects of intrinsic mechanical parameters, such as surface stress, surface elastic modulus, surface porosity, permeability and grain size on the corrosion failure of nanocomposite coatings. A set of mechano-electrochemical equations was developed by combining the popular Butler–Volmer and Duhem expressions to analyze the direct influence of mechanical parameters on the electrochemical reactions in nanocomposite coatings. Nanocomposite coatings of Ni with Al2O3, SiC, ZrO2 and Graphene nanoparticles were studied as examples. The predictions showed that the corrosion rate of the nanocoatings increased with increasing grain size due to increase in surface stress, surface porosity and permeability of nanocoatings. A detailed experimental study was performed in which the nanocomposite coatings were subjected to an accelerated corrosion testing. The experimental results helped to develop and validate the equations by qualitative comparison between the experimental and predicted results showing good agreement between the two. PMID:29068395

Polydopamine-Coated Manganese Complex/Graphene Nanocomposite for Enhanced Electrocatalytic Activity Towards Oxygen Reduction.

PubMed

Parnell, Charlette M; Chhetri, Bijay; Brandt, Andrew; Watanabe, Fumiya; Nima, Zeid A; Mudalige, Thilak K; Biris, Alexandru S; Ghosh, Anindya

2016-08-16

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 × 10(6) mol(-1)s(-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.

Surface studies on superhydrophobic and oleophobic polydimethylsiloxane-silica nanocomposite coating system

NASA Astrophysics Data System (ADS)

Basu, Bharathibai J.; Dinesh Kumar, V.; Anandan, C.

2012-11-01

Superhydrophobic and oleophobic polydimethylsiloxane (PDMS)-silica nanocomposite double layer coating was fabricated by applying a thin layer of low surface energy fluoroalkyl silane (FAS) as topcoat. The coatings exhibited WCA of 158-160° and stable oleophobic property with oil CA of 79°. The surface morphology was characterized by field emission scanning electron microscopy (FESEM) and surface chemical composition was determined by energy dispersive X-ray spectrometery (EDX) and X-ray photoelectron spectroscopy (XPS). FESEM images of the coatings showed micro-nano binary structure. The improved oleophobicity was attributed to the combined effect of low surface energy of FAS and roughness created by the random distribution of silica aggregates. This is a facile, cost-effective method to obtain superhydrophobic and oleophobic surfaces on larger area of various substrates.

Improvement of food packaging related properties in whey protein isolate‑based nanocomposite films and coatings by addition of montmorillonite nanoplatelets

NASA Astrophysics Data System (ADS)

Schmid, Markus; Merzbacher, Sarah; Brzoska, Nicola; Müller, Kerstin; Jesdinszki, Marius

2017-11-01

In the present study the effects of the addition of montmorillonite (MMT) nanoplatelets on whey protein isolate (WPI)-based nanocomposite films and coatings were investigated. The main objective was the development of WPI-based MMT-nanocomposites with enhanced barrier and mechanical properties. WPI-based nanocomposite cast-films and coatings were prepared by dispersing 0 % (reference sample), 3 %, 6 %, 9 % (w/w protein) MMT, or, depending on the protein concentration, also 12 % and 15 % (w/w protein) MMT into native WPI-based dispersions, followed by subsequent denaturation during the drying and curing process. The natural MMT nanofillers could be randomly dispersed into film-forming WPI-based nanodispersions, displaying good compatibility with the hydrophilic biopolymer matrix. As a result, by addition of 15 % (w/w protein) MMT into 10 % (w/w dispersion) WPI-based cast-films or coatings, the oxygen permeability (OP) was reduced by 91 % for glycerol-plasticized and 84 % for sorbitol-plasticized coatings, water vapor transmission rate (WVTR) was reduced by 58 % for sorbitol-plasticized cast-films. Due to the addition of MMT- nanofillers the Young’s modulus and tensile strength improved by 315 % and 129 %, respectively, whereas elongation at break declined by 77 % for glycerol-plasticized cast-films. In addition, comparison of plasticizer type revealed that sorbitol-plasticized cast-films were generally stiffer and stronger, but less flexible compared glycerol-plasticized cast-films. Viscosity measurements demonstrated good processability and suitability for up-scaled industrial processes of native WPI-based nanocomposite dispersions, even at high nanofiller-loadings. These results suggest that the addition of natural MMT- nanofillers into native WPI-based matrices to form nanocomposite films and coatings holds great potential to replace well-established, fossil-based packaging materials for at least certain applications such as oxygen barriers as part of

Marine fouling release silicone/carbon nanotube nanocomposite coatings: on the importance of the nanotube dispersion state.

PubMed

Beigbeder, Alexandre; Mincheva, Rosica; Pettitt, Michala E; Callow, Maureen E; Callow, James A; Claes, Michael; Dubois, Philippe

2010-05-01

The present work reports on the influence of the dispersion quality of multiwall carbon nanotubes (MWCNTs) in a silicone matrix on the marine fouling-release performance of the resulting nanocomposite coatings. A first set of coatings filled with different nanofiller contents was prepared by the dilution of a silicone/MWCNTs masterbatch within a hydrosilylation-curing polydimethylsiloxane resin. The fouling-release properties of the nanocomposite coatings were studied through laboratory assays with the marine alga (seaweed) Ulva, a common fouling species. As reported previously (see Ref. [19]), the addition of a small (0.05%) amount of carbon nanotubes substantially improves the fouling-release properties of the silicone matrix. This paper shows that this improvement is dependent on the amount of filler, with a maximum obtained with 0.1 wt% of multiwall carbon nanotubes (MWCNTs). The method of dispersion of carbon nanotubes in the silicone matrix is also shown to significantly (p = 0.05) influence the fouling-release properties of the coatings. Dispersing 0.1% MWCNTs using the masterbatch approach yielded coatings with circa 40% improved fouling-release properties over those where MWCNTs were dispersed directly in the polymeric matrix. This improvement is directly related to the state of nanofiller dispersion within the cross-linked silicone coating.

Protective Coatings for Metals

NASA Technical Reports Server (NTRS)

Ruggieri, D. J.; Rowe, A. P.

1986-01-01

Report evaluates protective coatings for metal structures in seashore and acid-cloud environments. Evaluation result of study of coating application characteristics, repair techniques, and field performance. Products from variety of manufacturers included in study. Also factory-coated panels and industrial galvanized panels with and without topcoats.

Chitosan-doped-hybrid/TiO2 nanocomposite based sol-gel coating for the corrosion resistance of aluminum metal in 3.5% NaCl medium.

PubMed

J, Balaji; M G, Sethuraman

2017-11-01

The study outlines the role of chitosan, a biopolymer on corrosion behavior of Hy/nano-TiO 2 based sol-gel coating over aluminum metal. In this study organic-inorganic hybrid sols were synthesized through hydrolysis and condensation of 3-glycidoxypropyltrimethoxy silane (GPTMS), tetraethoxysilane (TEOS) and titanium (IV) isopropoxide (TIP) in acidic solution. Chitosan was doped into sol-gel matrix and self-assembled over aluminum substrate. The resultant chitosan-doped-Hy/nano-TiO 2 sol-gel coating was characterized by Fourier Transform Infrared (FT-IR) spectra, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Energy-Dispersive X-ray Spectroscopy (EDX) analyses. The as-tailored aluminum substrate was evaluated for corrosion resistance in neutral medium. The protection ability of these coatings was evaluated by electrochemical impedance studies (EIS) and potentiodynamic polarization (PP) measurements in 3.5% NaCl medium. The EIS and PP results showed that chitosan-doped- Hy/nano-TiO 2 sol-gel coating exhibited better protection from corrosion than the undoped Hy/TiO 2 nanocomposite coating. Copyright © 2017 Elsevier B.V. All rights reserved.

Investigation of anticorrosion properties of nanocomposites of spray coated zinc oxide and titanium dioxide thin films on stainless steel (304L SS) in saline environment

NASA Astrophysics Data System (ADS)

P, Muhamed Shajudheen V.; S, Saravana Kumar; V, Senthil Kumar; Maheswari A, Uma; M, Sivakumar; Rani K, Anitha

2018-01-01

The present study reports the anticorrosive nature of nanocomposite thin films of zinc oxide and titanium dioxide on steel substrate (304L SS) using spray coating method. The morphology and chemical constituents of the nanocomposite thin film were characterized by field effect scanning electron microscopy and energy dispersive analysis of x-ray (EDAX) studies. From the EDAX studies, it was observed that nanocomposite coatings of desired stoichiometry can be synthesized using present coating technique. The cyclic voltametric techniques such as Tafel analysis and electrochemical impedance spectroscopy (EIS) analysis were conducted to study the anticorrosion properties of the coatings. The E corr values obtained from Tafel polarization curves of the sample coated with nanocomposites of ZnO and TiO2 in different ratios (5:1, 1:1 and 1:5) indicated that the corrosion resistance was improved compared to bare steel. The coating resistance values obtained from the Nyquist plot after fitting with equivalent circuit confirmed the improved anticorrosion performance of the coated samples. The sample coated with ZnO: TiO2 in the ratio 1:5 showed better corrosion resistance compared to other ratios. The Tafel and EIS studies were repeated after exposure to 5% NaCl for 390 h and the results indicated the anticorrosive nature of the coating in the aggressive environment. The root mean square deviation of surface roughness values calculated from the AFM images before and after salt spray indicated the stability of coating in the saline environment.

Formation of Heterogeneous Powder Coatings with a Two-Level Micro-and Nanocomposite Structure under Gas-Dynamic Spraying Conditions

NASA Astrophysics Data System (ADS)

Aborkin, A. V.; Alymov, M. I.; Arkhipov, V. E.; Khrenov, D. S.

2018-02-01

Heterogeneous coatings have been deposited by the cold gas-dynamic spraying of mechanically synthesized AMg2/graphite + Al2O3 powders. A specific feature of the coatings formed is the existence of a two-level micro-and nanocomposite structure. It has been established that an increase in the content of microsized Al2O3 particles in the mixture from 10 to 30 wt % produces a twofold increase in the thickness of the coating deposited for the same time period from 140 to 310 μm. A further growth in the content of microsized Al2O3 particles in the mixture up to 50 wt % leads to a decrease in the thickness of the coating formed to 40 μm. The manufactured coatings have a high microhardness ranging from 1.7 to 3.2 GPa depending on their composition. The high microhardness of these coatings is caused by an increase in the hardness of the matrix material due to the creation of a nanocomposite structure, which strengthens the immobilization of microsized Al2O3 particles in it, thus improving the properties of the heterogeneous coating as a whole.

Sliding Wear and Fretting Wear of DLC-Based, Functionally Graded Nanocomposite Coatings

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Pohlchuck, B.; Street, Kenneth W.; Zabinski, J. S.; Sanders, J. H.; Voevodin, A. a.; Wu, R. L. C.

1999-01-01

Improving the tribological functionality of diamondlike carbon (DLC) films--developing, good wear resistance, low friction, and high load-carrying capacity-was the aim of this investigation. Nanocomposite coatings consisting of an amorphous DLC (a-DLC) top layer and a functionally graded titanium-titanium carbon-diamondlike carbon (Ti-Ti(sub x) C(sub y)-DLC) underlayer were produced on AISI 440C stainless steel substrates by the hybrid technique of magnetron sputtering and pulsed-laser deposition. The resultant DLC films were characterized by Raman spectroscopy, scanning electron microscopy, and surface profilometry. Two types of wear experiment were conducted in this investioation: sliding friction experiments and fretting wear experiments. Unidirectional ball-on-disk sliding friction experiments were conducted to examine the wear behavior of an a-DLC/Ti-Ti(sub x) C(sub y)-DLC-coated AISI 440C stainless steel disk in sliding contact with a 6-mm-diameter AISI 440C stainless steel ball in ultrahigh vacuum, dry nitrogen, and humid air. Although the wear rates for both the coating and ball were low in all three environments, the humid air and dry nitrogen caused mild wear with burnishing, in the a-DLC top layer, and the ultrahigh vacuum caused relatively severe wear with brittle fracture in both the a-DLC top layer and the Ti-Ti(sub x) C(sub y)-DLC underlayer. For reference, amorphous hydrogenated carbon (H-DLC) films produced on a-DLC/Ti-Ti(sub x) C(sub y)-DLC nanocomposite coatings by using an ion beam were also examined in the same manner. The H-DLC films markedly reduced friction even in ultrahigh vacuum without sacrificing wear resistance. The H-DLC films behaved much like the a-DLC/Ti-Ti(sub x) C(sub y)-DLC nanocomposite coating in dry nitrogen and humid air, presenting low friction and low wear. Fretting wear experiments were conducted in humid air (approximately 50% relative humidity) at a frequency of 80 Hz and an amplitude of 75 micron on an a

Corrosion Protection by Calcite-Type Coatings

DTIC Science & Technology

1989-10-01

CORROSION PROTECTION BY CALCITE -TYPE COATINGS OCTOBER, 1989 Prepared by: OCEAN CITY RESEARCH CORPORATION Tennessee Avenue & Beach Thorofare Ocean...REPORT DATE OCT 1989 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Corrosion Protection by Calcite -Type Coatings 5a. CONTRACT... calcite -type coatings to segregated seawater ballast tanks. If perfected, a calcite coating approach could substantially reduce the cost of corrosion

Nanocomposites biodegradable coating on BOPET films to enhance hot seal strength properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbaro, G., E-mail: giovannibarbaro@email.it; Galdi, M. R., E-mail: mrgaldi@unisa.it; Di Maio, L., E-mail: ldimaio@unisa.it

2015-12-17

The coating technology is a strategic solution to improve the properties of flexible packaging films. Indeed, additional functional layers are often designed and added as coating on the substrate, in order to improve the characteristic of the flexible packaging and to meet the requirements for the desired gas or vapour barrier, for adhesion and sealing, or for improving the film printability, its aesthetics and durability. Moreover, this technology allows to functionalize a polymeric substrate applying materials with different chemistry, rheology, thermal and structural characteristics. BOPET films are widely used for food packaging applications thanks to their good gas barrier andmore » mechanical properties, high transparency and for the excellent printability. In regard to sealing performance, BOPET films show poor sealing properties so they are mostly submitted to lamination processes with polyethylene. Nevertheless, this solution compromises the PET recyclability and influences the gas permeability of the multilayer PET based structures. The aim of this work is to investigate on the effect of nanocomposite biodegradable coatings for BOPET substrates in enhancing the heat sealing strength of eco-compatible PET/PLA films. At this regards, different percentages of Cloisite C30B (0%, 2% and 4%{sub wt/wt}) have been added to PLA by solution intercalation technique and the nanocomposite biodegradable materials produced have been applied on BOPET commercial films by casting. The BOPET coated films have been characterized in order to evaluate the heat sealing strength and the mechanical, gas permeability and surface properties. The results have shown that the addition of nanoclay in PLA coating significantly enhance the hot tack properties of the PET/PLA system produced, while the oxygen and water vapour permeability are slightly increased if compared to pure BOPET films.« less

Nanocomposites biodegradable coating on BOPET films to enhance hot seal strength properties

NASA Astrophysics Data System (ADS)

Barbaro, G.; Galdi, M. R.; Di Maio, L.; Incarnato, L.

2015-12-01

The coating technology is a strategic solution to improve the properties of flexible packaging films. Indeed, additional functional layers are often designed and added as coating on the substrate, in order to improve the characteristic of the flexible packaging and to meet the requirements for the desired gas or vapour barrier, for adhesion and sealing, or for improving the film printability, its aesthetics and durability. Moreover, this technology allows to functionalize a polymeric substrate applying materials with different chemistry, rheology, thermal and structural characteristics. BOPET films are widely used for food packaging applications thanks to their good gas barrier and mechanical properties, high transparency and for the excellent printability. In regard to sealing performance, BOPET films show poor sealing properties so they are mostly submitted to lamination processes with polyethylene. Nevertheless, this solution compromises the PET recyclability and influences the gas permeability of the multilayer PET based structures. The aim of this work is to investigate on the effect of nanocomposite biodegradable coatings for BOPET substrates in enhancing the heat sealing strength of eco-compatible PET/PLA films. At this regards, different percentages of Cloisite C30B (0%, 2% and 4%wt/wt) have been added to PLA by solution intercalation technique and the nanocomposite biodegradable materials produced have been applied on BOPET commercial films by casting. The BOPET coated films have been characterized in order to evaluate the heat sealing strength and the mechanical, gas permeability and surface properties. The results have shown that the addition of nanoclay in PLA coating significantly enhance the hot tack properties of the PET/PLA system produced, while the oxygen and water vapour permeability are slightly increased if compared to pure BOPET films.

Electro-codeposition of Ni-SiO2 nanocomposite coatings from deep eutectic solvent with improved corrosion resistance

NASA Astrophysics Data System (ADS)

Li, Ruiqian; Hou, Yuanyuan; Liang, Jun

2016-03-01

Electro-codeposition of nano-sized SiO2 particles into the metal matrix in aqueous solution is generally difficult. In this paper, the nano-sized SiO2 particles were successfully codeposited in the Ni matrix from a choline chloride (ChCl)/ethylene glycol (EG) based deep eutectic solvent (DES) by pulse electro-codeposition. The effects of nano-sized SiO2 particles on electrochemical behaviour of Ni(II) were investigated. The microstructure, composition and corrosion resistance of pure Ni and Ni-SiO2 nanocomposite coatings were explored. Results showed that the SiO2 nanoparticles exhibited excellent dispersion stability in ChCl:2EG DES without any stabilizing additives and the presence of SiO2 nanoparticles have significant effects on the nucleation mechanism of Ni. The maximum content of SiO2 nanoparticles in composite coatings can achieve 4.69 wt.%, which closes to the level of co-deposition micro-sized SiO2 particles from aqueous solution. The Ni-SiO2 nanocomposite coatings exhibit much better corrosion resistance than pure Ni coating, and the corrosion resistance performance increases with increasing SiO2 content in the composite coatings.

The optimization of CNT-PVA nanocomposite for mild steel coating: Effect of CNTs concentration on the corrosion rate of mild steel

NASA Astrophysics Data System (ADS)

Maryam, M.; Ibrahim, N. M. A. A.; Eswar, K. A.; Guliling, M.; Suhaimi, M. H. F.; Khusaimi, Z.; Abdullah, S.; Rusop, M.

2018-05-01

Carbon Nanotubes (CNTs) are molecular-scale tubes of graphitic carbon which have outstanding mechanical and magnetic properties with extraordinary strength. It can be said that CNTs can be used in coating application to prevent corrosion and lower the rate of corrosion on steel. However, CNT alone cannot be used for coating purposes. Therefore, by combining it with polymer to produce a nanocomposite thin film, it can be used for nanocoating on mild steel substrate. Polyvinyl alcohol (PVA) was chosen due to its high strength and high modulus polymer fibers and has the possibilities of improving the physicochemical properties of carbon nanotubes. Carbon nanotubes and polyvinyl alcohol (CNT-PVA) nanocomposite were prepared by using sol-gel method and coated as thin film on mild steel substrate by using spin coating. Sol-gel is a convenient technique used for the production of nanocomposite aqueous solution. Five samples were prepared at the different concentration of CNTs-PVA to verify the corrosion rate application. The samples were then characterized by Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) obtaining the structural properties, surface morphology and topography of samples. Raman spectroscopy was used to determine the microraman spectra of CNTs which showed the quality and purity of samples. Finally, corrosion test was done to measure the corrosion rate of samples at the different concentration of CNTs/PVA nanocomposite.

Tailored synthesis of TiC/a-C nanocomposite tribological coatings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinez-Martinez, D.; Lopez-Cartes, C.; Justo, A.

2005-11-15

Composite coatings made of nanocrystalline TiC (nc-TiC) particles and amorphous carbon (a-C) have been prepared in a double magnetron sputtering system using graphite and titanium targets under Ar bombardment. Chemical composition and microstructure of coatings were studied by transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and x-ray diffraction (XRD) for a set of samples prepared varying the ratio and intensity of power applied to each magnetron. Changes in coatings microstructure, from a quasipolycrystalline TiC to a nanocomposite formed by nanocrystals of TiC embedded in an amorphous matrix of carbon (nc-TiC/a-C), are observed depending on the synthesis conditions. Tribologicalmore » and mechanical properties of coatings were tested using a pin-on-disk tribometer and an ultramicrohardness indenter, respectively. Coatings with moderate hardness (7-27 GPa), low friction (0.1-0.2), and low wear rates (k{approx}10{sup -7} mm{sup 3}/N m) were obtained. A percentage between 15% and 30% of TiC is found as an optimum value to get a good compromise between good mechanical and tribological properties. Finally, a mapping of the mechanical and tribological properties of the nc-TiC/a-C system is presented for the synthesis conditions employed.« less

Further improvement of mechanical and tribological properties of Cr-doped diamond-like carbon nanocomposite coatings by N codoping

NASA Astrophysics Data System (ADS)

Zou, Changwei; Xie, Wei; Tang, Xiaoshan

2016-11-01

In this study, the effects of nitrogen codoping on the microstructure and mechanical properties of Cr-doped diamond-like carbon (DLC) nanocomposite coatings were investigated in detail. Compared with undoped DLC coatings, the Cr-DLC and N/Cr-DLC coatings showed higher root-mean-square (RMS) roughness values. However, from the X-ray photoelectron spectroscopy (XPS) and Raman results, the fraction of sp2 carbon bonds of N/Cr-DLC coatings increased with increasing N content, which indicated the graphitization of the coatings. The hardness and elastic modulus of N/Cr-DLC coatings with 1.8 at. % N were about 26.8 and 218 GPa, respectively. The observed hardness increase with N codoping was attributed to the incorporation of N in the C network along with the formation of CrC(N) nanoparticles, as confirmed from the transmission electron microscopy (TEM) results. The internal stress markedly decreased from 0.93 to 0.32 GPa as the N content increased from 0 to 10.3 at. %. Furthermore, N doping significantly improved the high-temperature dry friction behavior of DLC coatings. The friction coefficient of N/Cr-DLC coatings with 8.0 and 10.3 at. % N was kept at about 0.2 during the overall sliding test at 500 °C. These results showed that appropriate N doping could promote the mechanical and tribological properties of Cr-DLC nanocomposite coatings.

Protective Coatings

NASA Technical Reports Server (NTRS)

1980-01-01

General Magnaplate Corporation's pharmaceutical machine is used in the industry for high speed pressing of pills and capsules. Machine is automatic system for molding glycerine suppositories. These machines are typical of many types of drug production and packaging equipment whose metal parts are treated with space spinoff coatings that promote general machine efficiency and contribute to compliance with stringent federal sanitation codes for pharmaceutical manufacture. Collectively known as "synergistic" coatings, these dry lubricants are bonded to a variety of metals to form an extremely hard slippery surface with long lasting self lubrication. The coatings offer multiple advantages; they cannot chip, peel or be rubbed off. They protect machine parts from corrosion and wear longer, lowering maintenance cost and reduce undesired heat caused by power-robbing friction.

Carbon Coated Boron Nitride Nanosheets for Polymer Nanocomposites with Enhanced Dielectric Performance

PubMed Central

Yang, Minhao; Zhao, Hang; He, Delong; Hu, Chaohe; Chen, Haowei; Bai, Jinbo

2017-01-01

Carbon coated boron nitride nanosheets (BNNSs@C) hybrids with different carbon contents were synthesized by a chemical vapor deposition (CVD) method. The content of carbon in as-obtained BNNSs@C hybrids could be precisely adjusted from 2.50% to 22.62% by controlling the carbon deposition time during the CVD procedure. Afterward, the BNNSs@C hybrids were subsequently incorporated into the polyvinylidene fluoride (PVDF) matrix to fabricate the BNNSs@C/PVDF nanocomposites through a combination of solution and melting blending methods. The dielectric properties of the as-obtained BNNSs@C/PVDF nanocomposites could be accurately tuned by adjusting the carbon content. The resultant nanocomposites could afford a high dielectric constant about 39 (103 Hz) at BNNSs@C hybrids loading of 30 vol %, which is 4.8 times larger than that of pristine BNNSs-filled ones at the same filler loading, and 3.5 times higher than that of pure PVDF matrix. The largely enhanced dielectric performance could be ascribed to the improved interfacial polarizations of BNNSs/carbon and carbon/PVDF interfaces. The approach reported here offers an effective and alternative method to fabricate high-performance dielectric nanocomposites, which could be potentially applied to the embedded capacitors with high dielectric performance. PMID:28773105

Thin film heater for removable volatile protecting coatings.

PubMed

Karim, Abid

2013-01-01

Freshly coated aluminum mirrors have excellent reflectivity at far ultraviolet wavelengths. However, reflectivity rapidly degrades when the mirror surfaces are exposed to atmosphere. In order to avoid this problem, freshly coated aluminum surface can be protected by over-coating of a removable volatile protecting coating. This protecting coating can be re-evaporated by controlled heating or by some other methods when required. This type of removable coating has immediate application in UV space astronomy. The purpose of this paper is to demonstrate the feasibility of re-evaporation of removable volatile Zn protecting coating using a NiCr thin film heater without affecting the reflection properties of Al mirror surfaces.

Long-term aging of Ag/a-C:H:O nanocomposite coatings in air and in aqueous environment

NASA Astrophysics Data System (ADS)

Drábik, Martin; Pešička, Josef; Biederman, Hynek; Hegemann, Dirk

2015-04-01

Nanocomposite coatings of silver particles embedded in a plasma polymer matrix possess interesting properties depending on their microstructure. The film microstructure is affected among others also by the RF power supplied during the deposition, as shown by transmission electron microscopy. The optical properties are characterized by UV-vis-NIR spectroscopy. An anomalous optical absorption peak from the Ag nanoparticles is observed and related to the microstructure of the nanocomposite films. Furthermore, a long-term aging of the coatings is studied in-depth in ambient air and in aqueous environments. It is shown that the studied films are not entirely stable. The deposition conditions and the microstructure of the films affect the processes taking place during their aging in both environments.

Method of coating metal surfaces to form protective metal coating thereon

DOEpatents

Krikorian, Oscar H.; Curtis, Paul G.

1992-01-01

A process is disclosed for forming a protective metal coating on a metal surface using a flux consisting of an alkali metal fluoride, an alkaline earth metal fluoride, an alkali metal fluoaluminate, an alkali metal fluosilicate, and mixtures thereof. The flux, in particulate form, is mixed with particles of a metal coating material which may comprise aluminum, chromium, mixtures thereof, and alloys containing at least 50 wt. % aluminum and the particulate mixture is applied to the metal surface in a single step, followed by heating the coated metal surface to a temperature sufficient to cause the metal coating material to react with the metal surface to form a protective reaction product in the form of a metal coating bonded to the metal surface. The metal surface which reacts with the metal coating material to form the protective coating may comprise Fe, Co, Ni, Ti, V, Cr, Mn, Zr, Nb, Mo, Tc, Hf, Ta, W, Re and alloys thereof.

Method of coating metal surfaces to form protective metal coating thereon

DOEpatents

Krikorian, O.H.; Curtis, P.G.

1992-03-31

A process is disclosed for forming a protective metal coating on a metal surface using a flux consisting of an alkali metal fluoride, an alkaline earth metal fluoride, an alkali metal fluoaluminate, an alkali metal fluosilicate, and mixtures thereof. The flux, in particulate form, is mixed with particles of a metal coating material which may comprise aluminum, chromium, mixtures thereof, and alloys containing at least 50 wt. % aluminum and the particulate mixture is applied to the metal surface in a single step, followed by heating the coated metal surface to a temperature sufficient to cause the metal coating material to react with the metal surface to form a protective reaction product in the form of a metal coating bonded to the metal surface. The metal surface which reacts with the metal coating material to form the protective coating may comprise Fe, Co, Ni, Ti, V, Cr, Mn, Zr, Nb, Mo, Tc, Hf, Ta, W, Re and alloys thereof. 1 figure.

Synthesis of cuprous oxide epoxy nanocomposite as an environmentally antimicrobial coating.

PubMed

M El Saeed, Ashraf; Abd El-Fattah, M; Azzam, Ahmed M; Dardir, M M; Bader, Magd M

2016-08-01

Cuprous oxide is commonly used as a pigment; paint manufacturers begin to employ cuprous oxide as booster biocides in their formulations, to replace the banned organotins as the principal antifouling compounds. Epoxy coating was reinforced with cuprous oxide nanoparticles (Cu2O NPs). The antibacterial as well as antifungal activity of Cu2O epoxy nanocomposite (Cu2O EN) coating films was investigated. Cu2O NPs were also experimented for antibiofilm and time-kill assay. The thermal stability and the mechanical properties of Cu2O EN coating films were also investigated. The antimicrobial activity results showed slowdown, the growth of organisms on the Cu2O EN coating surface. TGA results showed that incorporating Cu2O NPs into epoxy coating considerably enhanced the thermal stability and increased the char residue. The addition of Cu2O NPs at lower concentration into epoxy coating also led to an improvement in the mechanical resistance such as scratch and abrasion. Cu2O NPs purity was confirmed by XRD. The TEM photograph demonstrated that the synthesized Cu2O NPs were of cubic shape and the average diameter of the crystals was around 25nm. The resulting perfect dispersion of Cu2O NPs in epoxy coating revealed by SEM ensured white particles embedded in the epoxy matrix. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigation of the nanostructure and wear properties of physical vapor deposited CrCuN nanocomposite coatings

NASA Astrophysics Data System (ADS)

Baker, M. A.; Kench, P. J.; Tsotsos, C.; Gibson, P. N.; Leyland, A.; Matthews, A.

2005-05-01

This article presents results on CrCuN nanocomposite coatings grown by physical vapor deposition. The immiscibility of Cr (containing a supersaturation of nitrogen) and Cu offers the potential of depositing a predominantly metallic (and therefore tough) nanocomposite, composed of small Cr(N) metallic and/or β-Cr2N ceramic grains interdispersed in a (minority) Cu matrix. A range of CrCuN compositions have been deposited using a hot-filament enhanced unbalanced magnetron sputtering system. The stoichiometry and nanostructure have been studied by x-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, and x-ray diffraction. Hardness, wear resistance, and impact resistance have been determined by nanoindentation, reciprocating-sliding, and ball-on-plate high-cycle impact. Evolution of the nanostructure as a function of composition and correlations of the nanostructure and mechanical properties of the CrCuN coatings are discussed. A nanostructure comprised of 1-3 nm α-Cr(N) and β-Cr2N grains separated by intergranular regions of Cu gives rise to a coating with significantly enhanced resistance to impact wear.

Liquid Galvanic Coatings for Protection of Imbedded Metals

NASA Technical Reports Server (NTRS)

MacDowell, Louis G. (Inventor); Curran, Joseph J. (Inventor)

2003-01-01

Coating compositions and methods of their use are described herein for the reduction of corrosion in imbedded metal structures. The coatings are applied as liquids to an external surface of a substrate in which the metal structures are imbedded. The coatings are subsequently allowed to dry. The liquid applied coatings provide galvanic protection to the imbedded metal structures. Continued protection can be maintained with periodic reapplication of the coating compositions, as necessary, to maintain electrical continuity. Because the coatings may be applied using methods similar to standard paints, and because the coatings are applied to external surfaces of the substrates in which the metal structures are imbedded, the corresponding corrosion protection may be easily maintained. The coating compositions are particularly useful in the protection of metal-reinforced concrete.

Dense protective coatings, methods for their preparation and coated articles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tulyani, Sonia; Bhatia, Tania; Smeggil, John G.

A method for depositing a protective coating on a complex shaped substrate includes the steps of: (1) dipping a complex shaped substrate into a slurry to form a base coat thereon, the slurry comprising an aqueous solution, at least one refractory metal oxide, and at least one transient fluid additive present in an amount of about 0.1 percent to 10 percent by weight of the slurry; (2) curing the dipped substrate; (3) dipping the substrate into a precursor solution to form a top barrier coat thereon; and (4) heat treating the dipped, cured substrate to form a protective coating.

Unique visible-light-assisted field emission of tetrapod-shaped ZnO/reduced graphene-oxide core/coating nanocomposites

PubMed Central

Wu, Chaoxing; Kim, Tae Whan; Guo, Tailiang; Li, Fushan

2016-01-01

The electronic and the optoelectronic properties of graphene-based nanocomposites are controllable, making them promising for applications in diverse electronic devices. In this work, tetrapod-shaped zinc oxide (T-ZnO)/reduced graphene oxide (rGO) core/coating nanocomposites were synthesized by using a hydrothermal-assisted self-assemble method, and their optical, photoelectric, and field-emission properties were investigated. The ZnO, an ideal ultraviolet-light-sensitive semiconductor, was observed to have high sensitivity to visible light due to the rGO coating, and the mechanism of that sensitivity was investigated. We demonstrated for the first time that the field-emission properties of the T-ZnO/rGO core/coating nanocomposites could be dramatically enhanced under visible light by decreasing the turn-on field from 1.54 to 1.41 V/μm and by increasing the current density from 5 to 12 mA/cm2 at an electric field of 3.5 V/μm. The visible-light excitation induces an electron jump from oxygen vacancies on the surface of ZnO to the rGO layer, resulting in a decrease in the work function of the rGO and an increase in the emission current. Furthermore, a field-emission light-emitting diode with a self-enhanced effect was fabricated making full use of the photo-assisted field-emission process. PMID:27941822

Protective coatings for sensitive materials

DOEpatents

Egert, Charles M.

1997-01-01

An enhanced protective coating to prevent interaction between constituents of the environment and devices that can be damaged by those constituents. This coating is provided by applying a synergistic combination of diffusion barrier and physical barrier materials. These materials can be, for example, in the form of a plurality of layers of a diffusion barrier and a physical barrier, with these barrier layers being alternated. Further protection in certain instances is provided by including at least one layer of a getter material to actually react with one or more of the deleterious constituents. The coating is illustrated by using alternating layers of an organic coating (such as Parylene-C.TM.) as the diffusion barrier, and a metal coating (such as aluminum) as the physical barrier. For best results there needs to be more than one of at least one of the constituent layers.

Deposition and characterization of TiAlSiN nanocomposite coatings prepared by reactive pulsed direct current unbalanced magnetron sputtering

NASA Astrophysics Data System (ADS)

Barshilia, Harish C.; Ghosh, Moumita; Shashidhara; Ramakrishna, Raja; Rajam, K. S.

2010-08-01

This work reports the performance of high speed steel drill bits coated with TiAlSiN nanocomposite coating at different Si contents (5.5-8.1 at.%) prepared using a four-cathode reactive pulsed direct current unbalanced magnetron sputtering system. The surface morphology of the as-deposited coatings was characterized using field emission scanning electron microscopy. The crystallographic structure, chemical composition and bonding structure were evaluated using X-ray diffraction, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, respectively. The corrosion behavior, mechanical properties and thermal stability of TiAlSiN nanocomposite coatings were also studied using potentiodynamic polarization, nanoindentation and Raman spectroscopy, respectively. The TiAlSiN coating thickness was approximately 2.5-2.9 μm. These coatings exhibited a maximum hardness of 38 GPa at a silicon content of approximately 6.9 at.% and were stable in air up to 850 °C. For the performance evaluation, the TiAlSiN coated drills were tested under accelerated machining conditions by drilling a 12 mm thick 304 stainless steel plate. Under dry conditions the uncoated drill bits failed after drilling 50 holes, whereas, TiAlSiN coated drill bits (Si = 5.5 at.%) drilled 714 holes before failure. Results indicated that for TiAlSiN coated drill bits the tool life increased by a factor of more than 14.

Preparation of UV-protective kefiran/nano-ZnO nanocomposites: physical and mechanical properties.

PubMed

Shahabi-Ghahfarrokhi, Iman; Khodaiyan, Faramarz; Mousavi, Mohammad; Yousefi, Hossein

2015-01-01

In this study, we investigated the effect of ZnO nanoparticles (ZN) as a UV-protective agent of kefiran biopolymers. Our results showed that with increasing ZN content, the tensile strength, elongation at break, and tensile energy to break the kefiran film and nanocomposites also increased. Kefiran nanocomposites with a ZN content higher than 2% produced a UV-protective film with good visual properties, low sensibility to water, and low water-vapor permeability. The thermal properties of all specimens, analyzed by DSC, showed that the ZN content had a negative effect on Tg and a positive effect on nanocomposites' melting point. TEM, SEM micrography and XRD spectrum analysis confirmed the hypothesis that ZNs act like a ball bearing, making movement of kefiran chains easier and increasing elongation at break, while simultaneously decreasing the Tg of kefiran nanocomposites. Copyright © 2014 Elsevier B.V. All rights reserved.

Electrodeposition and Characterization of Ni-Al2O3 Nanocomposite Coatings on Steel

NASA Astrophysics Data System (ADS)

Akhtar, Khalida; Khan, Zia Ullah; Gul, Muhammad; Zubair, Naila; Shah, Syed Sajjad Ali

2018-05-01

Monodispersed alumina particles were synthesized by the homogeneous precipitation under reflux boiling. The particles were employed as reinforcement additives in the electrodeposited Ni-Al2O3 composite coatings on steel. The deposited pure Ni and Ni-Al2O3 composite coatings were analyzed by SEM, XRD, and microhardness tester. The wear resistance and friction coefficient of the coated samples were determined by using a ball-on-disk tribometer. Furthermore, XRD analysis showed that coating temperature and the presence of particles in the deposited coatings had a noticeable effect on the preferred orientation of the crystalline faces of the nickel grains. Significant differences were noted in the texture coefficient of the pure Ni and Ni-Al2O3 composite coatings produced at different temperatures. These differences were attributed to the changes in the microstructure of the matrix caused by the embedded Al2O3 particles. Results revealed that wear resistance and the friction coefficient were turned out to be higher and smaller, respectively, for the composite coatings as compared to pure Ni coating at a given sliding distance. It was noted that the corrosion resistance of these specimens increased in the following order: bare substrate < pure Ni coating < Ni-Al2O3 nanocomposite coatings.

Electromagnetic properties of absorber fabric coated with BaFe12O19/MWCNTs/PANi nanocomposite in X and Ku bands frequency

NASA Astrophysics Data System (ADS)

Afzali, Arezoo; Mottaghitalab, Vahid; Seyyed Afghahi, Seyyed Salman; Jafarian, Mojtaba; Atassi, Yomen

2017-11-01

Current investigation focuses on the electromagnetic properties of nonwoven fabric coated with BaFe12O19 (BHF) /MWCNTs/PANi nanocomposite in X and Ku bands. The BHF/MWCNTs and BHF/MWCNTs/PANi nanocomposites are prepared using the sol gel and in-situ polymerization methods respectively. The absorbent fabric was prepared based on applying a 40 wt% of BHF/MWCNTs/PANi nanocomposite in silicon resin on nonwoven fabric via roller coating technique The X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and vector network analysis (VNA) are used to peruse microstructural, magnetic and electromagnetic features of the composite and absorber fabric respectively. The microscopic images of the fabric coated with magnetic nanocomposite shows a homogenous layer of nanoparticles on the fabric surface. The maximum reflection loss of binary nano-composite BHF/MWCNTs was measured about -28.50 dB at 11.72 GHz with 1.7 GHz bandwidth (RL < -10 dB) in X band. Moreover in Ku band, the maximum reflection loss is -29.66 dB at 15.78 GHz with 3.2 GHz bandwidths. Also the ternary nanocomposite BHF/MWCNTs/PANi exhibits a broad band absorber over a wide range of X band with a maximum reflection loss of -36.2 dB at 10.2 GHz with 1.5 GHz bandwidth and in the Ku band has arrived a maximum reflection loss of -37.65 dB at 12.84 GHz with 2.43 GHz bandwidth. This result reflects the synergistic effect of the different components with different loss mechanisms. As it is observed due to the presence of PANi in the structure of nanocomposite, the amount of absorption has increased extraordinarily. The absorber fabric exhibits a maximum reflection loss of -24.2 dB at 11.6 GHz with 4 GHz bandwidth in X band. However, in Ku band, the absorber fabric has had the maximum absorption in 16.88 GHz that is about -24.34 dB with 6 GHz bandwidth. Therefore, results indicate that the fabric samples coated represents appreciable maximum absorption value of more than 99% in

A Comparative Study on the Effect of MWCNT as Reinforcement on the Corrosion Parameters of Different Ni-W/MWCNTs Nanocomposite Coatings in Various Corrosive Media

NASA Astrophysics Data System (ADS)

Mohammadpour, Zahra; Zare, Hamid R.

2018-07-01

Nickel-tungsten multi-walled carbon nanotubes (Ni-W/MWCNTs) nanocomposite coatings were co-electrodeposited in the ammonium-free bath by means of constant direct current coulometry. The results indicate that the amount of MWCNTs incorporated into the nanocomposite coatings has a key role in the improvement of their microhardness and corrosion resistance. The corrosion behavior of the coatings was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy methods in three corrosive media of 3.5 wt% NaCl, 1.0 M NaOH, and 0.5 M H2SO4. The experimental data of the corrosion current density (jcorr), corrosion rate (CR), the polarization resistance (Rp), and microhardness indicate that the presence of MWCNTs in coatings improves the quality of those coatings. The surface morphology of the coatings and the elemental analysis data were obtained by scanning electron microscopy and energy dispersive X-ray microanalysis respectively. As the results showed, the coatings were uniform and crack-free in the presence of 5.3 wt% carbon. Also, a microhardness test revealed that the nanocomposite coating containing 5.3 wt% carbon obtained in an ammonium-free bath which provided the higher content of tungsten had the highest hardness value among others.

A Comparative Study on the Effect of MWCNT as Reinforcement on the Corrosion Parameters of Different Ni-W/MWCNTs Nanocomposite Coatings in Various Corrosive Media

NASA Astrophysics Data System (ADS)

Mohammadpour, Zahra; Zare, Hamid R.

2018-03-01

Nickel-tungsten multi-walled carbon nanotubes (Ni-W/MWCNTs) nanocomposite coatings were co-electrodeposited in the ammonium-free bath by means of constant direct current coulometry. The results indicate that the amount of MWCNTs incorporated into the nanocomposite coatings has a key role in the improvement of their microhardness and corrosion resistance. The corrosion behavior of the coatings was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy methods in three corrosive media of 3.5 wt% NaCl, 1.0 M NaOH, and 0.5 M H2SO4. The experimental data of the corrosion current density (jcorr), corrosion rate (CR), the polarization resistance (Rp), and microhardness indicate that the presence of MWCNTs in coatings improves the quality of those coatings. The surface morphology of the coatings and the elemental analysis data were obtained by scanning electron microscopy and energy dispersive X-ray microanalysis respectively. As the results showed, the coatings were uniform and crack-free in the presence of 5.3 wt% carbon. Also, a microhardness test revealed that the nanocomposite coating containing 5.3 wt% carbon obtained in an ammonium-free bath which provided the higher content of tungsten had the highest hardness value among others.

A pre-protective strategy for precise tumor targeting and efficient photodynamic therapy with a switchable DNA/upconversion nanocomposite.

PubMed

Yu, Zhengze; Ge, Yegang; Sun, Qiaoqiao; Pan, Wei; Wan, Xiuyan; Li, Na; Tang, Bo

2018-04-14

Tumor-specific targeting based on folic acid (FA) is one of the most common and significant approaches in cancer therapy. However, the expression of folate receptors (FRs) in normal tissues will lead to unexpected targeting and unsatisfactory therapeutic effect. To address this issue, we develop a pre-protective strategy for precise tumor targeting and efficient photodynamic therapy (PDT) using a switchable DNA/upconversion nanocomposite, which can be triggered in the acidic tumor microenvironment. The DNA/upconversion nanocomposite is composed of polyacrylic acid (PAA) coated upconversion nanoparticles (UCNPs), the surface of which is modified using FA and chlorin e6 (Ce6) functionalized DNA sequences with different lengths. Initially, FA on the shorter DNA was protected by a longer DNA to prevent the bonding to FRs on normal cells. Once reaching the acidic tumor microenvironment, C base-rich longer DNA forms a C-quadruplex, resulting in the exposure of the FA groups and the bonding of FA and FRs on cancer cell membranes to achieve precise targeting. Simultaneously, the photosensitizer chlorin e6 (Ce6) gets close to the surface of UCNPs, enabling the excitation of Ce6 to generate singlet oxygen ( 1 O 2 ) under near infrared light via Förster resonance energy transfer (FRET). In vivo experiments indicated that higher tumor targeting efficiency was achieved and the tumor growth was greatly inhibited through the pre-protective strategy.

Electrophoretic deposition and electrochemical behavior of novel graphene oxide-hyaluronic acid-hydroxyapatite nanocomposite coatings

NASA Astrophysics Data System (ADS)

Li, Ming; Liu, Qian; Jia, Zhaojun; Xu, Xuchen; Shi, Yuying; Cheng, Yan; Zheng, Yufeng; Xi, Tingfei; Wei, Shicheng

2013-11-01

Novel ternary graphene oxide-hyaluronic acid-hydroxyapatite (GO-HY-HA) nanocomposite coatings were prepared on Ti substrate using anodic electrophoretic deposition (EPD). Hyaluronic acid was employed as charging additive and dispersion agent during EPD. The kinetics and mechanism of the deposition, and the microstructure of the coated samples were investigated using scanning electron microscopy, X-ray diffraction, Raman spectrum, thermo-gravimetric analysis, and microscopic Fourier transform infrared analysis. The results showed that the addition of GO sheets into the HY-HA suspensions could increase the deposition rate and inhibit cracks creation and propagation in the coatings. The corrosion resistant of the resulting samples were evaluated using potentiodynamic polarization method in simulated body fluid, and the GO-HY-HA coatings could effectively improve the anti-corrosion property of the Ti substrate.

Electrically conductive poly-ɛ-caprolactone/polyethylene glycol/multi-wall carbon nanotube nanocomposite scaffolds coated with fibrin glue for myocardial tissue engineering

NASA Astrophysics Data System (ADS)

Mehdikhani, Mehdi; Ghaziof, Sharareh

2018-01-01

In this research, poly-ɛ-caprolactone (PCL), polyethylene glycol (PEG), multi-wall carbon nanotubes (MWCNTs), and nanocomposite scaffolds containing 0.5 and 1% (w/w) MWCNTs coated with fibrin glue (FG) were prepared via solvent casting and freeze-drying technique for cardiac tissue engineering. Scanning electron microscopy, transmission electron microscopy, Fourier transform-infrared spectroscopy, and X-ray diffraction were used to characterize the samples. Furthermore, mechanical properties, electrical conductivity, degradation, contact angle, and cytotoxicity of the samples were evaluated. Results showed the uniform distribution of the MWCNTs with some aggregates in the prepared nanocomposite scaffolds. The scaffolds containing 1% (w/w) MWCNTs with and without FG coating illustrated optimum modulus of elasticity, high electrical conductivity, and wettability compared with PCL/PEG and PCL/PEG/0.5%(w/w) MWCNTs' scaffolds. FG coating enhanced electrical conductivity and cell response, and increased wettability of the constructs. The prepared scaffolds were degraded significantly after 60 days of immersion in PBS. Meanwhile, the nanocomposite containing 1% (w/w) MWCNTs with FG coating (S3) showed proper spreading and viability of the myoblasts seeded on it after 1, 4, and 7 days of culture. The scaffold containing 1% (w/w) MWCNTs with FG coating demonstrated optimal properties including acceptable mechanical properties, proper wettability, high electrical conductivity, satisfactory degradation, and excellent myoblasts response to it.

Corrosion-protective coatings from electrically conducting polymers

NASA Technical Reports Server (NTRS)

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

1991-01-01

In a joint effort between NASA Kennedy and LANL, electrically conductive polymer coatings were developed as corrosion protective coatings for metal surfaces. At NASA Kennedy, the launch environment consist of marine, severe solar, and intermittent high acid and/or elevated temperature conditions. Electrically conductive polymer coatings were developed which impart corrosion resistance to mild steel when exposed to saline and acidic environments. Such coatings also seem to promote corrosion resistance in areas of mild steel where scratches exist in the protective coating. Such coatings appear promising for many commercial applications.

Protective broadband window coatings

NASA Astrophysics Data System (ADS)

Askinazi, Joel; Narayanan, Authi A.

1997-06-01

Optical windows employed in current and future airborne and ground based optical sensor systems are required to provide long service life under extreme environmental conditions including blowing sand and high speed rain. State of the art sensor systems are employing common aperture windows which must provide optical bandpasses from the TV to the LWIR. Operation Desert Storm experience indicates that current optical coatings provide limited environmental protection which adversely affects window life cycle cost. Most of these production coatings also have limited optical bandpasses (LWIR, MWIR, or TV-NIR). A family of optical coatings has been developed which provide a significant increase in rain and sand impact protection to current optical window materials. These coatings can also be tailored to provide either narrow optical bandwidth (e.g., LWIR) or broadband transmittance (TV- LWIR). They have been applied to a number of standard optical window materials. These coating have successfully completed airborne rain and sand abrasion test with minimal impact on optical window performance. Test results are presented. Low cost service life is anticipated as well as the ability to operate windows in even more taxing environments than currently feasible.

Superamphiphobic and Electroactive Nanocomposite toward Self-Cleaning, Antiwear, and Anticorrosion Coatings.

PubMed

Yuan, Ruixia; Wu, Shiqi; Yu, Peng; Wang, Baohui; Mu, Liwen; Zhang, Xiguang; Zhu, Yixing; Wang, Bing; Wang, Huaiyuan; Zhu, Jiahua

2016-05-18

Multifunctional coatings are in urgent demand in emerging fields. In this work, nanocomposite coatings with extraordinary self-cleaning, antiwear, and anticorrosion properties were prepared on aluminum substrate by a facile spraying technique. Core-shell structured polyaniline/functionalized carbon nanotubes (PANI/fCNTs) composite and nanosized silica were synergistically integrated into ethylene tetrafluoroethylene (ETFE) matrix to construct lotus-leaf-like structures, and 1H,1H,2H,2H- perfluorooctyltriethoxysilane (POTS) was used to decrease the surface energy. The composite coating with 6 wt % PANI/fCNTs possesses superamphiphobic property, with contact angles of 167°, 163°, and 159° toward water, glycerol, and ethylene glycol, respectively. This coating demonstrates stable nonwetting performance over a wide temperature range (<400 °C), as well as outstanding self-cleaning ability to prevent contamination by sludge, concentrated H2SO4, and ethylene glycol. Superamphiphobic surface property could be maintained even after 45 000 times abrasion or bending test for 30 times. The coating displayed strong adhesive ability (grade 1 according to the GB/T9286) on the etched aluminum plate. The superamphiphobic surface could be retained after immersion in 1 mol/L HCl and 3.5 wt % NaCl solutions for 60 and 90 d, respectively. It should be noted that this coating reveals significantly improved anticorrosion performance as compared to the bare ETFE coating and ETFE composite coating without PANI/fCNTs. Such coatings with integrated functionalities offer promising self-cleaning and anticorrosion applications under erosive/abrasive environment.

Protective coatings for sensitive materials

DOEpatents

Egert, C.M.

1997-08-05

An enhanced protective coating is disclosed to prevent interaction between constituents of the environment and devices that can be damaged by those constituents. This coating is provided by applying a synergistic combination of diffusion barrier and physical barrier materials. These materials can be, for example, in the form of a plurality of layers of a diffusion barrier and a physical barrier, with these barrier layers being alternated. Further protection in certain instances is provided by including at least one layer of a getter material to actually react with one or more of the deleterious constituents. The coating is illustrated by using alternating layers of an organic coating (such as Parylene-C{trademark}) as the diffusion barrier, and a metal coating (such as aluminum) as the physical barrier. For best results there needs to be more than one of at least one of the constituent layers. 4 figs.

MTA-enriched nanocomposite TiO(2)-polymeric powder coatings support human mesenchymal cell attachment and growth.

PubMed

Shi, Wen; Mozumder, Mohammad Sayem; Zhang, Hui; Zhu, Jesse; Perinpanayagam, Hiran

2012-10-01

The objective of the study described in this paper was the development of novel polymer/ceramic nanocomposite coatings for implants through the application of ultrafine powder coating technology. Polyester resins were combined with µm-sized TiO(2) (25%) as the biocompatibility agent, nTiO(2) (0.5%) as the flow additive and mineral trioxide aggregates (ProRoot® MTA, 5%) as bioactive ceramics. Ultrafine powders were prepared and applied to titanium to create continuous polymeric powder coatings (PPCs) through the application of electrostatic ultrafine powder coating technology. Energy dispersive x-ray analysis confirmed that MTA had been incorporated into the PPCs, and elemental mapping showed that it had formed small clusters that were evenly distributed across the surface. Scanning electron microscopy (SEM) revealed continuous and smooth, but highly textured surface coatings that contrasted with the scalloped appearance of commercially pure titanium (cpTi) controls. Atomic force microscopy revealed intricate nano-topographies with an abundance of submicron-sized pits and nano-projections, evenly dispersed across their surfaces. Inverted fluorescence microscopy, SEM and cell counts showed that human embryonic palatal mesenchymal cells attached and spread out onto PPC and MTA-enriched PPCs within 24 h. Mitochondrial enzyme activity measured viable and metabolically active cells on all of the surfaces. After 72 h of growth, cell counts and metabolic activity were significantly higher (P < 0.05) on the grey-MTA enriched PPC surfaces, than on unmodified PPC and cpTi. The novel polymer/ceramic nanocomposites that were created with ultrafine powder coating technology were continuous, homogenous and nano-rough coatings that enhanced human mesenchymal cell attachment and growth.

Anti-graffiti nanocomposite materials for surface protection of a very porous stone

NASA Astrophysics Data System (ADS)

Licchelli, Maurizio; Malagodi, Marco; Weththimuni, Maduka; Zanchi, Chiara

2014-09-01

The preservation of stone substrates from defacement induced by graffiti represents a very challenging task, which can be faced by applying suitable protective agents on the surface. Although different anti-graffiti materials have been developed, it is often found that their effectiveness is unsatisfactory, most of all when applied on very porous stones, e.g. Lecce stone. The aim of this work was to study the anti-graffiti behaviour of new nanocomposite materials obtained by dispersing montmorillonite nanoparticles (layered aluminosilicates with a high-aspect ratio) into a fluorinated polymer matrix (a fluorinated polyurethane based on perfluoropolyether blocks). Polymeric structure was modified by inducing a cross-linking process, in order to produce a durable anti-graffiti coating with enhanced barrier properties. Several composites were prepared using a naturally occurring and an organically modified montmorillonite clay (1, 3, and 5 % w/w concentrations). Materials were applied on Lecce stone specimens, and then their treated surfaces were soiled by a black ink permanent marker or by a black acrylic spray paint. Several repeated staining/cleaning cycles were performed in order to evaluate anti-graffiti effectiveness. Colorimetric measurements were selected to assess the anti-graffiti performance. It was found that the presence of 3 % w/w organically modified montmorillonite in the polymer coating is enough to induce a durable anti-graffiti effect when the stone surface is stained by acrylic paint. Less promising results are obtained when staining by permanent marker is considered as all the investigated treatments afford a reasonable protection from ink only for the first staining/cleaning cycle.

Method for smoothing the surface of a protective coating

DOEpatents

Sangeeta, D.; Johnson, Curtis Alan; Nelson, Warren Arthur

2001-01-01

A method for smoothing the surface of a ceramic-based protective coating which exhibits roughness is disclosed. The method includes the steps of applying a ceramic-based slurry or gel coating to the protective coating surface; heating the slurry/gel coating to remove volatile material; and then further heating the slurry/gel coating to cure the coating and bond it to the underlying protective coating. The slurry/gel coating is often based on yttria-stabilized zirconia, and precursors of an oxide matrix. Related articles of manufacture are also described.

Epitaxial YBa2Cu3O7-x nanocomposite films and coated conductors from BaMO3 (M = Zr, Hf) colloidal solutions

NASA Astrophysics Data System (ADS)

Obradors, X.; Puig, T.; Li, Z.; Pop, C.; Mundet, B.; Chamorro, N.; Vallés, F.; Coll, M.; Ricart, S.; Vallejo, B.; Pino, F.; Palau, A.; Gázquez, J.; Ros, J.; Usoskin, A.

2018-04-01

Superconducting nanocomposites are the best material choice to address the performance required in power applications and magnets working under high magnetic fields. However, it is still challenging to sort out how to achieve the highest superconducting performance using attractive and competitive manufacturing processes. Colloidal solutions have been recently developed as a novel and very promising low cost route to manufacture nanocomposite coated conductors. Well dispersed and stabilized preformance nanoparticle solutions are first prepared with high concentrations and then mixed with the YBa2Cu3O7 metalorganic precursor solutions to generate colloidal solutions to grow the nanocomposite films. Here we demonstrate, for the first time, that non-reactive BaZrO3 and BaHfO3 perovskite preformed nanoparticles are suitable for growing high quality thin and thick films, and coated conductors with a homogeneous distribution and controlled particle size using this fabrication method. Additionally, we extend the nanoparticle content of the nanocomposites up to 20%-25% mol without any degradation of the superconducting properties. Thick nanocomposite films, up to 0.8 μm, have been prepared with a single deposition of low-fluorine solutions using an ink jet printing dispenser and we demonstrate that the preformed nanoparticles display only a very limited coarsening during the growth process and so high critical current densities J c (B) under high magnetic fields. These films show the highest critical currents achieved so far based on the colloidal solution approach, I c = 220 A/cm-w at 77 K and self-field, and they still have a high potential for further increase in the film thickness. Finally, we also show that nanocomposite YBa2Cu3O7-BaZrO3 coated conductors based on an alternating beam assisted deposited YSZ buffer layer on stainless steel metallic substrates can be developed based on these novel colloidal solutions. Non-reactive preformed oxide perovskite

Structure and corrosion behaviour of electrodeposited Co-Mo/TiO2 nano-composite coatings

NASA Astrophysics Data System (ADS)

Krawiec, H.; Vignal, V.; Latkiewicz, M.; Herbst, F.

2018-01-01

The structure and the corrosion behaviour in the Ringer's solution of Co-Mo/TiO2 nano-composite coatings have been investigated. They consist of aggregates of TiO2 nanoparticles uniformly distributed in a Co-Mo alloy matrix (crystallite size of about 2 nm). Both nodular (thickness less than 20 μm) and globular structures (thickness greater than 20 μm) have been observed using field-emission scanning electron microscopy. Under potentiostatic control (in Ringer's solution), oxidation of the coating first occurs followed by (with increasing applied potential) both oxidation and selective dissolution of Co. At the OCP value, Co is oxidized in the form of Co2+-based compounds (CoO, Co(OH)2 or α-CoMoO4) in the coating. This process only occurs in the outermost part of the coating. Therefore, the bulk properties of the coating are not affected after long-term ageing in the Ringer's solution at OCP.

Synthesis and magnetic property of T4 virus-supported gold-coated iron ternary nanocomposite

NASA Astrophysics Data System (ADS)

Xu, Ziming; Sun, Hongjing; Gao, Faming; Hou, Li; Li, Na

2012-12-01

Herein, we present a novel method based on the use of the symmetrical T4 bacteriophage capsid as a scaffold for preparing the gold-coated iron ternary core/shell nanostructure. Results showed that the thick gold shell was obtained to effectively protect Fe core from oxidation. Magnetic measurements showed that the nanocomposites were superparamagnetic at room temperature with a blocking temperature of about 35 K. At 3 K, its coercivity of 1142.86 Oe was larger than the existing experimental values. The magnetic property of Au/T4 was also tested, demonstrating the source of the magnetic sample arising from the Fe core only. The absorption spectrum of the Fe@Au/T4 complex was measured and compared with gold/virus. Different thickness gold shells were controlled in the synthesis by tuning the Au salt addition. On the basis of results and discussion, we further speculated the general growing mechanism of the template-supported Fe@Au process.

Smart Coatings for Corrosion Protection

NASA Technical Reports Server (NTRS)

Calle, Luz Marina; Li, Wendy; Buhrow, Jerry W.; Johnsey, Marissa N.

2016-01-01

Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. It is essential to detect corrosion when it occurs, and preferably at its early stage, so that action can be taken to avoid structural damage or loss of function. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional, smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it.

Effect of substrate temperature and gas flow ratio on the nanocomposite TiAlBN coating

NASA Astrophysics Data System (ADS)

Rosli, Z. M.; Kwan, W. L.; Juoi, J. M.

2016-07-01

Nanocomposite TiAlBN (nc-TiAlBN) coatings were successfully deposited via RF magnetron sputtering by varying the nitrogen-to-total gas flow ratio (RN), and substrate temperature (TS). All coatings were deposited on AISI 316 substrates using single Ti-Al-BN hot-pressed disc as a target. The grain size, phases, and chemical composition of the coatings were evaluated using glancing angle X-ray diffraction analysis (GAXRD) and X-ray photoelectron spectroscopy (XPS). Results showed that the grains size of the deposited nc-TiAlBN coatings were in the range of 3.5 to 5.7 nm and reached a nitride saturation state as early as 15 % RN. As the nitrogen concentration decreases, boron concentration increased from 9 at.% to 16.17 at.%. and thus, increase the TiB2 phase within the coatings. The TS, however, showed no significant effect either on the crystallographic structure, grain size, or in the chemical composition of the deposited nc-TiAlBN coating.

METHOD OF PROTECTIVELY COATING URANIUM

DOEpatents

Eubank, L.D.; Boller, E.R.

1959-02-01

A method is described for protectively coating uranium with zine comprising cleaning the U for coating by pickling in concentrated HNO/sub 3/, dipping the cleaned U into a bath of molten zinc between 430 to 600 C and containing less than 0 01% each of Fe and Pb, and withdrawing and cooling to solidify the coating. The zinccoated uranium may be given a; econd coating with another metal niore resistant to the corrosive influences particularly concerned. A coating of Pb containing small proportions of Ag or Sn, or Al containing small proportions of Si may be applied over the zinc coatings by dipping in molten baths of these metals.

Properties of Lightning Strike Protection Coatings

NASA Astrophysics Data System (ADS)

Gagne, Martin

Composite materials are being increasingly used by many industries. In the case of aerospace companies, those materials are installed on their aircraft to save weight, and thus, fuel costs. These aircraft are lighter, but the loss of electrical conductivity makes aircraft vulnerable to lightning strikes, which hit commercial aircrafts on average once per year. This makes lightning strike protection very important, and while current metallic expanded copper foils offer good protection, they increase the weight of composites. Therefore, under the CRIAQ COMP-502 project, a team of industrial partners and academic researchers are investigating new conductive coatings with the following characteristics: High electromagnetic protection, high mechanical resistance, good environmental protection, manufacturability and moderate cost. The main objectives of this thesis, as part of this project, was to determine the main characteristics, such as electrical and tribomechanical properties, of conductive coatings on composite panels. Their properties were also to be tested after destructive tests such as current injection and environmental testing. Bombardier Aerospace provided the substrate, a composite of carbon fiber reinforced epoxy matrix, and the current commercial product, a surfacing film that includes an expanded copper foil used to compare with the other coatings. The conductive coatings fabricated by the students are: silver nanoparticles inside a binding matrix (PEDOT:PSS or a mix of Epoxy and PEDOT:PSS), silvered carbon nanofibers embedded in the surfacing film, cold sprayed tin, graphene oxide functionalized with silver nanowires, and electroless plated silver. Additionally as part of the project and thesis, magnetron sputtered aluminum coated samples were fabricated. There are three main types of tests to characterize the conductive coatings: electrical, mechanical and environmental. Electrical tests consist of finding the sheet resistance and specific resistivity

Enhanced room-temperature magnetoresistance in self-assembled Ag-coated multiphasic chromium oxide nanocomposites.

PubMed

Dwivedi, S; Biswas, S

2016-09-14

Self-assembled Ag-coated multiphasic diluted magnetic chromium oxide nanocomposites were developed by a facile chemical synthesis route involving a reaction of CrO3 in the presence of Ag(+) ions in an aqueous solution of poly-vinyl alcohol (PVA) and sucrose. The tiny ferromagnetic single domains of tetragonal and orthorhombic CrO2 (t-CrO2 and o-CrO2) embedded in a dominantly insulating matrix of antiferromagnetic Cr2O3 and Cr3O8, and paramagnetic CrO3 and Cr2O, with a correlated diamagnetic thin and discontinuous shell layer of Ag efficiently tailor useful magnetic and room-temperature magnetoresistance (RTMR) properties. The t-CrO2, o-CrO2, possible canted ferromagnetism due to spin disorder in the matrix components, and the associated exchange interactions are the elements responsible for the observed ferromagnetism in the composite structure. The chain of ferromagnetic centers embedded in the composite matrix constitutes a type of magnetic tunnel junction through which spin-polarized electrons can effectively move without significant local interruptions. Electrical transport measurements showed that the spin-dependent tunneling (SDT) mechanism in the engineered microstructure of the nanocomposites exists even at room temperature (RT). A typical sample unveils a markedly enhanced RTMR-value, e.g., -80% at an applied field (H) of 3 kOe, compared to the reported values for compacted CrO2 powders or composites. The enhanced RTMR-value observed in the Coulomb blockade regime appears not only due to the considerably suppressed spin flipping at RT but primarily due to a highly effective SDT mechanism through an interlinked structure of Ag-coated multiphasic chromium oxide nanocomposites.

49 CFR 192.461 - External corrosion control: Protective coating.

Code of Federal Regulations, 2011 CFR

2011-10-01

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

49 CFR 192.461 - External corrosion control: Protective coating.

Code of Federal Regulations, 2010 CFR

2010-10-01

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

Paper-Thin Coating Offers Maximum Protection

NASA Technical Reports Server (NTRS)

2001-01-01

Wessex Incorporated has recently taken a technology that was originally developed for NASA as a protective coating for ceramic materials used in heatshields for space vehicles, and modified it for use in applications such as building materials, machinery, and transportation. The technology, developed at NASA Ames Research Center as a protective coating for flexible ceramic composites (PCC), is environmentally safe, water-based, and contains no solvents. Many other flame-retardant materials contain petroleum-based components, which can produce toxic smoke under flame. Wessex versions of PCC can be used to shield ceramics, wood, plasterboard, steel, plastics, fiberglass, and other materials from catastrophic fires. They are extraordinarily tough and exhibit excellent resistance to thermal shock, vibration, abrasion, and mechanical damage. One thin layer of coating provides necessary protection and allows for flexibility while avoiding excessive weight disadvantages. The coating essentially reduces the likelihood of the underlying material becoming so hot that it combusts and thus inhibits the "flashover" phenomenon from occurring.

Antibacterial Ag/a-C nanocomposite coatings: The influence of nano-galvanic a-C and Ag couples on Ag ionization rates

NASA Astrophysics Data System (ADS)

Manninen, N. K.; Calderon, S.; Carvalho, I.; Henriques, M.; Cavaleiro, A.; Carvalho, S.

2016-07-01

Biofilm formation has been pointed as a major concern in different industrial applications, namely on biomedical implants and surgical instruments, which has prompted the development of new strategies for production of efficient antimicrobial surfaces. In this work, nano-galvanic couples were created to enhance the antibacterial properties of silver, by embedding it into amorphous carbon (a-C) matrix. The developed Ag/a-C nanocomposite coatings, deposited by magnetron sputtering, revealed an outstanding antibacterial activity against Staphylococcus epidermidis, promoting a total reduction in biofilm formation with no bacteria counts in all dilution. The open circuit potential (OCP) tests in 0.9% NaCl confirmed that a-C shows a positive OCP value, in contrast to Ag coating, thus enhancing the ionization of biocidal Ag+ due to the nano-galvanic couple activation. This result was confirmed by the inductively coupled plasma-optical emission spectroscopy (ICP-OES), which revealed a higher Ag ionization rate in the nanocomposite coating in comparison with the Ag coating. The surface of Ag/a-C and Ag coatings immersed in 0.9% NaCl were monitored by scanning electron microscopy (SEM) over a period of 24 h, being found that the Ag ionization determined by ICP-OES was accompanied by an Ag nanoparticles coalescence and agglomeration in Ag/a-C coating.

Photo-Catalytic Properties of TiO2 Supported on MWCNTs, SBA-15 and Silica-Coated MWCNTs Nanocomposites.

PubMed

Ramoraswi, Nteseng O; Ndungu, Patrick G

2015-12-01

Mesoporous silica, specifically SBA-15, acid-treated multi-walled carbon nanotubes and a hybrid nanocomposite of SBA-15 coated onto the sidewalls acid-treated multi-walled carbon nanotubes (CNTs) were prepared and used as supports for anatase TiO2. Sol-gel methods were adapted for the synthesis of selected supports and for coating the materials with selected wt% loading of titania. Physical and chemical properties of the supports and catalyst composite materials were investigated by powder X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis, scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), UV-vis diffuse reflectance spectroscopy and fluorescence spectroscopy. The photo-activity of the catalyst composites were evaluated on the decolorisation of methylene blue as a model pollutant. Coating CNTs with SBA-15 improved the thermal stability and textural properties of the nanotubes. All supported titania composites had high surface areas (207-301 m(2)/g), altered band gap energies and reduced TiO2 crystallite sizes. The TiO2/SBA-CNT composite showed enhanced photo-catalytic properties and activity than the TiO2/SBA-15 and TiO2/CNT composites. In addition, an interesting observation was noted with the TiO2/SBA-15 nanocomposites, which had a significantly greater photo-catalytic activity than the TiO2/CNT nanocomposites in spite of the high electron-hole recombination phenomena observed with the photoluminescence results. Discussions in terms of morphological, textural and physical-chemical aspects to account for the result are presented.

Photo-Catalytic Properties of TiO2 Supported on MWCNTs, SBA-15 and Silica-Coated MWCNTs Nanocomposites

NASA Astrophysics Data System (ADS)

Ramoraswi, Nteseng O.; Ndungu, Patrick G.

2015-10-01

Mesoporous silica, specifically SBA-15, acid-treated multi-walled carbon nanotubes and a hybrid nanocomposite of SBA-15 coated onto the sidewalls acid-treated multi-walled carbon nanotubes (CNTs) were prepared and used as supports for anatase TiO2. Sol-gel methods were adapted for the synthesis of selected supports and for coating the materials with selected wt% loading of titania. Physical and chemical properties of the supports and catalyst composite materials were investigated by powder X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis, scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), UV-vis diffuse reflectance spectroscopy and fluorescence spectroscopy. The photo-activity of the catalyst composites were evaluated on the decolorisation of methylene blue as a model pollutant. Coating CNTs with SBA-15 improved the thermal stability and textural properties of the nanotubes. All supported titania composites had high surface areas (207-301 m2/g), altered band gap energies and reduced TiO2 crystallite sizes. The TiO2/SBA-CNT composite showed enhanced photo-catalytic properties and activity than the TiO2/SBA-15 and TiO2/CNT composites. In addition, an interesting observation was noted with the TiO2/SBA-15 nanocomposites, which had a significantly greater photo-catalytic activity than the TiO2/CNT nanocomposites in spite of the high electron-hole recombination phenomena observed with the photoluminescence results. Discussions in terms of morphological, textural and physical-chemical aspects to account for the result are presented.

Hydroxyapatite-anatase-carbon nanotube nanocomposite coatings fabricated by electrophoretic codeposition for biomedical applications.

PubMed

Zhang, Bokai; Kwok, Chi Tat

2011-10-01

In order to eliminate micro-cracks in the monolithic hydroxyapatite (HA) and composite hydroxyapatite/carbon nanotube (HA/CNT) coatings, novel HA/TiO(2)/CNT nanocomposite coatings on Ti6Al4V were attempted to fabricate by a single-step electrophoretic codeposition process for biomedical applications. The electrophoretically deposited layers with difference contents of HA, TiO(2) (anatase) and CNT nanoparticles were sintered at 800°C for densification with thickness of about 7-10 μm. A dense and crack-free coating was achieved with constituents of 85 wt% HA, 10 wt% TiO(2) and 5 wt% CNT. Open-circuit potential measurements and cyclic potentiodynamic polarization tests were used to investigate the electrochemical corrosion behavior of the coatings in vitro conditions (Hanks' solution at 37°C). The HA/TiO(2)/CNT coatings possess higher corrosion resistance than that of the Ti6Al4V substrate as reflected by nobler open circuit potential and lower corrosion current density. In addition, the surface hardness and adhesion strength of the HA/TiO(2)/CNT coatings are higher than that of the monolithic HA and HA/CNT coatings without compromising their apatite forming ability. The enhanced properties were attributed to the nanostructure of the coatings with the appropriate TiO(2) and CNT contents for eliminating micro-cracks and micro-pores.

Article having an improved platinum-aluminum-hafnium protective coating

NASA Technical Reports Server (NTRS)

Nagaraj, Bangalore Aswatha (Inventor); Williams, Jeffrey Lawrence (Inventor)

2005-01-01

An article protected by a protective coating has a substrate and a protective coating having an outer layer deposited upon the substrate surface and a diffusion zone formed by interdiffusion of the outer layer and the substrate. The protective coating includes platinum, aluminum, no more than about 2 weight percent hafnium, and substantially no silicon. The outer layer is substantially a single phase.

The effects of phase transformation on the structure and mechanical properties of TiSiCN nanocomposite coatings deposited by PECVD method

NASA Astrophysics Data System (ADS)

Abedi, Mohammad; Abdollah-zadeh, Amir; Bestetti, Massimiliano; Vicenzo, Antonello; Serafini, Andrea; Movassagh-Alanagh, Farid

2018-06-01

In the present study, the effects of phase transformations on the structure and mechanical properties of TiSiCN coatings were investigated. TiSiCN nanocomposite coatings were deposited on AISI H13 hot-work tool steel by a pulsed direct current plasma-enhanced chemical vapor deposition process at 350 or 500 °C, using TiCl4 and SiCl4 as the precursors of Ti and Si, respectively, in a CH4/N2/H2/Ar plasma as the source of carbon and nitrogen and reducing environment. Some samples deposited at 350 °C were subsequently annealed at 500 °C under Ar atmosphere. Super hard self-lubricant TiSiCN coatings, having nanocomposite structure consisting of TiCN nanocrystals and amorphous carbon particles embedded in an amorphous SiCNx matrix, formed through spinodal decomposition in the specimens deposited or annealed at 500 °C. In addition, it was revealed that either uncomplete or relatively coarse phase segregation of titanium compounds was achieved during deposition at 350 °C and 500 °C, respectively. On the contrary, by deposition at 350 °C followed by annealing at 500 °C, a finer structure was obtained with a sensible improvement of the mechanical properties of coatings. Accordingly, the main finding of this work is that significant enhancement in key properties of TiSiCN coatings, such as hardness, adhesion and friction coefficient, can be obtained by deposition at low temperature and subsequent annealing at higher temperature, thanks to the formation of a fine grained nanocomposite structure.

Protective coatings for composite tubes in space applications

NASA Technical Reports Server (NTRS)

Dursch, Harry W.; Hendricks, Carl L.

1987-01-01

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

Protective coatings for composite tubes in space applications

NASA Technical Reports Server (NTRS)

Dursch, Harry W.; Hendricks, Carl L.

1987-01-01

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

Development of composite tube protective coatings

NASA Technical Reports Server (NTRS)

Dursch, H.; Hendricks, C.

1986-01-01

Protective coatings for graphite/epoxy (Gr/Ep) tubular structures proposed for the Space Station are evaluated. The program was divided into four parts; System Definition, Coating Concept Selection and Evaluation, Scale-up and Assembly, and Reporting. System Definition involved defining the structural and environmental properties required of the Gr/Ep tubes. The prepreg and ply sequence selected was a P75S/934 (O2, + or - 20, O2)sub s layup which meets the various structural requirements of the Space Station. Coating Concept and Selection comprised the main emphasis of the effort. Concepts for protectively coating the Gr/Ep tubes included the use of metal foil and electroplating. The program results demonstrated that both phosphoric and chromic acid anodized Al foil provided adequate adhesion to the Gr/Ep tubes and stability of optical properties when subjected to atomic oxygen and thermal cycling representative of the LEO environment. SiO2/Al coatings sputtered onto Al foils also resulted in an excellent protective coating. The electroplated Ni possessed unacceptable adhesion loss to the Gr/Ep tubes during atomic oxygen testing. Scale-Up and Assembly involved fabricating and wrapping 8-ft-long by 2-in-diameter Gr/EP tubes with chromic acid anodized foil and delivering these tubes, along with representative Space Station erectable end fittings, to NASA LaRC.

Ab Initio Predictions of Strong Interfaces in Transition-Metal Carbides and Nitrides for Superhard Nanocomposite Coating Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Chongze; Huang, Jingsong; Sumpter, Bobby G.

Conceiving strong interfaces represents an effective direction in the development of superhard nanocomposite materials for practical applications in protective coatings. Additionally, in the pursuit of engineering strong nanoscale interfaces between cubic rock-salt (B1) domains, we investigate using density functional theory (DFT) coherent interface models designed based on hexagonal (HX) NiAs and WC structures, as well as experiment. The DFT screening of a collection of transition-metal (M = Zr, Hf, Nb, Ta) carbides and nitrides indicates that the interface models provided by the HX polymorphs store little coherency strain and develop an energetic advantage as the valence-electron concentration increases. Finally, ourmore » result suggests that harnessing the polymorphism encountered in transition-metal (M = Zr, Hf, Nb, Ta) carbides and nitrides for interface design represents a promising strategy for advancing superhard nanomaterials.« less

Ab Initio Predictions of Strong Interfaces in Transition-Metal Carbides and Nitrides for Superhard Nanocomposite Coating Applications

DOE PAGES

Hu, Chongze; Huang, Jingsong; Sumpter, Bobby G.; ...

2018-04-19

Conceiving strong interfaces represents an effective direction in the development of superhard nanocomposite materials for practical applications in protective coatings. Additionally, in the pursuit of engineering strong nanoscale interfaces between cubic rock-salt (B1) domains, we investigate using density functional theory (DFT) coherent interface models designed based on hexagonal (HX) NiAs and WC structures, as well as experiment. The DFT screening of a collection of transition-metal (M = Zr, Hf, Nb, Ta) carbides and nitrides indicates that the interface models provided by the HX polymorphs store little coherency strain and develop an energetic advantage as the valence-electron concentration increases. Finally, ourmore » result suggests that harnessing the polymorphism encountered in transition-metal (M = Zr, Hf, Nb, Ta) carbides and nitrides for interface design represents a promising strategy for advancing superhard nanomaterials.« less

Ranking protective coatings: Laboratory vs. field experience

NASA Astrophysics Data System (ADS)

Conner, Jeffrey A.; Connor, William B.

1994-12-01

Environmentally protective coatings are used on a wide range of gas turbine components for survival in the harsh operating conditions of engines. A host of coatings are commercially available to protect hot-section components, ranging from simple aluminides to designer metallic overlays and ceramic thermal barrier coatings. A variety of coating-application processes are available, and they range from simple pack cementation processing to complex physical vapor deposition, which requires multimillion dollar facilities. Detailed databases are available for most coatings and coating/process combinations for a range of laboratory tests. Still, the analysis of components actually used in engines often yields surprises when compared against predicted coating behavior from laboratory testing. This paper highlights recent work to develop new laboratory tests that better simulate engine environments. Comparison of in-flight coating performance as well as industrial and factory engine testing on a range of hardware is presented along with laboratory predictions from standard testing and from recently developed cyclic burner-rig testing.

Preparation, characterization, and biological properties of organic-inorganic nanocomposite coatings on titanium substrates prepared by sol-gel.

PubMed

Catauro, Michelina; Bollino, Flavia; Papale, Ferdinando

2014-02-01

When surface-reactive (bioactive) coatings are applied to medical implants by means of the sol-gel dip-coating technique, the biological proprieties of the surface of the implant can be locally modified to match the properties of the surrounding tissues to provide a firm fixation of the implant. The aim of this study has been to synthesize, via sol-gel, organoinorganic nanoporous materials and to dip-coat a substrate to use in dental applications. Different systems have been prepared consisting of an inorganic zirconium-based matrix, in which a biodegradable polymer, the poly-ε-caprolactone was incorporated in different percentages. The materials synthesized by the sol-gel process, before gelation, when they were still in sol phase, have been used to coat a titanium grade 4 (Ti-4) substrate to change its surface biological properties. Thin films have been obtained by means of the dip-coating technique. A microstructural analysis of the obtained coatings was performed using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy. The biological proprieties have been investigated by means of tests in vitro. The bone-bonding capability of the nanocomposite films has been evaluated by examining the appearance of apatite on their surface when plunged in a simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma. The examination of apatite formation on the nanocomposites, after immersion in SBF, has been carried out by SEM equipped with energy-dispersive X-ray spectroscopy. To evaluate cells-materials interaction, human osteosarcoma cell line (Saos-2) has been seeded on specimens and cell vitality evaluated by WST-8 assay. © 2013 Wiley Periodicals, Inc.

SWCNTs-based nanocomposites as sensitive coatings for advanced fiber optic chemical nanosensors

NASA Astrophysics Data System (ADS)

Consales, M.; Crescitelli, A.; Penza, M.; Aversa, P.; Giordano, M.; Cutolo, A.; Cusano, A.

2008-04-01

In this work, the feasibility of exploiting novel Cadmium Arachidate (CdA)/single-walled carbon nanotubes (SWCNTs) based composites as sensitive coatings for the development of robust and high performances optoelectronic chemosensors able to work in liquid environments has been investigated and proved. Here, nano-composite sensing layers have been transferred upon the distal end of standard optical fibers by the Langmuir-Blodgett (LB) technique. Reflectance measurements have been carried out to monitor ppm concentration of chemicals in water through the changes in the optical and geometrical features of the sensing overlay induced by the interaction with the analyte molecules. Preliminary experimental results evidence that such nanoscale coatings integrated with the optical fiber technology offers great potentialities for the room temperature detection of chemical traces in water and lead to significant improvements of the traditional fiber optic sensors based on SWCNTs layers.

Surface Coating of Oxide Powders: A New Synthesis Method to Process Biomedical Grade Nano-Composites

PubMed Central

Palmero, Paola; Montanaro, Laura; Reveron, Helen; Chevalier, Jérôme

2014-01-01

Composite and nanocomposite ceramics have achieved special interest in recent years when used for biomedical applications. They have demonstrated, in some cases, increased performance, reliability, and stability in vivo, with respect to pure monolithic ceramics. Current research aims at developing new compositions and architectures to further increase their properties. However, the ability to tailor the microstructure requires the careful control of all steps of manufacturing, from the synthesis of composite nanopowders, to their processing and sintering. This review aims at deepening understanding of the critical issues associated with the manufacturing of nanocomposite ceramics, focusing on the key role of the synthesis methods to develop homogeneous and tailored microstructures. In this frame, the authors have developed an innovative method, named “surface-coating process”, in which matrix oxide powders are coated with inorganic precursors of the second phase. The method is illustrated into two case studies; the former, on Zirconia Toughened Alumina (ZTA) materials for orthopedic applications, and the latter, on Zirconia-based composites for dental implants, discussing the advances and the potential of the method, which can become a valuable alternative to the current synthesis process already used at a clinical and industrial scale. PMID:28788117

Possible alternatives to critical elements in coatings for extreme applications

NASA Astrophysics Data System (ADS)

Grilli, Maria Luisa; Valerini, Daniele; Piticescu, Radu Robert; Bellezze, Tiziano; Yilmaz, Mehmet; Rinaldi, Antonio; Cuesta-López, Santiago; Rizzo, Antonella

2018-03-01

Surface functionalisation and protection have been used since a long time for improving specific properties of materials such as lubrication, water repellence, brightness, and for increasing durability of objects and tools. Among the different kinds of surface treatments used to achieve the required properties, the use of coatings is fundamental to guarantee substrate durability in harsh environments. Extreme working conditions of temperature, pressure, irradiation, wear and corrosion occur in several applications, thus very often requiring bulk material protection by means of coatings. In this study, three main classes of coatings used in extreme conditions are considered: i) hard and superhard coatings for application in machining tools, ii) coatings for high temperatures (thermal barrier coatings), and iii) coatings against corrosion. The presence of critical elements in such coatings (Cr, Y, W, Co, etc.) is analysed and the possibility to use CRMs-free substitutes is reviewed. The role of multilayers and nanocomposites in tailoring coating performances is also discussed for thermal barrier and superhard coatings.

Protective Coats For Zinc-Rich Primers

NASA Technical Reports Server (NTRS)

Macdowell, Louis G, III

1993-01-01

Report describes tests of topcoats for inorganic zinc-rich primers on carbon steel. Topcoats intended to provide additional protection against corrosion in acidic, salty seacoast-air/rocket-engine-exhaust environment of Space Shuttle launch site. Tests focused on polyurethane topcoats on epoxy tie coats on primers. Part of study involved comparison between "high-build" coating materials and thin-film coating materials.

Effects of alpha-zirconium phosphate on thermal degradation and flame retardancy of transparent intumescent fire protective coating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xing, Weiyi; Zhang, Ping; Song, Lei

2014-01-01

Graphical abstract: - Highlights: • A transparent intumescent fire protective coating was obtained by UV-cured technology. • OZrP could enhance the thermal stability and anti-oxidation of the coating. • OZrP could reduce the combustion properties of the coatings. - Abstract: Organophilic alpha-zirconium phosphate (OZrP) was used to improve the thermal and fire retardant behaviors of the phenyl di(acryloyloxyethyl)phosphate (PDHA)-triglycidyl isocyanurate acrylate (TGICA)-2-phenoxyethyl acrylate (PHEA) (PDHA-TGICA-PHEA) coating. The morphology of nanocomposite coating was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effect of OZrP on the flame retardancy, thermal stability, fireproofing time and char formation of the coatingsmore » was investigated by microscale combustion calorimeter (MCC), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), laser Raman spectroscopy (LRS) and scanning electric microscope (SEM). The results showed that by adding OZrP, the peak heat release rate and total heat of combustion were significantly reduced. The highest improvement was achieved with 0.5 wt% OZrP. XPS analysis indicated that the performance of anti-oxidation of the coating was improved with the addition of OZrP, and SEM images showed that a good synergistic effect was obtained through a ceramic-like layer produced by OZrP covered on the surface of char.« less

Carbon fiber CVD coating by carbon nanostructured for space materials protection against atomic oxygen

NASA Astrophysics Data System (ADS)

Pastore, Roberto; Bueno Morles, Ramon; Micheli, Davide

2016-07-01

adhesion and durability in the environment. Though these coatings are efficient in protecting polymer composites, their application imposes severe constraints. Their thermal expansion coefficients may differ markedly from those of polymer composite substrates: as a result, cracks develop in the coatings on thermal cycling and AO can penetrate through them to the substrate. In addition to the technicalities of forming an effective barrier, such factors as cost, convenience of application and ease of repair are important considerations in the selection of a coating for a particular application. The latter issues drive the aerospace research toward the development of novel light composite materials, like the so called polymer nanocomposites, which are materials with a polymer matrix and a filler with at least one dimension less than 100 nanometers. Current interest in nanocomposites has been generated and maintained because nanoparticle-filled polymers exhibit unique combinations of properties not achievable with traditional composites. These combinations of properties can be achieved because of the small size of the fillers, the large surface area the fillers provide, and in many cases the unique properties of the fillers themselves. In particular, the carbon fiber-based polymeric composite materials are the basic point of interest: the aim of the present study is to find new solution to produce carbon fiber-based composites with even more upgraded performances. One intriguing strategy to tackle such an issue has been picked out in the coupling between the carbon fibers and the carbon nanostructures. That for two main reasons: first, carbon nanostructures have shown fancy potentialities for any kind of technological applications since their discovery, second, the chemical affinity between fiber and nanostructure (made of the same element) should be a likely route to approach the typical problems due to thermo-mechanical compatibility. This work is joined in such framework

Thermal Alternating Polymer Nanocomposite (TAPNC) Coating Designed to Prevent Aerodynamic Insect Fouling

PubMed Central

Bayer, Ilker S.; Krishnan, K. Ghokulla; Robison, Robert; Loth, Eric; Berry, Douglas H.; Farrell, Thomas E.; Crouch, Jeffrey D.

2016-01-01

Insect residue adhesion to moving surfaces such as turbine blades and aircraft not only causes surface contamination problems but also increases drag on these surfaces. Insect fouling during takeoff, climb and landing can result in increased drag and fuel consumption for aircraft with laminar-flow surfaces. Hence, certain topographical and chemical features of non-wettable surfaces need to be designed properly for preventing insect residue accumulation on surfaces. In this work, we developed a superhydrophobic coating that is able to maintain negligible levels of insect residue after 100 high speed (50 m/s) insect impact events produced in a wind tunnel. The coating comprises alternating layers of a hydrophobic, perfluorinated acrylic copolymer and hydrophobic surface functional silicon dioxide nanoparticles that are infused into one another by successive thermal treatments. The design of this coating was achieved as a result of various experiments conducted in the wind tunnel by using a series of superhydrophobic surfaces made by the combination of the same polymer and nanoparticles in the form of nanocomposites with varying surface texture and self-cleaning hydrophobicity properties. Moreover, the coating demonstrated acceptable levels of wear abrasion and substrate adhesion resistance against pencil hardness, dry/wet scribed tape peel adhesion and 17.5 kPa Taber linear abraser tests. PMID:27924913

Thermal Alternating Polymer Nanocomposite (TAPNC) Coating Designed to Prevent Aerodynamic Insect Fouling.

PubMed

Bayer, Ilker S; Krishnan, K Ghokulla; Robison, Robert; Loth, Eric; Berry, Douglas H; Farrell, Thomas E; Crouch, Jeffrey D

2016-12-07

Insect residue adhesion to moving surfaces such as turbine blades and aircraft not only causes surface contamination problems but also increases drag on these surfaces. Insect fouling during takeoff, climb and landing can result in increased drag and fuel consumption for aircraft with laminar-flow surfaces. Hence, certain topographical and chemical features of non-wettable surfaces need to be designed properly for preventing insect residue accumulation on surfaces. In this work, we developed a superhydrophobic coating that is able to maintain negligible levels of insect residue after 100 high speed (50 m/s) insect impact events produced in a wind tunnel. The coating comprises alternating layers of a hydrophobic, perfluorinated acrylic copolymer and hydrophobic surface functional silicon dioxide nanoparticles that are infused into one another by successive thermal treatments. The design of this coating was achieved as a result of various experiments conducted in the wind tunnel by using a series of superhydrophobic surfaces made by the combination of the same polymer and nanoparticles in the form of nanocomposites with varying surface texture and self-cleaning hydrophobicity properties. Moreover, the coating demonstrated acceptable levels of wear abrasion and substrate adhesion resistance against pencil hardness, dry/wet scribed tape peel adhesion and 17.5 kPa Taber linear abraser tests.

Thermal Alternating Polymer Nanocomposite (TAPNC) Coating Designed to Prevent Aerodynamic Insect Fouling

NASA Astrophysics Data System (ADS)

Bayer, Ilker S.; Krishnan, K. Ghokulla; Robison, Robert; Loth, Eric; Berry, Douglas H.; Farrell, Thomas E.; Crouch, Jeffrey D.

2016-12-01

Insect residue adhesion to moving surfaces such as turbine blades and aircraft not only causes surface contamination problems but also increases drag on these surfaces. Insect fouling during takeoff, climb and landing can result in increased drag and fuel consumption for aircraft with laminar-flow surfaces. Hence, certain topographical and chemical features of non-wettable surfaces need to be designed properly for preventing insect residue accumulation on surfaces. In this work, we developed a superhydrophobic coating that is able to maintain negligible levels of insect residue after 100 high speed (50 m/s) insect impact events produced in a wind tunnel. The coating comprises alternating layers of a hydrophobic, perfluorinated acrylic copolymer and hydrophobic surface functional silicon dioxide nanoparticles that are infused into one another by successive thermal treatments. The design of this coating was achieved as a result of various experiments conducted in the wind tunnel by using a series of superhydrophobic surfaces made by the combination of the same polymer and nanoparticles in the form of nanocomposites with varying surface texture and self-cleaning hydrophobicity properties. Moreover, the coating demonstrated acceptable levels of wear abrasion and substrate adhesion resistance against pencil hardness, dry/wet scribed tape peel adhesion and 17.5 kPa Taber linear abraser tests.

Temporary coatings for protection of microelectronic devices during packaging

DOEpatents

Peterson, Kenneth A.; Conley, William R.

2005-01-18

The present invention relates to a method of protecting a microelectronic device during device packaging, including the steps of applying a water-insoluble, temporary protective coating to a sensitive area on the device; performing at least one packaging step; and then substantially removing the protective coating, preferably by dry plasma etching. The sensitive area can include a released MEMS element. The microelectronic device can be disposed on a wafer. The protective coating can be a vacuum vapor-deposited parylene polymer, silicon nitride, metal (e.g. aluminum or tungsten), a vapor deposited organic material, cynoacrylate, a carbon film, a self-assembled monolayered material, perfluoropolyether, hexamethyldisilazane, or perfluorodecanoic carboxylic acid, silicon dioxide, silicate glass, or combinations thereof. The present invention also relates to a method of packaging a microelectronic device, including: providing a microelectronic device having a sensitive area; applying a water-insoluble, protective coating to the sensitive area; providing a package; attaching the device to the package; electrically interconnecting the device to the package; and substantially removing the protective coating from the sensitive area.

High temperature corrosion-resistant protective coatings in stationary gas turbines

NASA Technical Reports Server (NTRS)

Gruenling, H. W.

1977-01-01

Methods currently used to deposit protective coatings in gas turbines are reviewed, and the structure of the respective coatings is examined. The corrosion behavior of such coatings is discussed on the basis of experimental data. General trends in the preparation of protective coatings are noted.

Solution Coating of Pharmaceutical Nanothin Films and Multilayer Nanocomposites with Controlled Morphology and Polymorphism.

PubMed

Horstman, Elizabeth M; Kafle, Prapti; Zhang, Fengjiao; Zhang, Yifu; Kenis, Paul J A; Diao, Ying

2018-03-28

Nanosizing is rapidly emerging as an alternative approach to enhance solubility and thus the bioavailability of poorly aqueous soluble active pharmaceutical ingredients (APIs). Although numerous techniques have been developed to perform nanosizing of API crystals, precise control and modulation of their size in an energy and material efficient manner remains challenging. In this study, we present meniscus-guided solution coating as a new technique to produce pharmaceutical thin films of nanoscale thickness with controlled morphology. We demonstrate control of aspirin film thickness over more than 2 orders of magnitude, from 30 nm to 1.5 μm. By varying simple process parameters such as the coating speed and the solution concentration, the aspirin film morphology can also be modulated by accessing different coating regimes, namely the evaporation regime and the Landau-Levich regime. Using ellipticine-a poorly water-soluble anticancer drug-as another model compound, we discovered a new polymorph kinetically trapped during solution coating. Furthermore, the polymorphic outcome can be controlled by varying coating conditions. We further performed layer-by-layer coating of multilayer nanocomposites, with alternating thin films of ellipticine and a biocompatible polymer, which demonstrate the potential of additive manufacturing of multidrug-personalized dosage forms using this approach.

Photocatalytic degradation of an azo textile dye (C.I. Reactive Red 195 (3BF)) in aqueous solution over copper cobaltite nanocomposite coated on glass by Doctor Blade method.

PubMed

Habibi, Mohammad Hossein; Rezvani, Zoya

2015-08-05

The degradation of C.I. Reactive Red 195 (3BF) in aqueous solution using copper cobaltite nanocomposite coated on glass by Doctor Blade method was studied. Structural, optical and morphological properties of nanocomposite coatings were characterized by X-ray powder diffractometry (XRD), diffuse reflectance spectroscopy (DRS) and field emission scanning electron microscopy (FESEM). The nanoparticles exhibit a particle size of 31 nm, showing a good nanoscale crystalline morphology. The photocatalytic activity of copper cobaltite nanocomposite coated on glass was studied by performing the photocatalytic degradation of 3BF at different irradiation time. The effect of irradiation time on the degradation of 3BF was studied and the results showed that more than 85% of the 3BF was degraded in 45 min of irradiation. The pseudo-first-order kinetic models were used and the rate constants were evaluated with pseudo first order rate constants of 4.10 × 10(-2) min(-1). The main advantage of the photocatalyst coated on glass overcomes the difficulties in separation and recycle of photocatalyst suspensions. Copyright © 2015 Elsevier B.V. All rights reserved.

Photocatalytic degradation of an azo textile dye (C.I. Reactive Red 195 (3BF)) in aqueous solution over copper cobaltite nanocomposite coated on glass by Doctor Blade method

NASA Astrophysics Data System (ADS)

Habibi, Mohammad Hossein; Rezvani, Zoya

2015-08-01

The degradation of C.I. Reactive Red 195 (3BF) in aqueous solution using copper cobaltite nanocomposite coated on glass by Doctor Blade method was studied. Structural, optical and morphological properties of nanocomposite coatings were characterized by X-ray powder diffractometry (XRD), diffuse reflectance spectroscopy (DRS) and field emission scanning electron microscopy (FESEM). The nanoparticles exhibit a particle size of 31 nm, showing a good nanoscale crystalline morphology. The photocatalytic activity of copper cobaltite nanocomposite coated on glass was studied by performing the photocatalytic degradation of 3BF at different irradiation time. The effect of irradiation time on the degradation of 3BF was studied and the results showed that more than 85% of the 3BF was degraded in 45 min of irradiation. The pseudo-first-order kinetic models were used and the rate constants were evaluated with pseudo first order rate constants of 4.10 × 10-2 min-1. The main advantage of the photocatalyst coated on glass overcomes the difficulties in separation and recycle of photocatalyst suspensions.

Assessment of Thermal Control and Protective Coatings

NASA Technical Reports Server (NTRS)

Mell, Richard J.

2000-01-01

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

Evaluation of several corrosion protective coating systems on aluminum

NASA Technical Reports Server (NTRS)

Higgins, R. H.

1981-01-01

A study of several protective coating systems for use on aluminum in seawater/seacoast environments was conducted to review the developments made on protective coatings since early in the Space Shuttle program and to perform comparative studies on these coatings to determine their effectiveness for providing corrosion protection during exposure to seawater/seacoast environments. Panels of 2219-T87 aluminum were coated with 21 different systems and exposed to a 5 percent salt spray for 4000 hr. Application properties, adhesion measurements, heat resistance and corrosion protection were evaluated. For comparative studies, the presently specified Bostik epoxy system used on the SRB structures was included. Results of these tests indicate four systems with outstanding performance and four additional systems with protection almost as good. These systems are based on a chromated pretreatment, a chromate epoxy primer, and a polyurethane topcoat. Consideration for one of these systems should be included for those applications where superior corrosion protection for aluminum surfaces is required.

Nanoparticle/Polymer Nanocomposite Bond Coat or Coating

NASA Technical Reports Server (NTRS)

Miller, Sandi G.

2011-01-01

This innovation addresses the problem of coatings (meant to reduce gas permeation) applied to polymer matrix composites spalling off in service due to incompatibility with the polymer matrix. A bond coat/coating has been created that uses chemically functionalized nanoparticles (either clay or graphene) to create a barrier film that bonds well to the matrix resin, and provides an outstanding barrier to gas permeation. There is interest in applying clay nanoparticles as a coating/bond coat to a polymer matrix composite. Often, nanoclays are chemically functionalized with an organic compound intended to facilitate dispersion of the clay in a matrix. That organic modifier generally degrades at the processing temperature of many high-temperature polymers, rendering the clay useless as a nano-additive to high-temperature polymers. However, this innovation includes the use of organic compounds compatible with hightemperature polymer matrix, and is suitable for nanoclay functionalization, the preparation of that clay into a coating/bondcoat for high-temperature polymers, the use of the clay as a coating for composites that do not have a hightemperature requirement, and a comparable approach to the preparation of graphene coatings/bond coats for polymer matrix composites.

Solid particle erosion mechanisms of protective coatings for aerospace applications

NASA Astrophysics Data System (ADS)

Bousser, Etienne

The main objective of this PhD project is to investigate the material loss mechanisms during Solid Particle Erosion (SPE) of hard protective coatings, including nanocomposite and nanostructured systems. In addition, because of the complex nature of SPE mechanisms, rigorous testing methodologies need to be employed and the effects of all testing parameters need to be fully understood. In this PhD project, the importance of testing methodology is addressed throughout in order to effectively study the SPE mechanisms of brittle materials and coatings. In the initial stage of this thesis, we studied the effect of the addition of silicon (Si) on the microstructure, mechanical properties and, more specifically, on the SPE resistance of thick CrN-based coatings. It was found that the addition of Si significantly improved the erosion resistance and that SPE correlated with the microhardness values, i.e. the coating with the highest microhardness also had the lowest erosion rate (ER). In fact, the ERs showed a much higher dependence on the surface hardness than what has been proposed for brittle erosion mechanisms. In the first article, we study the effects of the particle properties on the SPE behavior of six brittle bulk materials using glass and alumina powders. First, we apply a robust methodology to accurately characterize the elasto-plastic and fracture properties of the studied materials. We then correlate the measured ER to materials' parameters with the help of a morphological study and an analysis of the quasi-static elasto-plastic erosion models. Finally, in order to understand the effects of impact on the particles themselves and to support the energy dissipation-based model proposed here, we study the particle size distributions of the powders before and after erosion testing. It is shown that tests using both powders lead to a material loss mechanism related to lateral fracture, that the higher than predicted velocity exponents point towards a velocity

Molybdate Coatings for Protecting Aluminum Against Corrosion

NASA Technical Reports Server (NTRS)

Calle, Luz Marina; MacDowell, Louis G.

2005-01-01

Conversion coatings that comprise mixtures of molybdates and several additives have been subjected to a variety of tests to evaluate their effectiveness in protecting aluminum and alloys of aluminum against corrosion. Molybdate conversion coatings are under consideration as replacements for chromate conversion coatings, which have been used for more than 70 years. The chromate coatings are highly effective in protecting aluminum and its alloys against corrosion but are also toxic and carcinogenic. Hexavalent molybdenum and, hence, molybdates containing hexavalent molybdenum, have received attention recently as replacements for chromates because molybdates mimic chromates in a variety of applications but exhibit significantly lower toxicity. The tests were performed on six proprietary formulations of molybdate conversion coatings, denoted formulations A through F, on panels of aluminum alloy 2024-T3. A bare alloy panel was also included in the tests. The tests included electrochemical impedance spectroscopy (EIS), measurements of corrosion potentials, scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), and x-ray photoelectron spectroscopy (XPS).

Protection of alodine coatings from thermal aging by removable polymer coatings.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wagstaff, Brett R.; Bradshaw, Robert W.; Whinnery, LeRoy L., Jr.

2006-12-01

Removable polymer coatings were evaluated as a means to suppress dehydration of Alodine chromate conversion coatings during thermal aging and thereby retain the corrosion protection afforded by Alodine. Two types of polymer coatings were applied to Alodine-treated panels of aluminum alloys 7075-T73 and 6061-T6 that were subsequently aged for 15 to 50 hours at temperatures between 135 F to 200 F. The corrosion resistance of the thermally aged panels was evaluated, after stripping the polymer coatings, by exposure to a standard salt-fog corrosion test and the extent of pitting of the polymer-coated and untreated panels compared. Removable polymer coatings mitigatedmore » the loss of corrosion resistance due to thermal aging experienced by the untreated alloys. An epoxide coating was more effective than a fluorosilicone coating as a dehydration barrier.« less

Electron-Beam Irradiation Effect on Thermal and Mechanical Properties of Nylon-6 Nanocomposite Fibers Infused with Diamond and Diamond Coated Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Imam, Muhammad A.; Jeelani, Shaik; Rangari, Vijaya K.; Gome, Michelle G.; Moura, Esperidiana. A. B.

2016-02-01

Nylon-6 is an engineering plastic with excellent properties and processability, which are essential in several industrial applications. The addition of filler such as diamond (DN) and diamond coated carbon nanotubes (CNTs) to form molded composites may increase the range of Nylon-6 applications due to the resulting increase in strength. The effects of electron-beam irradiation on these thermoplastic nanocomposites are either increase in the cross-linking or causes chain scission. In this study, DN-coated CNTs were synthesized using the sonochemical technique in the presence of cationic surfactant cetyltrimethyl ammonium bromide (CTAB). The DN-coated CNTs nanoparticles and diamond nanoparticles were then introduced into Nylon-6 polymer through a melt extrusion process to form nanocomposite fibers. They were further tested for their mechanical (Tensile) and thermal properties (thermogravimetric analysis (TGA), differential scanning calorimetry (DSC)). These composites were further exposed to the electron-beam (160kGy, 132kGy and 99kGy) irradiation using a 1.5MeV electron-beam accelerator, at room temperature, in the presence of air and tested for their thermal and mechanical properties. The best ultimate tensile strength was found to be 690MPa and 864MPa irradiated at 132 for DN/CNTs/Nylon-6 and Diamond/Nylon-6 nanocomposite fiber as compared to 346MPa and 321MPa for DN/CNTs/Nylon-6 and Diamond/Nylon-6 nanocomposite fiber without irradiation. The neat Nylon-6 tensile strength was 240MPa. These results are consistent with the activation energy calculated from TGA graphs. DSC analysis result shows that the slight increase in glass transition temperature (Tg) and decrease in melting temperature (Tm) which was expected from high electron-beam radiation dose.

Accelerated Test Method for Corrosion Protective Coatings Project

NASA Technical Reports Server (NTRS)

Falker, John; Zeitlin, Nancy; Calle, Luz

2015-01-01

This project seeks to develop a new accelerated corrosion test method that predicts the long-term corrosion protection performance of spaceport structure coatings as accurately and reliably as current long-term atmospheric exposure tests. This new accelerated test method will shorten the time needed to evaluate the corrosion protection performance of coatings for NASA's critical ground support structures. Lifetime prediction for spaceport structure coatings has a 5-year qualification cycle using atmospheric exposure. Current accelerated corrosion tests often provide false positives and negatives for coating performance, do not correlate to atmospheric corrosion exposure results, and do not correlate with atmospheric exposure timescales for lifetime prediction.

Fabrication and physical properties of transparent poly (methyl-methacrylate)-layered silicate nanocomposites

NASA Astrophysics Data System (ADS)

Vasiliu, Elena

Transparent polymer nanocomposites have promising potential for protective coating applications with improved surface resistance, higher temperature performance and low gas permeability for containers and films. Extremely thin protective layers are required for improved performance of various electronic devices in aviation, aerospace and medical equipment as well as for lenses and fiber optics in optical communications. This research study developed a method for fabricating optically transparent nanocomposites of poly(methyl-methacrylate)(PMMA) and a commercial organically-modified layered silicate CloisiteRTM 6A (C6A). The nanocomposites were produced by dispersing C6A and PMMA separately in a common solvent xylene followed by mixing the two solutions by mechanical stirring and/or ultrasonic agitation and then removing the solvent by evaporation. Processing conditions such as the mixing methods and times and the rates of solvent removal were investigated in order to achieve a high degree of dispersion and exfoliation of C6A in the polymer matrix and produce a nanocomposite material with high optical transparency. Small-angle x-ray scattering (SAXS) was used to monitor the morphology of the C6A after each processing step. Thin films of PMMA/C6A nanocomposites were produced by casting and spraying. SAXS results suggest that C6A was partially exfoliated in the composite material with an average of 2 to 3 platelets per crystallite. Transmission electron microscopy (TEM) confirmed the existence of both exfoliated and intercalated C6A in PMMA. One mm thick discs were obtained by molding the sprayed films. The optical transmission of the nanocomposite films and discs was measured with an UV/VIS spectrometer. The spectroscopic results served to identify the best process for producing PMMA-C6A films of high optical transparency. Even the nanocomposite films containing up to 20 wt.% C6A prepared by this process exhibited optical transmittance in the range of 80 to 90

Influence of Silver-hydroxyapatite Nanocomposite Coating on Biofilm Formation of Joint Prosthesis and Its Mechanism.

PubMed

Zhao, L; Ashraf, M A

2015-12-01

The main reason for biomaterial related refractory infections is biofilm formation caused by bacterial adhesion on the surface of materials. Silver-hydroxyapatite (Ag/HA) nanocomposite coating can inhibit the formation of biofilm, but its mechanism is not clear. In order to clarify the mechanism, the amounts of biofilm on the Ag/HA composite coating and HA coating were determined, the release rates of silver nanoparticles in simulated body fluid (SBF) were detected by atomic absorption spectrometry, and the expression values of atlE , fbe , sap , iapB genes of Staphylococcus aureus were studied when they grew on Ag/HA composite coating and HA coating. The amount of the biofilm on the Ag/HA composite coating was significantly less than that on the HA coating, and the bacterial adhesion was decreased. The silver nanoparticles were released continuously in SBF and the release rate decreased gradually with time. The expression values of atlE , fbe and sap were high in the initial stage of adhesion and the expression value of iapB was high in the colonies-gathering stage in the control group, but they were all significantly inhibited in the presence of Ag. These results indicated that the main antibacterial effect of Ag/HA composite coating was achieved by the release of silver nanoparticles. The addition of Ag inhibited the expression of genes related to biofilm formation, which in turn inhibited the formation of biofilms. This provided theoretical support for the clinical application of Ag/HA composite coating.

Enhanced antibacterial activity and biocompatibility of zinc-incorporated organic-inorganic nanocomposite coatings via electrophoretic deposition.

PubMed

Huang, Pin; Ma, Kena; Cai, Xinjie; Huang, Dan; Yang, Xu; Ran, Jiabing; Wang, Fushi; Jiang, Tao

2017-12-01

Increased use of reconstruction procedures in orthopedics has improved the life of patients undergoing surgery. However, surgical site infection remains a major challenge. Efforts were made to fabricate antibacterial surfaces with good biocompatibility. This present study aimed to fabricate zinc-incorporated chitosan/gelatin (CS/G) nanocomposite coatings on the titanium substrates via electrophoretic deposition (EPD). Physicochemical characterization confirmed that zinc was successfully deposited in a metallic oxide/salt complex status. Transmission electron microscopic (TEM) results observed formation of core-shell nanosized particles released from the coatings. The selected-area electron diffraction (SAED) pattern of the particles presented faces of ZnO with organic background. Mechanical tests showed improved tensile and shear bond strength between substrates and zinc-incorporated coating surfaces. Zinc-incorporated CS/G coatings presented antibacterial abilities against both Gram-negative E. coli and Gram-positive S. aureus in a concentration-dependent manner. The generation of ZnO/Zn 2+ complex in the coatings may contribute to bacteria inhibition. In vitro study demonstrated that appropriate concentration of zinc could promote proliferative and osteogenic activities of rat bone marrow stromal cells. The present study suggested that zinc-incorporated CS/G coating was a promising candidate for surface modification of biomedical materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Diffusional aspects of the high-temperature oxidation of protective coatings

NASA Technical Reports Server (NTRS)

Nesbitt, J. A.

1989-01-01

The role of diffusional transport associated with the high-temperature oxidation of coatings is examined, with special attention given to the low-pressure plasma spraying MCrAl-type overlay coatings and similar Ni-base alloys which form protective AlO3 scales. The use of diffusional analysis to predict the minimum solute concentration necessary to form and grow a solute oxide scale is illustrated. Modeling procedures designed to simulate the diffusional transport in coatings and substrates are presented to show their use in understanding coating degradation, predicting the protective life of a coating, and evaluating various coating parameters to guide coating development.

Investigation of anti-corrosive properties of poly(aniline-co-2-pyridylamine-co-2,3-xylidine) and its nanocomposite poly(aniline-co-2-pyridylamine-co-2,3-xylidine)/ZnO on mild steel in 0.1 M HCl

NASA Astrophysics Data System (ADS)

Alam, Ruman; Mobin, Mohammad; Aslam, Jeenat

2016-04-01

A soluble terpolymer of aniline (AN), 2-pyridylamine (PA) and 2,3-xylidine (XY), poly(AN-co-PA-co-XY) and its nanocomposite with ZnO nanoparticles namely, poly(AN-co-PA-co-XY)/ZnO were synthesized by chemical oxidative polymerization employing ammonium persulfate as an oxidant. Nanocomposites of homopolymers, polyaniline/ZnO, poly(XY)/ZnO and poly(PA)/ZnO were also synthesized by following similar synthesis route. FTIR, XRD and SEM techniques were used to characterize the synthesized compounds. The synthesized compounds were chemically deposited on mild steel specimens by solvent evaporation method using N-methyl-2-pyrrolidone (NMP) as solvent and 10% epoxy resin (by weight) as binder. Anticorrosive properties of homopolymer nanocomposites, terpolymer and its nanocomposite coatings were studied in 0.1 M HCl by subjecting them to various corrosion tests which includes: free corrosion potential measurement (OCP), weight loss measurements, potentiodynamic polarization, and AC impedance technique. The surface morphology of the corroded and uncorroded coated steel specimens was evaluated using SEM. The corrosion protection performance of terpolymer nanocomposite coating was compared to the terpolymer and individual homopolymers nanocomposites coatings after 30 days immersion in corrosive medium.

Effects of Si content on microstructure and mechanical properties of TiAlN/Si3N4-Cu nanocomposite coatings

NASA Astrophysics Data System (ADS)

Feng, Changjie; Hu, Shuilian; Jiang, Yuanfei; Wu, Namei; Li, Mingsheng; Xin, Li; Zhu, Shenglong; Wang, Fuhui

2014-11-01

TiAlN/Si3N4-Cu nanocomposite coatings of various Si content (0-5.09 at.%) were deposited on AISI-304 stainless steel by DC reactive magnetron sputtering technique. The chemical composition, microstructure, mechanical and tribological properties of these coatings were systematically investigated by means of X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), nanoindentation tester, a home-made indentation system, a scratch tester and a wear tester. Results indicated that with increasing Si content in these coatings, a reduction of grain size and surface roughness, a transformation of the (1 1 1) preferred orientation was detected by XRD and FESEM. Furthermore the hardness of these coatings increase from 9.672 GPa to 18.628 GPa, and the elastic modulus reveal the rising trend that increase from 224.654 GPa to 251.933 GPa. However, the elastic modulus of TiAlN/Si3N4-Cu coating containing 3.39 at.% Si content dropped rapidly and changed to about 180.775 GPa. The H3/E2 ratio is proportional to the film resistance to plastic deformation. The H3/E2 ratio of the TiAlN/Si3N4-Cu coating containing 3.39 at.% Si content possess of the maximum of 0.11 GPa, and the indentation test indicate that few and fine cracks were observed from its indentation morphologies. The growth pattern of cracks is mainly bending growing. The present results show that the best toughness is obtained for TiAlN/Si3N4-Cu nanocomposite coating containing 3.39 at.% Si content. In addition, the TiAlN/Si3N4-Cu coating containing 3.39 at.% Si content also has good adhesion property and superior wear resistance, and the wear mechanism is mainly adhesion wear.

Silicon-slurry/aluminide coating. [protecting gas turbine engine vanes and blades

NASA Technical Reports Server (NTRS)

Deadmore, D. L.; Young, S. G. (Inventor)

1983-01-01

A low cost coating protects metallic base system substrates from high temperatures, high gas velocity ovidation, thermal fatigue and hot corrosion and is particularly useful fo protecting vanes and blades in aircraft and land based gas turbine engines. A lacquer slurry comprising cellulose nitrate containing high purity silicon powder is sprayed onto the superalloy substrates. The silicon layer is then aluminized to complete the coating. The Si-Al coating is less costly to produce than advanced aluminides and protects the substrates from oxidation and thermal fatigue for a much longer period of time than the conventional aluminide coatings. While more expensive Pt-Al coatings and physical vapor deposited MCrAlY coatings may last longer or provide equal protection on certain substrates, the Si-Al coating exceeded the performance of both types of coatings on certain superalloys in high gas velocity oxidation and thermal fatigue and increased the resistance of certain superalloys to hot corrosion.

Method of protecting a surface with a silicon-slurry/aluminide coating. [coatings for gas turbine engine blades and vanes

NASA Technical Reports Server (NTRS)

Deadmore, D. L.; Young, S. G. (Inventor)

1982-01-01

A low cost coating for protecting metallic base system substrates from high temperatures, high gas velocity oxidation, thermal fatigue and hot corrosion is described. The coating is particularly useful for protecting vanes and blades in aircraft and land based gas turbine engines. A lacquer slurry comprising cellulose nitrate containing high purity silicon powder is sprayed onto the superalloy substrates. The silicon layer is then aluminized to complete the coating. The Si-Al coating is less costly to produce than advanced aluminides and protects the substrate from oxidation and thermal fatigue for a much longer period of time than the conventional aluminide coatings. While more expensive Pt-Al coatings and physical vapor deposited MCrAlY coatings may last longer or provide equal protection on certain substrates, the Si-Al coating exceeded the performance of both types of coatings on certain superalloys in high gas velocity oxidation and thermal fatigue. Also, the Si-Al coating increased the resistance of certain superalloys to hot corrosion.

Investigation of Corrosion Protection in Oil Mineral Reservoirs by Nanocomposites Used as Coating Layers

NASA Astrophysics Data System (ADS)

Al-Sarraf, Abdulhameed R.; Al-Saaidi, Samer A.

2018-05-01

In this study, a number of nanocomposites were prepared by adding magnesium oxide (MgO) with weight percentages (1, 2 & 3)% to cellulose nitrate and sodium silicate as an intermediate layer and other nanocomposites by adding MgO, coal coke and hybrid (MgO & coal coke with ratio 1:1) with weight percentages (1, 2 & 3)% to epoxy resin as final layer. The identity of the used metal is determined by spectrometer OE thermo. The nature and topography of the surface layers were examined by optical microscope and atomic force microscope (AFM). Mechanical properties are indicated by hardness, wear rate, impact strength and adhesion strength. The efficiency of the layers prepared to inhibit corrosion in the oil mineral reservoirs of the oil products distribution company was studied by electrochemical corrosion test in addition to the chemical corrosion test. The used metal is (St-37) according to (ASTM). It was found that the best intermediate layer (cellulose nitrate+3%MgO) and the final layer is the epoxy resin reinforced by 2% hybrid.

Next-Generation Magnetic Nanocomposites: Cytotoxic and Genotoxic Effects of Coated and Uncoated Ferric Cobalt Boron (FeCoB) Nanoparticles In Vitro.

PubMed

Netzer, Katharina; Jordakieva, Galateja; Girard, Angelika M; Budinsky, Alexandra C; Pilger, Alexander; Richter, Lukas; Kataeva, Nadezhda; Schotter, Joerg; Godnic-Cvar, Jasminka; Ertl, Peter

2018-03-01

Metal nanoparticles (NPs) have unique physicochemical properties and a widespread application scope depending on their composition and surface characteristics. Potential biomedical applications and the growing diversity of novel nanocomposites highlight the need for toxicological hazard assessment of next-generation magnetic nanomaterials. Our study aimed to evaluate the cytotoxic and genotoxic properties of coated and uncoated ferric cobalt boron (FeCoB) NPs (5-15 nm particle size) in cultured normal human dermal fibroblasts. Cell proliferation was assessed via ATP bioluminescence kit, and DNA breakage and chromosomal damage were measured by alkaline comet assay and micronucleus test. Polyacryl acid-coated FeCoB NPs [polyacrylic acid (PAA)-FeCoB NPs) and uncoated FeCoB NPs inhibited cell proliferation at 10 μg/ml. DNA strand breaks were significantly increased by PAA-coated FeCoB NPs, uncoated FeCoB NPs and l-cysteine-coated FeCoB NPs (Cys-FeCoB NPs), although high concentrations (10 μg/ml) of coated NPs (Cys- and PAA-FeCoB NPs) showed significantly more DNA breakage when compared to uncoated ones. Uncoated FeCoB NPs and coated NPs (PAA-FeCoB NPs) also induced the formation of micronuclei. Additionally, PAA-coated NPs and uncoated FeCoB NPs showed a negative correlation between cell proliferation and DNA strand breaks, suggesting a common pathomechanism, possibly by oxidation-induced DNA damage. We conclude that uncoated FeCoB NPs are cytotoxic and genotoxic at in vitro conditions. Surface coating of FeCoB NPs with Cys and PAA does not prevent but rather aggravates DNA damage. Further safety assessment and a well-considered choice of surface coating are needed prior to application of FeCoB nanocomposites in biomedicine. © 2017 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

Production and characterization of a novel carbon nanotube/titanium nitride nanocomposite

NASA Astrophysics Data System (ADS)

Baddour, Carole Emilie; Das, Kaushik; Vengallatore, Srikar; Meunier, Jean-Luc

2016-12-01

A novel titanium nitride (TiN)/carbon nanotube (CNT) nanocomposite is produced with the purpose to mechanically, structurally and chemically stabilize a ‘felt-like’ CNT growth structure. The CNTs are grown on stainless steel (SS) 304 by chemical vapor deposition using the direct growth method previously developed, which does not require the use of an additional catalyst precursor. The TiN coating is achieved by physical vapor deposition and is shown here to generate a nanocomposite with a porous three-dimensional architecture. The contact stiffness is evaluated using nanoindentation, and wetting properties of the TiN/CNT nanocomposites are determined from contact angle measurements. An increase in contact stiffness and effective elastic modulus with TiN coating time was observed. The TiN coating on the non-wetting CNT felt results in a wetting nanocomposite surface. The wetting property is found to be a function of the TiN coating thickness on the CNT structure.

Protective coating for alumina-silicon carbide whisker composites

DOEpatents

Tiegs, Terry N.

1989-01-01

Ceramic composites formed of an alumina matrix reinforced with silicon carbide whiskers homogenously dispersed therein are provided with a protective coating for preventing fracture strength degradation of the composite by oxidation during exposure to high temperatures in oxygen-containing atmospheres. The coating prevents oxidation of the silicon carbide whiskers within the matrix by sealing off the exterior of the matrix so as to prevent oxygen transport into the interior of the matrix. The coating is formed of mullite or mullite plus silicon oxide and alumina and is formed in place by heating the composite in air to a temperature greater than 1200.degree. C. This coating is less than about 100 microns thick and adequately protects the underlying composite from fracture strength degradation due to oxidation.

Influence of Silver-hydroxyapatite Nanocomposite Coating on Biofilm Formation of Joint Prosthesis and Its Mechanism

PubMed Central

Zhao, L; Ashraf, MA

2015-01-01

ABSTRACT Background: The main reason for biomaterial related refractory infections is biofilm formation caused by bacterial adhesion on the surface of materials. Silver-hydroxyapatite (Ag/HA) nanocomposite coating can inhibit the formation of biofilm, but its mechanism is not clear. Material and Method: In order to clarify the mechanism, the amounts of biofilm on the Ag/HA composite coating and HA coating were determined, the release rates of silver nanoparticles in simulated body fluid (SBF) were detected by atomic absorption spectrometry, and the expression values of atlE, fbe, sap, iapB genes of Staphylococcus aureus were studied when they grew on Ag/HA composite coating and HA coating. Results: The amount of the biofilm on the Ag/HA composite coating was significantly less than that on the HA coating, and the bacterial adhesion was decreased. The silver nanoparticles were released continuously in SBF and the release rate decreased gradually with time. The expression values of atlE, fbe and sap were high in the initial stage of adhesion and the expression value of iapB was high in the colonies-gathering stage in the control group, but they were all significantly inhibited in the presence of Ag. Conclusion: These results indicated that the main antibacterial effect of Ag/HA composite coating was achieved by the release of silver nanoparticles. The addition of Ag inhibited the expression of genes related to biofilm formation, which in turn inhibited the formation of biofilms. This provided theoretical support for the clinical application of Ag/HA composite coating. PMID:27400164

Characterization and in vitro biocompatibility study of Ti-Si-N nanocomposite coatings developed by using physical vapor deposition

NASA Astrophysics Data System (ADS)

Trivedi, Pramanshu; gupta, Pallavi; Srivastava, Swati; Jayaganthan, R.; Chandra, Ramesh; Roy, Partha

2014-02-01

Amongst the Ti alloys used as orthopedic implant materials, Ti6Al4V is one of the widely used alloys. Magnetron sputtering was used to deposit nanocomposite coating of Ti-Si-N on the Ti6Al4V substrate at different power and then the coating structure and surface properties were characterized through contact angle measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). In vitro biocompatibility of the coatings was assessed by using mouse bone marrow mesenchymal stem cells (mBMMSC). Antibacterial studies were performed using Escherichia coli (E. coli) microorganisms. The osteogenic differentiation was also carried out in order to get gene expressions. The AFM results confirmed that the coatings deposited at 120 W was smoother as compared to other coatings developed at different power, along with optimum contact angle, also these coatings showed good antibacterial results. The fluorescent and viability results of 120 W sample confirmed their good biocompatibility as compared to the coatings deposited 20, 40, 60, and 100 W power. Hence, the coating deposited at 120 W exhibit desirable microstructural characteristics beneficial for surface modification of orthopedic implants.

Injection Molding and Mechanical Properties of Bio-Based Polymer Nanocomposites.

PubMed

Mistretta, Maria Chiara; Botta, Luigi; Morreale, Marco; Rifici, Sebastiano; Ceraulo, Manuela; La Mantia, Francesco Paolo

2018-04-17

The use of biodegradable/bio-based polymers is of great importance in addressing several issues related to environmental protection, public health, and new, stricter legislation. Yet some applications require improved properties (such as barrier or mechanical properties), suggesting the use of nanosized fillers in order to obtain bio-based polymer nanocomposites. In this work, bionanocomposites based on two different biodegradable polymers (coming from the Bioflex and MaterBi families) and two different nanosized fillers (organo-modified clay and hydrophobic-coated precipitated calcium carbonate) were prepared and compared with traditional nanocomposites with high-density polyethylene (HDPE) as matrix. In particular, the injection molding processability, as well as the mechanical and rheological properties of the so-obtained bionanocomposites were investigated. It was found that the processability of the two biodegradable polymers and the related nanocomposites can be compared to that of the HDPE-based systems and that, in general, the bio-based systems can be taken into account as suitable alternatives.

Injection Molding and Mechanical Properties of Bio-Based Polymer Nanocomposites

PubMed Central

Mistretta, Maria Chiara; Rifici, Sebastiano; Ceraulo, Manuela

2018-01-01

The use of biodegradable/bio-based polymers is of great importance in addressing several issues related to environmental protection, public health, and new, stricter legislation. Yet some applications require improved properties (such as barrier or mechanical properties), suggesting the use of nanosized fillers in order to obtain bio-based polymer nanocomposites. In this work, bionanocomposites based on two different biodegradable polymers (coming from the Bioflex and MaterBi families) and two different nanosized fillers (organo-modified clay and hydrophobic-coated precipitated calcium carbonate) were prepared and compared with traditional nanocomposites with high-density polyethylene (HDPE) as matrix. In particular, the injection molding processability, as well as the mechanical and rheological properties of the so-obtained bionanocomposites were investigated. It was found that the processability of the two biodegradable polymers and the related nanocomposites can be compared to that of the HDPE-based systems and that, in general, the bio-based systems can be taken into account as suitable alternatives. PMID:29673143

Molybdenum protective coatings adhesion to steel substrate

NASA Astrophysics Data System (ADS)

Blesman, A. I.; Postnikov, D. V.; Polonyankin, D. A.; Teplouhov, A. A.; Tyukin, A. V.; Tkachenko, E. A.

2017-06-01

Protection of the critical parts, components and assemblies from corrosion is an urgent engineering problem and many other industries. Protective coatings’ forming on surface of metal products is a promising way of corrosionprevention. The adhesion force is one of the main characteristics of coatings’ durability. The paper presents theoretical and experimental adhesion force assessment for coatings formed by molybdenum magnetron sputtering ontoa steel substrate. Validity and reliability of results obtained by simulation and sclerometry method allow applying the developed model for adhesion force evaluation in binary «steel-coating» systems.

Preparation of Tween 80-Zn/Al-Levodopa-Layered Double Hydroxides Nanocomposite for Drug Delivery System

PubMed Central

Kura, Aminu Umar; Hussein-Al-Ali, Samer Hasan; Hussein, Mohd Zobir; Fakurazi, Sharida

2014-01-01

We incorporated anti-Parkinsonian drug, levodopa (dopa), in Zn/Al-LDH by coprecipitation method to form dopa-LDH nanocomposite. Further coating of Tween-80 on the external surfaces of dopa-LDH nanocomposite was achieved through the oxygen of C=O group of Tween-80 with the layer of dopa-LDH nanocomposite. The final product is called Tween-dopa-LDH nanocomposite. The X-ray diffraction indicates that the Tween-dopa-LDH nanocomposite was formed by aggregation structure. From the TGA data, the Tween-80 loading on the surface of LDH and dopa-LDH was 8.6 and 7.4%, respectively. The effect of coating process on the dopa release from Tween-dopa-LDH nanocomposite was also studied. The release from Tween-dopa-LDH nanocomposite shows slower release compared to the release of the drug from dopa-LDH nanocomposite as done previously in our study, presumably due to the retarding shielding effect. The cell viability study using PC12 showed improved viability with Tween-80 coating on dopa-LDH nanocomposite as studied by mitochondrial dehydrogenase activity (MTT assay). PMID:24782658

Protection of moisture-sensitive drugs with aqueous polymer coatings: importance of coating and curing conditions.

PubMed

Bley, O; Siepmann, J; Bodmeier, R

2009-08-13

The aim of this study was to better understand the importance of coating and curing conditions of moisture-protective polymer coatings. Tablets containing freeze-dried garlic powder were coated with aqueous solutions/dispersions of hydroxypropyl methylcellulose (HPMC), poly(vinyl alcohol), ethyl cellulose and poly(methacrylate-methylmethacrylates). The water content of the tablets during coating and during storage at different temperatures and relative humidities (RH) was determined gravimetrically. In addition, changes in the allicin (active ingredient in garlic powder) content were monitored. During the coating process, the water uptake was below 2.7% and no drug degradation was detectable. Thermally induced drug degradation occurred only at temperatures above the coating temperatures. Different polymer coatings effectively decreased the rate, but not the extent of water uptake during open storage at room temperature and 75% RH. Tablets coated with poly(vinyl alcohol) and poly(methacrylate-methylmethacrylates) showed the lowest moisture uptake rates (0.49 and 0.57%/d, respectively). Curing at elevated temperature after coating did not improve the moisture-protective ability of the polymeric films, but reduced the water content of the tablets. Drug stability was significantly improved with tablets coated with poly(vinyl alcohol) and poly(methacrylate-methylmethacrylates).

Tuning silver ion release properties in reactively sputtered Ag/TiOx nanocomposites

NASA Astrophysics Data System (ADS)

Xiong, J.; Ghori, M. Z.; Henkel, B.; Strunskus, T.; Schürmann, U.; Deng, M.; Kienle, L.; Faupel, F.

2017-07-01

Silver/titania nanocomposites with strong bactericidal effects and good biocompatibility/environmental safety show a high potential for antibacterial applications. Tailoring the silver ion release is thus highly promising to optimize the antibacterial properties of such coatings and to preserve biocompatibility. Reactive sputtering is a fast and versatile method for the preparation of such Ag/TiOx nanocomposites coatings. The present work is concerned with the influence of sputter parameters on the surface morphology and silver ion release properties of reactively sputtered Ag/TiOx nanocomposites coatings showing a silver nanoparticle size distribution in the range from 1 to 20 nm. It is shown that the silver ion release rate strongly depends on the total pressure: the coatings prepared at lower pressure present a lower but long-lasting release behavior. The much denser structure produced under these conditions reduces the transport of water molecules into the coating. In addition, the influence of microstructure and thickness of titanium oxide barriers on the silver ion release were investigated intensively. Moreover, for the coatings prepared at high total pressure, it was demonstrated that stable and long-lasting silver release can be achieved by depositing a barrier with a high rate. Nanocomposites produced under these conditions show well controllable silver ion release properties for applications as antibacterial coatings.

Performance of nanocomposites for preservation of artistic stones

NASA Astrophysics Data System (ADS)

Giancristofaro, Cristina; D'Amato, Rosaria; Caneve, Luisa; Pilloni, Luciano; Rinaldi, Antonio; Persia, Franca

2014-06-01

In this work, the effectiveness of nanocomposite surface treatments as protective systems for artistic stones was evaluated. Pyrolitic silica and titania nanoparticles were dispersed in a commercial silicon-based polymer and applied on marble and travertine samples. Artificial aging processes, both in climatic chamber and in solar box, were carried out to simulate real degradation processes in terms of photo-thermal effects and physical-chemical damage. The performances of the nanocomposites used as consolidant were evaluated comparatively by means of diverse diagnostic techniques, namely: scanning electron microscopy (SEM), laser induced fluorescence (LIF), ultrasonic technique, colorimetry, total immersion water absorption and contact angle. The results show that some properties of conservation materials can be improved by the presences of nanoparticles because they induce substantial changes of surface morphology of the coating layer and counter the physical damage observed during artificial weathering.

Sputtered protective coatings for die casting dies

NASA Technical Reports Server (NTRS)

Mirtich, M. J.; Nieh, C.-Y.; Wallace, J. F.

1981-01-01

Three experimental research designs investigating candidate materials and processes involved in protective die surface coating procedures by sputter deposition, using ion beam technologies, are discussed. Various pre-test results show that none of the coatings remained completely intact for 15,000 test cycles. The longest lifetime was observed for coatings such as tungsten, platinum, and molybdenum which reduced thermal fatigue, but exhibited oxidation and suppressed crack initiation only as long as the coating did not fracture. Final test results confirmed earlier findings and coatings with Pt and W proved to be the candidate materials to be used on a die surface to increase die life. In the W-coated specimens, which remained intact on the surface after thermal fatigue testing, no oxidation was found under the coating, although a few cracks formed on the surface where the coating broke down. Further research is planned.

In situ diazonium-modified flexible ITO-coated PEN substrates for the deposition of adherent silver-polypyrrole nanocomposite films.

PubMed

Samanta, Soumen; Bakas, Idriss; Singh, Ajay; Aswal, Dinesh K; Chehimi, Mohamed M

2014-08-12

In this paper, we report a simple and versatile process of electrografting the aryl multilayers onto indium tin oxide (ITO)-coated flexible poly(ethylene naphthalate) (PEN) substrates using a diazonium salt (4-pyrrolylphenyldiazonium) solution, which was generated in situ from a reaction between the 4-(1H-pyrrol-1-yl)aniline precursor and sodium nitrite in an acidic medium. The first aryl layer bonds with the ITO surface through In-O-C and Sn-O-C bonds which facilitate the formation of a uniform aryl multilayer that is ∼8 nm thick. The presence of the aryl multilayer has been confirmed by impedance spectroscopy as well as by electron-transfer blocking measurements. These in situ diazonium-modified ITO-coated PEN substrates may find applications in flexible organic electronics and sensor industries. Here we demonstrate the application of diazonium-modified flexible substrates for the growth of adherent silver/polpyrrole nanocomposite films using surface-confined UV photopolymerization. These nanocomposite films have platelet morphology owing to the template effect of the pyrrole-terminated aryl multilayers. In addition, the films are highly doped (32%). This work opens new areas in the design of flexible ITO-conductive polymer hybrids.

Chemical conversion coating for protecting magnesium alloys from corrosion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhargava, Gaurang; Allen, Fred M.; Skandan, Ganesh

A chromate-free, self-healing conversion coating solution for magnesium alloy substrates, composed of 10-20 wt. % Mg(NO.sub.3).sub.2.6H.sub.2O, 1-5 wt. % Al(NO.sub.3).sub.3.9H.sub.2O, and less than 1 wt. % of [V.sub.10O.sub.28].sup.6- or VO.sub.3.sup.- dissolved in water. The corrosion resistance offered by the resulting coating is in several hundreds of hours in salt-spray testing. This prolonged corrosion protection is attributed to the creation of a unique structure and morphology of the conversion coating that serves as a barrier coating with self-healing properties. Hydroxoaluminates form the backbone of the barrier protection offered while the magnesium hydroxide domains facilitate the "slow release" of vanadium compounds asmore » self-healing moieties to defect sites, thus providing active corrosion protection.« less

Silver-doped nanocomposite carbon coatings (Ag-DLC) for biomedical applications - Physiochemical and biological evaluation

NASA Astrophysics Data System (ADS)

Bociaga, Dorota; Komorowski, Piotr; Batory, Damian; Szymanski, Witold; Olejnik, Anna; Jastrzebski, Krzysztof; Jakubowski, Witold

2015-11-01

The formation of bacteria biofilm on the surface of medical products is a major clinical issue nowadays. Highly adaptive ability of bacteria to colonize the surface of biomaterials causes a lot of infections. This study evaluates samples of the AISI 316 LVM with special nanocomposite silver-doped (by means of ion implantation) diamond-like carbon (DLC) coating prepared by hybrid RF/MS PACVD (radio frequency/magnetron sputtering plasma assisted chemical vapour deposition) deposition technique in order to improve the physicochemical and biological properties of biomaterials and add new features such as antibacterial properties. The aim of the following work was to evaluate antimicrobial efficacy and biocompatibility of gradient a-C:H/Ti + Ag coatings in relation to the physiochemical properties of the surface and chemical composition of coating. For this purpose, samples were tested in live/dead test using two cell strains: human endothelial cells (Ea.hy926) and osteoblasts-like cells (Saos-2). For testing bactericidal activity of the coatings, an exponential growth phase of Escherichia coli strain DH5α was used as a model microorganism. Surface condition and its physicochemical properties were investigated using SEM, AFM and XPS. Examined coatings showed a uniformity of silver ions distribution in the amorphous DLC matrix, good biocompatibility in contact with mammalian cells and an increased level of bactericidal properties. What is more, considering very good mechanical parameters of these Ag including gradient a-C:H/Ti coatings, they constitute an excellent material for biomedical application in e.g. orthopedics or dentistry.

Sprayable Phase Change Coating Thermal Protection Material

NASA Technical Reports Server (NTRS)

Richardson, Rod W.; Hayes, Paul W.; Kaul, Raj

2005-01-01

NASA has expressed a need for reusable, environmentally friendly, phase change coating that is capable of withstanding the heat loads that have historically required an ablative thermal insulation. The Space Shuttle Program currently relies on ablative materials for thermal protection. The problem with an ablative insulation is that, by design, the material ablates away, in fulfilling its function of cooling the underlying substrate, thus preventing the insulation from being reused from flight to flight. The present generation of environmentally friendly, sprayable, ablative thermal insulation (MCC-l); currently use on the Space Shuttle SRBs, is very close to being a reusable insulation system. In actual flight conditions, as confirmed by the post-flight inspections of the SRBs, very little of the material ablates. Multi-flight thermal insulation use has not been qualified for the Space Shuttle. The gap that would have to be overcome in order to implement a reusable Phase Change Coating (PCC) is not unmanageable. PCC could be applied robotically with a spray process utilizing phase change material as filler to yield material of even higher strength and reliability as compared to MCC-1. The PCC filled coatings have also demonstrated potential as cryogenic thermal coatings. In experimental thermal tests, a thin application of PCC has provided the same thermal protection as a much thicker and heavier application of a traditional ablative thermal insulation. In addition, tests have shown that the structural integrity of the coating has been maintained and phase change performance after several aero-thermal cycles was not affected. Experimental tests have also shown that, unlike traditional ablative thermal insulations, PCC would not require an environmental seal coat, which has historically been required to prevent moisture absorption by the thermal insulation, prevent environmental degradation, and to improve the optical and aerodynamic properties. In order to reduce

Tests Of Protective Coats For Carbon Steel

NASA Technical Reports Server (NTRS)

Macdowell, Louis G., III

1995-01-01

Report describes laboratory and field tests of candidate paints (primers, tie coats, and topcoats) for use in protecting carbon-steel structures against corrosion in seaside environment at Kennedy Space Center. Coating materials selected because of utility in preventing corrosion, also on basis of legal requirements, imposed in several urban areas, for reduction of volatile organic contents.

Multispectral Coatings

DTIC Science & Technology

2010-01-01

failure, whereas the polymer nanocomposite gave ductile failure with less surface damage. Task 2. Highly reflective self-assembled coatings . The...AFRL-RX-WP-TR-2010-4036 MULTISPECTRAL COATINGS Eric Grulke University of Kentucky Thad Druffel Optical Dynamics JANUARY...REPORT TYPE 3. DATES COVERED (From - To) January 2010 Final 28 November 2005 – 30 September 2008 4. TITLE AND SUBTITLE MULTISPECTRAL COATINGS 5a

Polymeric coating of surface modified nitinol stent with POSS-nanocomposite polymer.

PubMed

Bakhshi, Raheleh; Darbyshire, Arnold; Evans, James Eaton; You, Zhong; Lu, Jian; Seifalian, Alexander M

2011-08-01

Stent angioplasty is a successful treatment for arterial occlusion, particularly in coronary artery disease. The clinical communities were enthusiastic about the use of drug-eluting stents; however, these stents have a tendency to be a contributory factor towards late stage thrombosis, leading to mortality in a significant number of patients per year. This work presents an innovative approach in self-expanding coronary stents preparation. We developed a new nanocomposite polymer based on polyhedral oligomeric silsesquioxanes (POSS) and poly(carbonate-urea)urethane (PCU), which is an antithrombogenic and a non-biodegradable polymer with in situ endothelialization properties. The aim of this work is to coat a NiTi stent alloy with POSS-PCU. In prolonged applications in the human body, the corrosion of the NiTi alloy can result in the release of deleterious ions which leads to unwanted biological reactions. Coating the nitinol (NiTi) surface with POSS-PCU can enhance surface resistance and improve biocompatibility. Electrohydrodynamic spraying was used as the polymer deposition process and thus a few experiments were carried out to compare this process with casting. Prior to deposition the NiTi has been surface modified. The peel strength of the deposit was studied before and after degradation of the coating. It is shown that the surface modification enhances the peel strength by 300%. It is also indicated how the adhesion strength of the POSS-PCU coating changes post-exposure to physiological solutions comprised of hydrolytic, oxidative, peroxidative and biological media. This part of the study shows that the modified NiTi presents far greater resistance to decay in peel strength compared to the non-modified NiTi. Copyright © 2011 Elsevier B.V. All rights reserved.

Improved Dielectric Properties and Energy Storage Density of Poly(vinylidene fluoride-co-hexafluoropropylene) Nanocomposite with Hydantoin Epoxy Resin Coated BaTiO3.

PubMed

Luo, Hang; Zhang, Dou; Jiang, Chao; Yuan, Xi; Chen, Chao; Zhou, Kechao

2015-04-22

Energy storage materials are urgently demanded in modern electric power supply and renewable energy systems. The introduction of inorganic fillers to polymer matrix represents a promising avenue for the development of high energy density storage materials, which combines the high dielectric constant of inorganic fillers with supernal dielectric strength of polymer matrix. However, agglomeration and phase separation of inorganic fillers in the polymer matrix remain the key barriers to promoting the practical applications of the composites for energy storage. Here, we developed a low-cost and environmentally friendly route to modifying BaTiO3 (BT) nanoparticles by a kind of water-soluble hydantoin epoxy resin. The modified BT nanoparticles exhibited homogeneous dispersion in the ferroelectric polymer poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) matrix and strong interfacial adhesion with the polymer matrix. The dielectric constants of the nanocomposites increased significantly with the increase of the coated BT loading, while the dielectric loss of the nanocomposites was still as low as that of the pure P(VDF-HFP). The energy storage density of the nanocomposites was largely enhanced with the coated BT loading at the same electric field. The nanocomposite with 20 vol % BT exhibited an estimated maximum energy density of 8.13 J cm(-3), which was much higher than that of pure P(VDF-HFP) and other dielectric polymers. The findings of this research could provide a feasible approach to produce high energy density materials for practical application in energy storage.

New method for evaluating high-quality fog protective coatings

NASA Astrophysics Data System (ADS)

Czeremuszkin, Grzegorz; Latreche, Mohamed; Mendoza-Suarez, Guillermo

2011-05-01

Fogging is commonly observed when humid-warm air contacts the cold surface of a transparent substrate, i.e. eyewear lenses, making the observed image blurred and hazy. To protect from fogging, the lens inner surfaces are protected with Anti-Fog coatings, which render them hydrophilic and induce water vapor condensation as a smooth, thin and invisible film, which uniformly flows down on the lens as the condensation progresses. Coatings differ in protection level, aging kinetics, and susceptibility to contamination. Some perform acceptably in limited conditions, beyond which the condensing water film becomes unstable, nonuniform, and scatters light or shows refractory distortions, both affecting the observed image. Quantifying the performance of Anti-Fog coated lenses is difficult: they may not show classical fogging and the existing testing methods, based on fog detection, are therefore inapplicable. The presented method for evaluating and quantifying AF properties is based on characterizing light scattering on lenses exposed to controlled humidity and temperature. Changes in intensity of laser light scattered at low angles (1, 2 4 and 8 degrees), observed during condensation of water on lenses, provide information on the swelling of Anti-Fog coatings, formation of uniform water film, going from an unstable to a steady state, and on the coalescence of discontinuous films. Real time observations/measurements allow for better understanding of factors controlling fogging and fog preventing phenomena. The method is especially useful in the development of new coatings for military-, sport-, and industrial protective eyewear as well as for medical and automotive applications. It allows for differentiating between coatings showing acceptable, good, and excellent performance.

49 CFR 192.461 - External corrosion control: Protective coating.

Code of Federal Regulations, 2012 CFR

2012-10-01

... protective coating, whether conductive or insulating, applied for the purpose of external corrosion control... or damage from supporting blocks. (e) If coated pipe is installed by boring, driving, or other...

49 CFR 192.461 - External corrosion control: Protective coating.

Code of Federal Regulations, 2014 CFR

2014-10-01

... protective coating, whether conductive or insulating, applied for the purpose of external corrosion control... or damage from supporting blocks. (e) If coated pipe is installed by boring, driving, or other...

Formation of protective composite coatings with the use of SPTFE suspensions

NASA Astrophysics Data System (ADS)

Nadaraia, K. V.; Mashtalyar, D. V.; Sinebryukhov, S. L.; Gnedenkov, S. V.

2017-09-01

The method of protective composite coatings formation with the use of the plasma electrolytic oxidation (PEO) and subsequent treatment in isopropanol or aqueous suspension of the superdispersed polytetrafluoroethylene (SPTFE) have been developed. Morphological, electrochemical and tribological studies, as well as wetting ability of the protective coatings have been carried out. The obtained results corroborated the increase of the corrosion and wear resistance parameters for the polymer-containing coating in comparison with the base PEO-coating and uncoated material.

Performance of nanocomposites for preservation of artistic stones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giancristofaro, Cristina; Pilloni, Luciano; Rinaldi, Antonio

2014-06-19

In this work, the effectiveness of nanocomposite surface treatments as protective systems for artistic stones was evaluated. Pyrolitic silica and titania nanoparticles were dispersed in a commercial silicon-based polymer and applied on marble and travertine samples. Artificial aging processes, both in climatic chamber and in solar box, were carried out to simulate real degradation processes in terms of photo-thermal effects and physical-chemical damage. The performances of the nanocomposites used as consolidant were evaluated comparatively by means of diverse diagnostic techniques, namely: scanning electron microscopy (SEM), laser induced fluorescence (LIF), ultrasonic technique, colorimetry, total immersion water absorption and contact angle. Themore » results show that some properties of conservation materials can be improved by the presences of nanoparticles because they induce substantial changes of surface morphology of the coating layer and counter the physical damage observed during artificial weathering.« less

Nanocomposite vacuum-Arc TiC/a-C:H coatings prepared using an additional ionization of acetylene

NASA Astrophysics Data System (ADS)

Trakhtenberg, I. Sh.; Gavrilov, N. V.; Emlin, D. R.; Plotnikov, S. A.; Vladimirov, A. B.; Volkova, E. G.; Rubshtein, A. P.

2014-07-01

The composition, structure, and properties of TiC/a-C:H coatings obtained by simultaneous vacuum-arc deposition of titanium and carbon in a low-pressure argon-acetylene medium additionally activated by a low-energy (a few hundreds of electron-volts) electron beam. The creation of conditions under which the decomposition of acetylene is provided by the ionization and dissociation of molecules due to electron impacts and by the recharging of molecules through titanium and argon ions with subsequent dissociation should favor the most complete decomposition of acetylene in a wide range of pressures. With increasing acetylene pressure, the structure of the nanocomposite coating changes: the size of TiC crystallites decreases, and the fraction of interfaces (or the fraction of regions with a disordered (amorphous) structure) increases. The application of a bias voltage leads to an increase in the sizes of TiC nanocrystallites. The coatings with a maximum microhardness (˜40 GPa) have been obtained without the action of an electron beam under an acetylene pressure of ˜0.05-0.08 Pa and the atomic ratio Ti: C ˜ 0.9: 1.1 in the coating.

Clay-based nanocomposite coating for flexible optoelectronics applying commercial polymers.

PubMed

Kunz, Daniel A; Schmid, Jasmin; Feicht, Patrick; Erath, Johann; Fery, Andreas; Breu, Josef

2013-05-28

Transparency, flexibility, and especially ultralow oxygen (OTR) and water vapor (WVTR) transmission rates are the key issues to be addressed for packaging of flexible organic photovoltaics and organic light-emitting diodes. Concomitant optimization of all essential features is still a big challenge. Here we present a thin (1.5 μm), highly transparent, and at the same time flexible nanocomposite coating with an exceptionally low OTR and WVTR (1.0 × 10(-2) cm(3) m(-2) day(-1) bar(-1) and <0.05 g m(-2) day(-1) at 50% RH, respectively). A commercially available polyurethane (Desmodur N 3600 and Desmophen 670 BA, Bayer MaterialScience AG) was filled with a delaminated synthetic layered silicate exhibiting huge aspect ratios of about 25,000. Functional films were prepared by simple doctor-blading a suspension of the matrix and the organophilized clay. This preparation procedure is technically benign, is easy to scale up, and may readily be applied for encapsulation of sensitive flexible electronics.

Anti-Adhesion Elastomer Seal Coatings for Ultraviolet and Atomic Oxygen Protection

NASA Technical Reports Server (NTRS)

De Groh, Henry C., III; Puleo, Bernadette J.; Waters, Deborah L.; Miller, Sharon K.

2015-01-01

Radiation blocking sunscreen coatings have been developed for the protection of elastomer seals used in low-Earth-orbit (LEO). The coatings protect the seals from ultraviolet (UV) radiation and atomic oxygen (AO) damage. The coatings were developed for use on NASA docking seals. Docking seal damage from the UV and AO present in LEO can constrain mission time-line, flight mode options, and increases risk. A low level of adhesion is also required for docking seals so undocking push-off forces can be low. The coatings presented also mitigate this unwanted adhesion. Greases with low collected volatile condensable materials (CVCM) and low total mass loss (TML) were mixed with slippery and/or UV blocking powders to create the protective coatings. Coatings were applied at rates up to 2 milligrams per square centimeter. Coated seals were exposed to AO and UV in the NUV (near-UV) and UV-C wavelength ranges (300 to 400 nanometers and 254 nanometers, respectively). Ground based ashers were used to simulate the AO of space. The Sun's UV energy was mimicked assuming a nose forward flight mode, resulting in an exposure rate of 2.5 megajoules per square meter per day. Exposures between 0 and 147 megajoules per square meter (UV-C) and 245 megajoules per square meter (NUV) were accomplished. The protective coatings were durable, providing protection from UV after a simulated docking and undocking cycle. The level of protection begins to decline at coverage rates less than 0.9 milligrams per square centimeter. The leakage of seals coated with Braycote plus 20 percent Z-cote ZnO sunscreen increased by a factor of 40 after moderate AO exposure; indicating that this coating might not be suitable due to AO intolerance. Seals coated with DC-7-16.4 percent Z-cote ZnO sunscreen were not significantly affected by combined doses of 2 x 10 (sup 21) atoms per square AO with 73 megajoules per square meter UV-C. Unprotected seals were significantly damaged at UV-C exposures of 0.3 megajoules per

Development of Protective Coatings for Co-Sequestration Processes and Pipelines

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 asmore » potential candidates for internal pipeline coating to transport SCCO2.« less

Iridium Aluminide Coats For Protection Against Ox idation

NASA Technical Reports Server (NTRS)

Kaplan, Richard B.; Tuffias, Robert H.; La Ferla, Raffaele; Jang, Qin

1996-01-01

Iridium aluminide coats investigated for use in protecting some metallic substrates against oxidation at high temperatures. Investigation prompted by need for cost-effective anti-oxidation coats for walls of combustion chambers in rocket engines. Also useful in special terrestrial applications like laboratory combustion chambers and some chemical-processing chambers.

Mesoporous carbon-zirconium oxide nanocomposite derived from carbonized metal organic framework: A coating for solid-phase microextraction.

PubMed

Saraji, Mohammad; Mehrafza, Narges

2016-08-19

In this paper, a mesoporous carbon-ZrO2 nanocomposite was fabricated on a stainless steel wire for the first time and used as the solid-phase microextraction coating. The fiber was synthesized with the direct carbonization of a Zr-based metal organic framework. With the utilization of the metal organic framework as the precursor, no additional carbon source was used for the synthesis of the mesoporous carbon-ZrO2 nanocomposite coating. The fiber was applied for the determination of BTEX compounds (benzene, toluene, ethylbenzene and m, p-xylenes) in different water samples prior to gas chromatography-flame ionization detection. Such important experimental factors as synthesis time and temperature, salt concentration, equilibrium and extraction time, extraction temperature, desorption time and desorption temperature were studied and optimized. Good linearity in the concentration range of 0.2-200μgL(-1) and detection limits in the range of 0.05-0.56μgL(-1) was achieved for BTEX compounds. The intra- and inter-day relative standard deviations were in the range of 3.5-4.8% and 4.9-6.7%, respectively. The prepared fiber showed high capability for the analysis of BTEX compounds in different water and wastewater samples with good relative recoveries in the range of 93-107%. Copyright © 2016 Elsevier B.V. All rights reserved.

Organic matrix composite protective coatings for space applications

NASA Technical Reports Server (NTRS)

Dursch, Harry W.; George, Pete

1995-01-01

Successful use of composites in low earth orbit (LEO) depends on their ability to survive long-term exposure to atomic oxygen (AO), ultraviolet radiation, charged particle radiation, thermal cycling, and micrometeoroid and space debris. The AO environment is especially severe for unprotected organic matrix composites surfaces in LEO. Ram facing unprotected graphite/epoxy flown on the 69-month Long Duration Exposure Facility (LDEF) mission lost up to one ply of thickness (5 mils) resulting in decreased mechanical properties. The expected AO fluence of the 30 year Space Station Alpha mission is approximately 20 times that seen on LDEF. This exposure would result in significant material loss of unprotected ram facing organic matrix composites. Several protective coatings for composites were flown on LDEF including anodized aluminum, vacuum deposited coatings, a variety of thermal control coatings, metalized Teflon, and leafing aluminum. Results from the testing and analysis of the coated and uncoated composite specimens flown on LDEF's leading and trailing edges provide the baseline for determining the effectiveness of protectively coated composites in LEO. In addition to LDEF results, results from shuttle flight experiments and ground based testing will be discussed.

Development of novel nano-composite membranes as introduction systems for mass spectrometers: Contrasting nano-composite membranes and conventional inlet systems

NASA Astrophysics Data System (ADS)

Miranda, Luis Diego

This dissertation presents the development of novel nano-composite membranes as introduction systems for mass spectrometers. These nano-composite membranes incorporate anodic aluminum oxide (AAO) membranes as templates that can be used by themselves or modified by a variety of chemical deposition processes. Two types of nano-composite membranes are presented. The first nano-composite membrane has carbon deposited within the pores of an AAO membrane. The second nano-composite membrane is made by coating an AAO membrane with a thin polymer film. The following chapters describe the transmission properties these nano-composite membranes and compare them to conventional mass spectrometry introduction systems. The nano- composite membranes were finally coupled to the inlet system of an underwater mass spectrometer revealing their utility in field deployments.

Phase Stability and Thermal Conductivity of Composite Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Benkel, Samantha; Zhu, Dongming

2011-01-01

Advanced environmental barrier coatings are being developed to protect SiC/SiC ceramic matrix composites in harsh combustion environments. The current coating development emphasis has been placed on the significantly improved cyclic durability and combustion environment stability in high-heat-flux and high velocity gas turbine engine environments. Environmental barrier coating systems based on hafnia (HfO2) and ytterbium silicate, HfO2-Si nano-composite bond coat systems have been processed and their stability and thermal conductivity behavior have been evaluated in simulated turbine environments. The incorporation of Silicon Carbide Nanotubes (SiCNT) into high stability (HfO2) and/or HfO2-silicon composite bond coats, along with ZrO2, HfO2 and rare earth silicate composite top coat systems, showed promise as excellent environmental barriers to protect the SiC/SiC ceramic matrix composites.

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

NASA Technical Reports Server (NTRS)

Merutka, J. P.

1981-01-01

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

A green single-step procedure to synthesize Ag-containing nanocomposite coatings with low cytotoxicity and efficient antibacterial properties

PubMed Central

Ma, Kena; Gong, Lingling; Cai, Xinjie; Huang, Pin; Cai, Jing; Huang, Dan; Jiang, Tao

2017-01-01

Implant-associated infections still pose a serious threat leading to several complications. This study reported an environmentally benign Ag-containing nanocomposite coating with efficient antibacterial property fabricated on the metal implant via electrophoretic deposition (EPD). In such coatings, Ag2O/AgCl mixed with chitosan/gelatin (CS/G) polymers work together to exert the antibacterial property which could act as an alternative to traditional Ag nanoparticles. Scanning electron microscopy images showed the shuttle fiber-like morphology distributed lamellarly and some nanoparticles carved uniformly into the cross section. Transmission electron microscopy results revealed a core–shell-like structure of the released nanoparticles in experimental groups. The Ag-containing coatings exhibited strong antibacterial properties against Staphylococcus aureus strains and Escherichia coli strains. Meanwhile, the CCK-8 tests showed that after assembling with chitosan and gelatin polymers, the cytotoxicity of Ag was largely decreased. In addition, such coatings also exhibited strong bond strength with metal substrates and good degradable properties. Therefore, such Ag-containing CS/G coatings fabricated via EPD may be a promising candidate to be administrated in controlling the implant-associated infections. PMID:28553106

Improvement of the titanium implant biological properties by coating with poly (ε-caprolactone)-based hybrid nanocomposites synthesized via sol-gel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Catauro, Michelina; Bollino, Flavia; Papale, Ferdinando

When bioactive coatings are applied to medical implants by means of sol-gel dip coating technique, the biological proprieties of the implant surface can be modified to match the properties of the surrounding tissues. In this study organo-inorganic nanocomposites materials were synthesized via sol-gel. They consisted of an inorganic zirconium-based and silica-based matrix, in which a biodegradable polymer (the poly-ε-caprolactone, PCL) was incorporated in different weight percentages. The synthesized materials, in sol phase, were used to dip-coat a substrate of commercially pure titanium grade 4 (CP Ti gr. 4) in order to improve its biological properties. A microstructural analysis of themore » obtained films was carried out by scanning electron microscopy (SEM) and attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FT-IR). Biological proprieties of the coated substrates were investigated by means of in vitro tests.« less

Ca (OH)2Nanoparticles Based on Acrylic Copolymers for the consolidation and protection of Ancient Egypt Calcareous Stone Monuments

NASA Astrophysics Data System (ADS)

Al-Dosari, Mohammad A.; Darwish, Sawsan S.; Adam, Mahmoud A.; Elmarzugi, Nagib A.; Al-Mouallimi, Nadia; Ahmed, Sayed M.

2017-04-01

The deterioration of calcareous stones materials used in artistic/architectural field is one of the most serious problems facing conservation today. The aim of this study was to evaluate the effectiveness of nanosized particles of calcium hydroxide (slaked lime) as a consolidation and protection material dispersed in acrylic copolymer, poly ethylmethacrylate/methylacrylate (70:30) (Poly (EMA/MA), for calcareous stone monuments and painted surfaces affected by different kinds of decay. The synthesis process of Ca (OH)2 nanoparticles/polymer nanocomposites have been prepared by in situ emulsion polymerization system. The prepared nanocomposite containing 5% of Ca (OH)2 nanoparticles showed obvious transparency features and represent nanocomposites coating technology with hydrophobic, consolidating and well protection properties.

Protection of Advanced Copper Alloys With Lean Cu-Cr Coatings

NASA Technical Reports Server (NTRS)

Greenbauer-Seng, L. (Technical Monitor); Thomas-Ogbuji, L.

2003-01-01

Advanced copper alloys are used as liners of rocket thrusters and nozzle ramps to ensure dissipation of the high thermal load generated during launch, and Cr-lean coatings are preferred for the protection of these liners from the aggressive ambient environment. It is shown that adequate protection can be achieved with thin Cu-Cr coatings containing as little as 17 percent Cr.

Chitosan-based ultrathin films as antifouling, anticoagulant and antibacterial protective coatings.

PubMed

Bulwan, Maria; Wójcik, Kinga; Zapotoczny, Szczepan; Nowakowska, Maria

2012-01-01

Ultrathin antifouling and antibacterial protective nanocoatings were prepared from ionic derivatives of chitosan using layer-by-layer deposition methodology. The surfaces of silicon, and glass protected by these nanocoatings were resistant to non-specific adsorption of proteins disregarding their net charges at physiological conditions (positively charged TGF-β1 growth factor and negatively charged bovine serum albumin) as well as human plasma components. The coatings also preserved surfaces from the formation of bacterial (Staphylococcus aureus) biofilm as shown using microscopic studies (SEM, AFM) and the MTT viability test. Moreover, the chitosan-based films adsorbed onto glass surface demonstrated the anticoagulant activity towards the human blood. The antifouling and antibacterial actions of the coatings were correlated with their physicochemical properties. The studied biologically relevant properties were also found to be dependent on the thickness of those nanocoatings. These materials are promising for biomedical applications, e.g., as protective coatings for medical devices, anticoagulant coatings and protective layers in membranes.

Surface protection coating material for controlling the decay of major construction stone

NASA Astrophysics Data System (ADS)

Arun, T.; Ray, D. K.; Gupta, V. P.; Panda, S. S.; Sahoo, P. K.; Ghosh, Jaydip; Sengupta, Pranesh; Satyam, P. V.

2017-05-01

Degradation of the building stones are creating instability in the old building and monuments which is to be protected. To investigate the characteristics of such a stones used for the construction in eastern India, we have collected the khondalite stones. The microstructural and elemental composition analysis of the khondalite stones are analyzed by using SEM, EDX and PIXE trace elemental analysis. We have prepared surface protection coating material with graphene oxide and cobalt ferrite as a base material along with other residuals. The prepared coating materials is coated on the galvanized iron substrate for further characterization. The surface morphology characteristics of the coating material is analyzed by SEM and AFM. The corrosion resistance characteristics of the prepared coating material is studied by the electrochemical impedance spectroscopy. The results suggests that the prepared coating material can be used as a surface protection materials to control the self-destruction of khondalite stones.

Graphene coatings for protection against microbiologically induced corrosion

NASA Astrophysics Data System (ADS)

Krishnamurthy, Ajay

Microbiologically induced corrosion (MIC) is a special form of electrochemical corrosion where micro-organisms affect the local environmental conditions at the metal-electrolyte interface by forming a stable biofilm. The biofilm introduces localized concentration cells, which accelerate the electrochemical corrosion rates. MIC has been found to affect many industrial systems such as sewage waste water pipes, heat exchangers, ships, underwater pipes etc. It has been traditionally eradicated by physical, biochemical and surface protection methods. The cleaning methods and the biocidal deliveries are required periodically and don't provide a permanent solution to the problem. Further, the use of biocides has been harshly criticized by environmentalists due to safety concerns associated with their usage. Surface based coatings have their own drawback of rapid degradation under harsh microbial environments. This has led to the exploration of thin, robust, inert, conformal passivation coatings for the protection of metallic surfaces from microbiologically induced corrosion. Graphene is a 2D arrangement of carbon atoms in a hexagonal honeycomb lattice. The carbon atoms are bonded to one another by sp2 hybridization and each layer of the carbon ring arrangement spans to a thickness of less than a nm. Due to its unique 2D arrangement of carbon atoms, graphene exhibits interesting in-plane and out of plane properties that have led to it being considered as the material for the future. Its excellent thermal, mechanical, electrical and optical properties are being explored in great depth to understand and realize potential applications in various technological realms. Early studies have shown the ability of bulk and monolayer graphene to protect metallic surfaces from air oxidation and solution based galvanic corrosion processes for short periods. However, the role of graphene in resisting MIC is yet to be determined, particularly over the long time spans characteristic of

Renewal of corrosion protection of coated aluminum after welding

NASA Technical Reports Server (NTRS)

Higgins, R. H.

1969-01-01

Effectiveness of conversion coatings designed to protect aluminum alloys against atmospheric corrosion is reduced after exposure to high temperature or welding. Damaged coating should be manually stripped six inches from the weld and then recoated by sponge or spray with the original solution.

Sputtered coatings for protection of spacecraft polymers

NASA Technical Reports Server (NTRS)

Banks, B. A.; Mirtich, M. J.; Rutledge, S. K.; Swec, D. M.

1983-01-01

Kapton polyimide oxidizes at significant rates (4.3x10(-24) gram/incident oxygen atom) when exposed in low Earth orbit to the ram atomic oxygen flux. Ion beam sputter deposited thin films of Al2O3 and SiO2 as well as a codeposited mixture of predominantly SiO2 with a small amount of polytetrafluoroethylene were evaluated and found to be effective in protecting Kapton from oxidation in both laboratory plasma ashing tests as well as in space on board shuttle flight STS-8. A protective film of or = 96 percent SiO2 and or = 4 percent polytetrafluoroethylene was found to be very flexible compared to the pure metal oxide coatings and resulted in mass loss rates that were 0.2 percent of that of the unprotected Kapton. The optical properties of Kapton for wavelengths investigated between 0.33 and 2.2 microns were not significantly altered by the presence of the coatings or changed by exposure of the coated Kapton to the low Earth orbital ram environment.

Methods of making non-covalently bonded carbon-titania nanocomposite thin films and applications of the same

DOEpatents

Liang, Yu Teng; Vijayan, Baiju K.; Gray, Kimberly A.; Hersam, Mark C.

2016-07-19

In one aspect, a method of making non-covalently bonded carbon-titania nanocomposite thin films includes: forming a carbon-based ink; forming a titania (TiO.sub.2) solution; blade-coating a mechanical mixture of the carbon-based ink and the titania solution onto a substrate; and annealing the blade-coated substrate at a first temperature for a first period of time to obtain the carbon-based titania nanocomposite thin films. In certain embodiments, the carbon-based titania nanocomposite thin films may include solvent-exfoliated graphene titania (SEG-TiO.sub.2) nanocomposite thin films, or single walled carbon nanotube titania (SWCNT-TiO.sub.2) nanocomposite thin films.

Quantification of nanoparticle release from polymer nanocomposite coatings due to environmental stressing.

PubMed

Kim, Yeon Seok; Davis, Rick; Uddin, Nasir; Nyden, Marc; Rabb, Savelas A

2016-01-01

Certain engineered nanoparticles (ENP) reduce the flammability of components used in soft furnishings (mattresses and upholstered furniture). However, because of the ENP's small size and ability to interact with biological molecules, these fire retardant ENPs may pose a health and environmental risks, if they are released sometime during the life cycle of the soft furnishing. Quantifying the released amount of these ENPs under normal end-use circumstances provides a basis for assessing their potential health and environmental impact. In this article, we report on efforts to identify suitable methodologies for quantifying the release of carbon nanofibers, carbon nanotubes, and sodium montmorillonites from coatings applied to the surfaces of barrier fabric and polyurethane foam. The ENPs released in simulated chewing and mechanical stressing experiments were collected in aqueous solution and quantified using Ultraviolet-Visible and inductively coupled plasma-optical emission spectroscopy. The microstructures of the released ENPs were characterized using scanning electron microscopy. The reported methodology and results provide important milestones to estimate the impact and toxicity of the ENP release during the life cycle of the nanocomposites. To our knowledge, this is the first study of ENP release from the soft furnishing coating, something that can be important application area for fire safety.

Effect of Novel Quercetin Titanium Dioxide-Decorated Multi-Walled Carbon Nanotubes Nanocomposite on Bacillus subtilis Biofilm Development

PubMed Central

Raie, Diana S.; Mhatre, Eisha; El-Desouki, Doaa S.; Labena, Ahmed; El-Ghannam, Gamal; Farahat, Laila A.; Youssef, Tareq; Fritzsche, Wolfgang; Kovács, Ákos T.

2018-01-01

The present work was targeted to design a surface against cell seeding and adhering of bacteria, Bacillus subtilis. A multi-walled carbon nanotube/titanium dioxide nano-power was produced via simple mixing of carbon nanotube and titanium dioxide nanoparticles during the sol-gel process followed by heat treatment. Successfully, quercetin was immobilized on the nanocomposite via physical adsorption to form a quercetin/multi-walled carbon nanotube/titanium dioxide nanocomposite. The adhesion of bacteria on the coated-slides was verified after 24 h using confocal laser-scanning microscopy. Results indicated that the quercetin/multi-walled carbon nanotube/titanium dioxide nanocomposite had more negativity and higher recovery by glass surfaces than its counterpart. Moreover, coating surfaces with the quercetin-modified nanocomposite lowered both hydrophilicity and surface-attached bacteria compared to surfaces coated with the multi-walled carbon nanotubes/titanium dioxide nanocomposite. PMID:29346268

Spray shadowing for stress relief and mechanical locking in thick protective coatings

DOEpatents

Hollis, Kendall [Los Alamos, NM; Bartram, Brian [Los Alamos, NM

2007-05-22

A method for applying a protective coating on an article, comprising the following steps: selecting an article with a surface for applying a coating thickness; creating undercut grooves on the article, where the grooves depend beneath the surface to a bottom portion with the grooves having an upper width on the surface and a lower width on the bottom portion connected by side walls, where at least one of the side walls connects the upper width and the lower width to form an undercut angle with the surface less than 90.degree.; and, applying the protective coating onto the article to fill the undercut grooves and cover the surface, thereby forming weak paths within the protective coating.

Thermal Protective Coating for High Temperature Polymer Composites

NASA Technical Reports Server (NTRS)

Barron, Andrew R.

1999-01-01

The central theme of this research is the application of carboxylate-alumoxane nanoparticles as precursors to thermally protective coatings for high temperature polymer composites. In addition, we will investigate the application of carboxylate-alumoxane nanoparticle as a component to polymer composites. The objective of this research was the high temperature protection of polymer composites via novel chemistry. The significance of this research is the development of a low cost and highly flexible synthetic methodology, with a compatible processing technique, for the fabrication of high temperature polymer composites. We proposed to accomplish this broad goal through the use of a class of ceramic precursor material, alumoxanes. Alumoxanes are nano-particles with a boehmite-like structure and an organic periphery. The technical goals of this program are to prepare and evaluate water soluble carboxylate-alumoxane for the preparation of ceramic coatings on polymer substrates. Our proposed approach is attractive since proof of concept has been demonstrated under the NRA 96-LeRC-1 Technology for Advanced High Temperature Gas Turbine Engines, HITEMP Program. For example, carbon and Kevlar(tm) fibers and matting have been successfully coated with ceramic thermally protective layers.

Method and coating composition for protecting and decontaminating surfaces

DOEpatents

Overhold, D C; Peterson, M D

1959-03-10

A protective coating useful in the decontamination of surfaces exposed to radioactive substances is described. This coating is placed on the surface before use and is soluble in water, allowing its easy removal in the event decontamination becomes necessary. Suitable coating compositions may be prepared by mixing a water soluble carbohydrate such as sucrose or dextrin, together with a hygroscopic agent such as calcium chloride or zinc chloride.

METHOD AND COATING COMPOSITION FOR PROTECTING AND DECONTAMINATING SURFACES

DOEpatents

Overhold, D.C.; Peterson, M.D.

1959-03-10

A protective coating useful in the decontamination of surfaces exposed to radioactive substances is presented. This coating is placed on the surface before use and is soluble in waters allowing its easy removal in the event decontamination becomes necessary. Suitable coating compositions may be prepared by mixing a water soluble carbohydrate such as sucrose or dextrin, together with a hygroscopic agent such as calcium chloride or zinc chloride.

Electrochemical detection of nitrite on poly(pyronin Y)/graphene nanocomposites modified ITO substrate

NASA Astrophysics Data System (ADS)

Şinoforoğlu, Mehmet; Dağcı, Kader; Alanyalıoğlu, Murat; Meral, Kadem

2016-06-01

The present study reports on an easy preparation of poly(pyronin Y)/graphene (poly(PyY)/graphene) nanocomposites thin films on indium tin oxide coated glass substrates (ITO). The thin films of poly(PyY)/graphene nanocomposites are prepared by a novel method consisting of three steps; (i) preparation of graphene oxide (GO) thin films on ITO by spin-coating method, (ii) self-assembly of PyY molecules from aqueous solution onto the GO thin film, (iii) surface-confined electropolymerization (SCEP) of the adsorbed PyY molecules on the GO thin film. The as-prepared poly(PyY)/graphene nanocomposites thin films are characterized by using electroanalytical and spectroscopic techniques. Afterwards, the graphene-based polymeric dye thin film on ITO is used as an electrode in an electrochemical cell. Its performance is tested for electrochemical detection of nitrite. Under optimized conditions, the electrocatalytical effect of the nanocomposites thin film through electrochemical oxidation of nitrite is better than that of GO coated ITO.

Silicon nitride protective coatings for silvered glass mirrors

DOEpatents

Tracy, C. Edwin; Benson, David K.

1988-01-01

A protective diffusion barrier for metalized mirror structures is provided by a layer or coating of silicon nitride which is a very dense, transparent, dielectric material that is impervious to water, alkali, and other impurities and corrosive substances that typically attack the metal layers of mirrors and cause degradation of the mirrors' reflectivity. The silicon nitride layer can be deposited on the substrate before metal deposition to stabilize the metal/substrate interface, and it can be deposited over the metal to encapsulate it and protect the metal from corrosion or other degradation. Mirrors coated with silicon nitride according to this invention can also be used as front surface mirrors.

Silicon nitride protective coatings for silvered glass mirrors

DOEpatents

Tracy, C.E.; Benson, D.K.

1984-07-20

A protective diffusion barrier for metalized mirror structures is provided by a layer or coating of silicon nitride which is a very dense, transparent, dielectric material that is impervious to water, alkali, and other impurities and corrosive substances that typically attack the metal layers of mirrors and cause degradation of the mirrors' reflectivity. The silicon nitride layer can be deposited on the substrate prior to metal deposition thereon to stabilize the metal/substrate interface, and it can be deposited over the metal to encapsulate it and protect the metal from corrosion or other degradation. Mirrors coated with silicon nitride according to this invention can also be used as front surface mirrors.

Fast dissolution of poorly water soluble drugs from fluidized bed coated nanocomposites: Impact of carrier size.

PubMed

Azad, Mohammad; Moreno, Jacqueline; Bilgili, Ecevit; Davé, Rajesh

2016-11-20

Formation of core-shell nanocomposites of Fenofibrate and Itraconazole, model poorly water soluble drugs, via fluidized bed (FB) coating of their well-stabilized high drug loaded nanosuspensions is investigated. Specifically, the extent of dissolution enhancement, when fine carrier particles (sub-50μm) as opposed to the traditional large carrier particles (>300μm) are used, is examined. This allows testing the hypothesis that greatly increased carrier surface area and more importantly, thinner shell for finer carriers at the same drug loading can significantly increase the dissolution rate when spray-coated nanosuspensions are well-stabilized. Fine sub-50μm lactose (GranuLac ® 200) carrier particles were made fluidizable via dry coating with nano-silica, enabling decreased cohesion, fluidization and subsequent nanosuspension coating. For both drugs, 30% drug loaded suspensions were prepared via wet-stirred media milling using hydroxypropyl methyl cellulose and sodium dodecyl sulfate as stabilizers. The stabilizer concentrations were varied to affect the milled particle size and prepare a stable nanosuspension. The suspensions were FB coated onto hydrophilic nano-silica (M-5P) dry coated sub-50μm lactose (GranuLac ® 200) carrier particles or larger carrier particles of median size >300μm (PrismaLac ® 40). The resulting finer composite powders (sub-100μm) based on GranuLac ® 200 were freely flowing, had high bulk density, and had much faster, immediate dissolution of the poorly water-soluble drugs, in particular for Itraconazole. This is attributed to a much higher specific surface area of the carrier and corresponding thinner coating layer for fine carriers as opposed to those for large carrier particles. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication and characterization of highly porous barium titanate based scaffold coated by Gel/HA nanocomposite with high piezoelectric coefficient for bone tissue engineering applications.

PubMed

Ehterami, Arian; Kazemi, Mansure; Nazari, Bahareh; Saraeian, Payam; Azami, Mahmoud

2018-03-01

It is well established that the piezoelectric effect plays an important physiological role in bone growth, remodeling and fracture healing. Barium titanate, as a well-known piezoelectric ceramic, is especially an attractive material as a scaffold for bone tissue engineering applications. In this regard, we tried to fabricate a highly porous barium titanate based scaffolds by foam replication method and polarize them by applying an external electric field. In order to enhance the mechanical and biological properties, polarized/non-polarized scaffolds were coated with gelatin and nanostructured HA and characterized for their morphologies, porosities, piezoelectric and mechanical properties. The results showed that the compressive strength and piezoelectric coefficient of porous scaffolds increased with the increase of sintering temperature. After being coated with Gel/HA nanocomposite, the interconnected porous structure and pore size of the scaffolds almost remain unchanged while the Gel/nHA-coated scaffolds exhibited enhanced compressive strength and elastic modulus compared with the uncoated samples. Also, the effect of polarizing and coating of optimal scaffolds on adhesion, viability, and proliferation of the MG63 osteoblast-like cell line was evaluated by scanning electron microscope (SEM) and MTT assay. The cell culture experiments revealed that developed scaffolds had good biocompatibility and cells were able to adhere, proliferate and migrate into pores of the scaffolds. Furthermore, cell density was significantly higher in the coated scaffolds at all tested time-points. These results indicated that highly porous barium titanate scaffolds coated with Gel/HA nanocomposite has great potential in tissue engineering applications for bone tissue repair and regeneration. Copyright © 2018 Elsevier Ltd. All rights reserved.

Field repair of coated columbium Thermal Protection System (TPS)

NASA Technical Reports Server (NTRS)

Culp, J. D.

1972-01-01

The requirements for field repair of coated columbian panels were studied, and the probable cause of damage were identified. The following types of repair methods were developed, and are ready for use on an operational system: replacement of fused slurrey silicide coating by a short processing cycle using a focused radiant spot heater; repair of the coating by a glassy matrix ceramic composition which is painted or sprayed over the defective area; and repair of the protective coating by plasma spraying molybdenum disilicide over the damaged area employing portable equipment.

Atomic Oxygen Durability Evaluation of a UV Curable Ceramer Protective Coating

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Karniotis, Christina A.; Dworak, David; Soucek, Mark

2004-01-01

The exposure of most silicones to atomic oxygen in low Earth orbit (LEO) results in the oxidative loss of methyl groups with a gradual conversion to oxides of silicon. Typically there is surface shrinkage of oxidized silicone protective coatings which leads to cracking of the partially oxidized brittle surface. Such cracks widen and branch crack with continued atomic oxygen exposure ultimately allowing atomic oxygen to reach any hydrocarbon polymers under the silicone coating. A need exists for a paintable silicone coating that is free from such surface cracking and can be effectively used for protection of polymers and composites in LEO. A new type of silicone based protective coating holding such potential was evaluated for atomic oxygen durability in an RF atomic oxygen plasma exposure facility. The coating consisted of a UV curable inorganic/organic hybrid coating, known as a ceramer, which was fabricated using a methyl substituted polysiloxane binder and nanophase silicon-oxo-clusters derived from sol-gel precursors. The polysiloxane was functionalized with a cycloaliphatic epoxide in order to be cured at ambient temperature via a cationic UV induced curing mechanism. Alkoxy silane groups were also grafted onto the polysiloxane chain, through hydrosilation, in order to form a network with the incorporated silicon-oxo-clusters. The prepared polymer was characterized by H-1 and Si-29 NMR, FT-IR, and electrospray ionization mass spectroscopy. The paper will present the results of atomic oxygen protection ability of thin ceramer coatings on Kapton H as evaluated over a range of atomic oxygen fluence levels.

Manipulation of ZnO composition affecting electrical properties of MEH-PPV: ZnO nanocomposite thin film via spin coating for OLEDs application

NASA Astrophysics Data System (ADS)

Azhar, N. E. A.; Shariffudin, S. S.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

Recent investigations of the promising materials for optoelectronic have been demonstrated by introducing n-type inorganic material into conjugated polymer. Morphology, optical and electrical of nanocomposites thin films based on poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and zinc oxide (ZnO) nanotetrapods with various ZnO composition (0 wt% to 0.4 wt%) have been investigated. The MEH-PPV: ZnO nanocomposite thin film was deposited using spin-coating method. Surface morphology was characterized using field emission scanning electron microscopy and shows the uniform dispersion of MEH-PPV and ZnO phases for sample deposited at 0.2 wt%. The photoluminescence (PL) spectra shows the visible emission intensities increased when the ZnO composition increased. The current-voltage (I-V) measurement shows the highest conductivity of nanocomposite thin film deposited at 0.2 wt% of ZnO is 7.40 × 10-1 S. cm-1. This study will provide better performance and suitable for optoelectronic device especially OLEDs application.

Influence of Food with High Moisture Content on Oxygen Barrier Property of Polyvinyl Alcohol (PVA)/Vermiculite Nanocomposite Coated Multilayer Packaging Film.

PubMed

Kim, Jung Min; Lee, Min Hyeock; Ko, Jung A; Kang, Dong Ho; Bae, Hojae; Park, Hyun Jin

2018-02-01

This study investigates the potential complications in applying nanoclay-based waterborne coating to packaging films for food with high moisture content. Multilayer packaging films were prepared by dry laminating commercially available polyvinyl alcohol (PVA)/vermiculite nanocomposite coating films and linear low-density polyethylene film, and the changes in oxygen barrier properties were investigated according to different relative humidity using 3 types of food simulants. When the relative humidity was above 60%, the oxygen permeability increased sharply, but this was reversible. Deionized water and 3% acetic acid did not cause any large structural change in the PVA/vermiculite nanocomposite but caused a reversible deterioration of the oxygen barrier properties. In contrast, 50% ethanol, a simulant for the semifatty food, induced irreversible structural changes with deterioration of the oxygen barrier property. These changes are due to the characteristics of PVA rather than vermiculite. We believe this manuscript would be of interest to the wide group of researchers, organizations, and companies in the field of developing nanoclay-based gas barrier packaging for foods with high moisture content. Hence, we wish to diffuse our knowledge to the scientific community. © 2018 Institute of Food Technologists®.

Protective Behavior of Poly(m-aminophenol) and Polypyrrole Coatings on Mild Steel

NASA Astrophysics Data System (ADS)

Yahaya, Sabrina M.; Harun, M. K.; Rosmamuhamadani, R.; Bonnia, N. N.; Ratim, S.

2018-01-01

Electrodeposition of polypyrrole (PPy) and poly (m-aminophenol) (PMAP) films on mild steel (MS) substrate was achieved in 0.3M oxalic acid solution and 0.3M NaOH, water:ethanol (70:30) solvent respectively using cyclic voltammetry technique. The morphology of the films constructed was determined by scanning electron microscope (SEM) while energy dispersive X-Ray analyzer (EDX) was used to establish the presence of organic PMAP and PPy film coating and its compositions. The corrosion performance of MS coated with both polymer films were investigated after 0.5 hours immersed in 0.5M NaCl aqueous solution by using polarization curves. It was found that PPy coating provides anodic protection while PMAP coating provides cathodic protection towards corrosion protection of mild steel substrate.

Synthesis of Nm-PHB (nanomelanin-polyhydroxy butyrate) nanocomposite film and its protective effect against biofilm-forming multi drug resistant Staphylococcus aureus.

PubMed

Kiran, George Seghal; Jackson, Stephen A; Priyadharsini, Sethu; Dobson, Alan D W; Selvin, Joseph

2017-08-22

Melanin is a dark brown ubiquitous photosynthetic pigment which have many varied and ever expanding applications in fabrication of radio-protective materials, food packaging, cosmetics and in medicine. In this study, melanin production in a Pseudomonas sp. which was isolated from the marine sponge Tetyrina citirna was optimized employing one-factor at a time experiments and characterized for chemical nature and stability. Following sonication nucleated nanomelanin (Nm) particles were formed and evaluated for antibacterial and antioxidant properties. Nanocomposite film was fabricated using combinations (% w/v) of polyhydroxy butyrate-nanomelanin (PHB:Nm) blended with 1% glycerol. The Nm was found to be spherical in shape with a diameter of 100-140 nm and showed strong antimicrobial activity against both Gram positive and Gram negative bacteria. The Nm-PHB nanocomposite film was homogeneous, smooth, without any cracks, and flexible. XRD and DSC data indicated that the film was crystalline in nature, and was thermostable up to 281.87 °C. This study represents the first report on the synthesis of Nm and fabrication of Nm-PHB nanocomposite film which show strong protective effect against multidrug resistant Staphyloccoccus aureus. Thus this Nm-PHB nanocomposite film may find utility as packaging material for food products by protecting the food products from oxidation and bacterial contamination.

Undercutting of defects in thin film protective coatings on polymer surfaces exposed to atomic oxygen

NASA Technical Reports Server (NTRS)

Rutledge, Sharon K.; Mihelcic, Judith A.

1989-01-01

Protection for polymeric surfaces is needed to make them durable in the low Earth orbital environment, where oxidation by atomic oxygen is the predominant failure mechanism. Thin film coatings of oxides such as silicon dioxide are viable candidates to provide this protection, but concern has been voiced over the ability of these coatings to protect when defects are present in the coating due to surface anomalies occurring during the deposition process, handling, or micrometeoroid and debris bombardment in low Earth orbit. When a defected coating protecting a polymer substrate is exposed to atomic oxygen, the defect provides a pathway to the underlying polymer allowing oxidation and subsequent undercutting to occur. Defect undercutting was studied for sputter deposited coatings of silicon dioxide on polyimide Kapton. Preliminary results indicate that undercutting may be limited as long as the coating remains intact with the substrate. Therefore, coatings may not need to be defect free to give protection to the underlying surface.

Performance and properties of atomic oxygen protective coatings for polymeric materials

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Lamoreaux, Cynthia

1992-01-01

Such large LEO spacecraft as the Space Station Freedom will encounter high atomic oxygen fluences which entail the use of protective coatings for their polymeric structural materials. Such coatings have demonstrated polymer mass losses due to oxidation that are much smaller than those of unprotected materials. Attention is here given to protective and/or electrically conductive coatings of SiO(x), Ge, and indium-tin oxide which have been exposed to atomic oxygen in order to ascertain mass loss, electrical conductivity, and optical property dependence on atomic oxygen exposure.

Do petroleum-based protective coatings add fuel value to slash

Treesearch

James L. Murphy; Charles W. Philpot

1965-01-01

Asphalts and wax emulsions have been recommended as protective coatings to help obtain clean, safe burns in slash disposal work. Fuel value determinations in the laboratory indicate that such coatings add little to the fuel value of slash.

Sintered tantalum carbide coatings on graphite substrates: Highly reliable protective coatings for bulk and epitaxial growth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, Daisuke; Suzumura, Akitoshi; Shigetoh, Keisuke

2015-02-23

Highly reliable low-cost protective coatings have been sought after for use in crucibles and susceptors for bulk and epitaxial film growth processes involving wide bandgap materials. Here, we propose a production technique for ultra-thick (50–200 μmt) tantalum carbide (TaC) protective coatings on graphite substrates, which consists of TaC slurry application and subsequent sintering processes, i.e., a wet ceramic process. Structural analysis of the sintered TaC layers indicated that they have a dense granular structure containing coarse grain with sizes of 10–50 μm. Furthermore, no cracks or pinholes penetrated through the layers, i.e., the TaC layers are highly reliable protective coatings. The analysismore » also indicated that no plastic deformation occurred during the production process, and the non-textured crystalline orientation of the TaC layers is the origin of their high reliability and durability. The TaC-coated graphite crucibles were tested in an aluminum nitride (AlN) sublimation growth process, which involves extremely corrosive conditions, and demonstrated their practical reliability and durability in the AlN growth process as a TaC-coated graphite. The application of the TaC-coated graphite materials to crucibles and susceptors for use in bulk AlN single crystal growth, bulk silicon carbide (SiC) single crystal growth, chemical vapor deposition of epitaxial SiC films, and metal-organic vapor phase epitaxy of group-III nitrides will lead to further improvements in crystal quality and reduced processing costs.« less

Graphene Nano-Composites for Hypervelocity Impact Applications

NASA Astrophysics Data System (ADS)

Manasrah, Alharith

The Low Earth Orbit (LEO) is a harsh environment cluttered with natural meteoroids and man-made debris, which can travel at velocities approaching 15 km/s. Most space activities within the LEO will encounter this environment. Thus, the spacecraft and its hardware must be designed to survive debris impact. This research introduces new procedures to produce a nano-composite material with mortar-brick nano-structure inspired from nacre. Nacre-like composites were successfully manufactured, based on three host polymers, with a wide range of graphene concentrations. The manufactured exfoliated graphene nano-platelet, embedded in a host polymer, provided good potential for enhancement of the hypervelocity impact (HVI) shield resistance. The nano-composites are suggested for use as a coating. Moreover, explicit dynamic finite element studies were conducted for further investigation of the hypervelocity impact of the graphene-based coatings in order to understand the effect of the coating on the crater formation and the exit velocity. This dissertation presents the results of the characterization and numerical sensitivity study of the developed material parameters. The numerical simulations were performed by implementing Autodyn smooth particle hydrodynamics. This study provides innovative, low-weight shielding enhancements for spacecraft, as well as other promising applications for the manufactured nano-composites.

Extraordinary Corrosion Protection from Polymer-Clay Nanobrick Wall Thin Films.

PubMed

Schindelholz, Eric J; Spoerke, Erik D; Nguyen, Hai-Duy; Grunlan, Jaime C; Qin, Shuang; Bufford, Daniel C

2018-06-20

Metals across all industries demand anticorrosion surface treatments and drive a continual need for high-performing and low-cost coatings. Here we demonstrate polymer-clay nanocomposite thin films as a new class of transparent conformal barrier coatings for protection in corrosive atmospheres. Films assembled via layer-by-layer deposition, as thin as 90 nm, are shown to reduce copper corrosion rates by >1000× in an aggressive H 2 S atmosphere. These multilayer nanobrick wall coatings hold promise as high-performing anticorrosion treatment alternatives to costlier, more toxic, and less scalable thin films, such as graphene, hexavalent chromium, or atomic-layer-deposited metal oxides.

Evaluation of Thermal Control Coatings for Flexible Ceramic Thermal Protection Systems

NASA Technical Reports Server (NTRS)

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

1997-01-01

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

Nuclear Technology. Course 30: Mechanical Inspection. Module 30-6, Protective Coating Inspection.

ERIC Educational Resources Information Center

Espy, John

This sixth in a series of eight modules for a course titled Mechanical Inspection describes the duties of the nuclear quality assurance/quality control technician that are associated with protective coatings, and the national standards that govern the selection, application, and inspection of protective coatings for the reactor containment…

Characterization of the corrosion protection mechanism of cerium-based conversion coatings on high strength aluminum alloys

NASA Astrophysics Data System (ADS)

Pinc, William Ross

The aim of the work presented in this dissertation is to investigate the corrosion protection mechanism of cerium-based conversion coatings (CeCCs) used in the corrosion protection of high strength aluminum alloys. The corrosion resistance of CeCCs involves two general mechanisms; barrier and active. The barrier protection mechanism was influenced by processing parameters, specifically surface preparation, post-treatment, and the use of gelatin. Post-treatment and the addition of gelatin to the coating solution resulted in fewer cracks and transformation of the coating to CePO4, which increased the corrosion resistance by improving the barrier aspect of CeCCs. CeCCs were found to best act as barriers when crack size was limited and CePO4 was present in the coating. CeCCs were found to protect areas of the substrate that were exposed in the coating, indicating that the coatings were more than simple barriers. CeCCs contained large cracks, underneath which subsurface crevices were connected to the surface by the cracks. Despite the observation that no cerium was present in crevices, coatings with crevices exhibited significant corrosion protection. The impedance of post-treated coatings with crevices increased during salt spray exposure. The increase in impedance was associated with the formation of protective oxides / hydroxides; however, crevice-free coatings also exhibited active protection leading to the conclusion that the formation of interfacial layers between the CeCC and the substrate also contributed to the active protection. Based on the overall results of the study, the optimal corrosion protection of CeCCs occurred when processing conditions produced coatings with morphologies and compositions that facilitated both the barrier and active protection mechanisms.

Colorless polyimide/organoclay nanocomposite substrates for flexible organic light-emitting devices.

PubMed

Kim, Jin-Hoe; Choi, Myeon-Chon; Kim, Hwajeong; Kim, Youngkyoo; Chang, Jin-Hae; Han, Mijeong; Kim, Il; Ha, Chang-Sik

2010-01-01

We report the preparation and application of indium tin oxide (ITO) coated fluorine-containing polyimide/organoclay nanocomposite substrate. Fluorine-containing polyimide/organoclay nanocomposite films were prepared through thermal imidization of poly(amic acid)/organoclay mixture films, whilst on which ITO thin films were coated on the films using a radio-frequency planar magnetron sputtering by varying the substrate temperature and the ITO thickness. Finally the ITO coated fluorine-containing polyimide/organoclay nanocomposite substrate was employed to make flexible organic light-emitting devices (OLED). Results showed that the lower sheet resistance was achieved when the substrate temperature was high and the ITO film was thick even though the optical transmittance was slightly lowered as the thickness increased. approximately 10 nm width ITO nanorods were found for all samples but the size of clusters with the nanorods was generally increased with the substrate temperature and the thickness. The flexible OLED made using the present substrate was quite stable even when the device was extremely bended.

Chemical vapor deposited silica coatings for solar mirror protection

NASA Technical Reports Server (NTRS)

Gulino, Daniel A.; Dever, Therese M.; Banholzer, William F.

1988-01-01

A variety of techniques is available to apply protective coatings to oxidation susceptible spacecraft components, and each has associated advantages and disadvantages. Film applications by means of chemical vapor deposition (CVD) has the advantage of being able to be applied conformally to objects of irregular shape. For this reason, a study was made of the oxygen plasma durability of thin film (less than 5000 A) silicon dioxide coatings applied by CVD. In these experiments, such coatings were applied to silver mirrors, which are strongly subject to oxidation, and which are proposed for use on the space station solar dynamic power system. Results indicate that such coatings can provide adequate protection without affecting the reflectance of the mirror. Scanning electron micrographs indicated that oxidation of the silver layer did occur at stress crack locations, but this did not affect the measured solar reflectances. Oxidation of the silver did not proceed beyond the immediate location of the crack. Such stress cracks did not occur in thinner silica flims, and hence such films would be desirable for this application.

Chemical vapor deposited silica coatings for solar mirror protection

NASA Technical Reports Server (NTRS)

Gulino, Daniel A.; Dever, Therese M.; Banholzer, William F.

1988-01-01

A variety of techniques is available to apply protective coatings to oxidation susceptible spacecraft components, and each has associated advantages and disadvantages. Film applications by means of chemical vapor deposition (CVD) has the advantage of being able to be applied conformally to objects of irregular shape. For this reason, a study was made of the oxygen plasma durability of thin film (less than 5000 A) silicon dioxide coatings applied by CVD. In these experiments, such coatings were applied to silver mirrors, which are strongly subject to oxidation, and which are proposed for use on the space station solar dynamic power system. Results indicate that such coatings can provide adequate protection without affecting the reflectance of the mirror. Scanning electron micrographs indicated that oxidation of the silver layer did occur at stress crack locations, but this did not affect the measured solar reflectances. Oxidation of the silver did not proceed beyond the immediate location of the crack. Such stress cracks did not occur in thinner silica films, and hence such films would be desirable for this application.

A platinized stainless steel fiber with in-situ coated polyaniline/polypyrrole/graphene oxide nanocomposite sorbent for headspace solid-phase microextraction of aliphatic aldehydes in rice samples.

PubMed

Ghiasvand, Alireza; Nasirian, Afagh; Koonani, Samira; Nouriasl, Kolsoum

2017-12-01

The surface of a stainless steel fiber was made larger, porous and cohesive by platinizing for tight attachment of its coating. Then it was coated by a polyaniline/polypyrrole/graphene oxide (PANI/PP/GO) nanocomposite film using electrochemical polymerization. The prepared PANI/PP/GO fiber was used for headspace solid-phase microextraction (HS-SPME) of linear aliphatic aldehydes in rice samples followed by GC-FID determination. To achieve the highest extraction efficiency, various experimental parameters including extraction time and temperature, matrix modifier and desorption condition were studied. The linear calibration curves were obtained over the range of 0.05-20 μg g -1 (R 2  > 0.99) for C 4 -C 11 aldehydes. The limits of detection were found to be in the range of 0.01-0.04 μg g -1 . RSD values were calculated to be <7.4 and 10.7% for intra- and inter-day, respectively. The superiority of the prepared nanocomposite SPME fiber was established by comparison of its results with those obtained by polydimethylsiloxane, carbowax-divinylbenzene, divinylbenzene-carboxen-polydimethylsiloxane and polyacrylate commercial ones. Finally, the nanocomposite fiber was used to extract and determine linear aliphatic aldehydes in 18 rice samples. Copyright © 2017 John Wiley & Sons, Ltd.

Protective Performance of Polyaniline-Sulfosalicylic Acid/Epoxy Coating for 5083 Aluminum

PubMed Central

Liu, Suyun; Liu, Li; Meng, Fandi; Li, Ying; Wang, Fuhui

2018-01-01

Epoxy coatings incorporating different content of sulfosalicylic acid doped polyaniline (PANI-SSA) have been investigated for corrosion protection of 5083 aluminum alloy in 3.5% NaCl solution. The performance of the coatings is studied using a combination of electrochemical impedance spectroscopy (EIS), open circuit potential (OCP), gravimetric tests, adhesion tests, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results demonstrate that the content of PANI-SSA not only affects the coating compactness and the transportation of aggressive medium, but also has a significant influence on the-based aluminum. The coating with 2 wt. % PANI-SSA exhibits the best corrosion inhibition due to its good protective properties and the formation of a complete PANI-SSA induced oxide layer. PMID:29438304

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.

[Studies on organic protective coatings for anti-atomic oxygen effects by spectrum analysis].

PubMed

Zhang, Lei

2004-11-01

This paper describes organic protective coatings on space material for anti-AO effects and the experiments to assess properties of the coatings. Organic protection was analyzed after exposures to ground state fast atomic (AO) radiation in the atomic oxygen beam facility for ground simulation experiments. The tests results have been analyzed with advanced FTIR, XPS and SEM. The test indicated that epoxy, alkyd and urethane organic coatings were highly reactive to AO with a strong degradation and changed in morphology of the surface layer. It is evident that siloxane coatings have excellent properties for anti-AO effects. The erosion product has SiO2 left on the surface, thus providing protection from further attack by the energetic oxygen atoms.

Corrosion protective coating for metallic materials

DOEpatents

Buchheit, Rudolph G.; Martinez, Michael A.

1998-01-01

Corrosion protective coatings for metallic materials, particularly aluminum and aluminum alloys, produced with simple, low-cost equipment and materials other than toxic metals or metal salts, or metal cyanides. The metallic material is cleaned, degreased, and deoxidized, the surface is converted to a substantially alkaline condition, and the surface is chemically sealed with inorganic metal compounds.

Development of Oxidation Protection Coatings for Gamma Titanium Aluminide Alloys

NASA Technical Reports Server (NTRS)

Wallace, T. A.; Bird, R. K.; Sankaran, S. N.

2003-01-01

Metallic material systems play a key role in meeting the stringent weight and durability requirements for reusable launch vehicle (RLV) airframe hot structures. Gamma titanium aluminides (gamma-TiAl) have been identified as high-payoff materials for high-temperature applications. The low density and good elevated temperature mechanical properties of gamma-TiAl alloys make them attractive candidates for durable lightweight hot structure and thermal protection systems at temperatures as high as 871 C. However, oxidation significantly degrades gamma-TiAl alloys under the high-temperature service conditions associated with the RLV operating environment. This paper discusses ongoing efforts at NASA Langley Research Center to develop durable ultrathin coatings for protecting gamma-TiAl alloys from high-temperature oxidation environments. In addition to offering oxidation protection, these multifunctional coatings are being engineered to provide thermal control features to help minimize heat input into the hot structures. This paper describes the coating development effort and discusses the effects of long-term high-temperature exposures on the microstructure of coated and uncoated gamma-TiAl alloys. The alloy of primary consideration was the Plansee alloy gamma-Met, but limited studies of the newer alloy gamma-Met-PX were also included. The oxidation behavior of the uncoated materials was evaluated over the temperature range of 704 C to 871 C. Sol-gel-based coatings were applied to the gamma-TiAl samples by dipping and spraying, and the performance evaluated at 871 C. Results showed that the coatings improve the oxidation resistance, but that further development is necessary.

Cirrus Dopant Nano-Composite Coatings

DTIC Science & Technology

2014-11-01

100 200 300 400 500 600 HARDNESS (HV) MICROHARDNESS - ELECTROPLATED NICKEL STANDARD DC PLATED DOPED DC PLATED DOPED PULSE PLATED ↑48% 10...STANDARD COATING HARDNESS (HV) DOPED COATING MICROHARDNESS - ELECTROPLATED ZN NI ↑32% DC ZnNi Cirrus ZnNi Current Test Applications cirrus nano

Protective coatings for high-temperature polymer matrix composites

NASA Technical Reports Server (NTRS)

Harding, David R.; Sutter, James K.; Papadopoulos, Demetrios S.

1993-01-01

Plasma-enhanced chemical vapor deposition was used to deposit silicon nitride on graphite-fiber-reinforced polyimide composites to protect against oxidation at elevated temperatures. The adhesion and integrity of the coating were evaluated by isothermal aging (371 C for 500 hr) and thermal cycling. The amorphous silicon nitride (a-SiN:H) coating could withstand stresses ranging from approximately 0.18 GPa (tensile) to -1.6 GPa (compressive) and provided a 30 to 80 percent reduction in oxidation-induced weight loss. The major factor influencing the effectiveness of a-SiN:H as a barrier coating against oxidation is the surface finish of the polymer composite.

Fabrication, characterization and gas sensing studies of PPy/MWCNT/SLS nanocomposite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tiwari, D. C., E-mail: dctiwari2001@yahoo.com; Atri, Priyanka, E-mail: dctiwari2001@yahoo.com; Sharma, R.

2014-04-24

Multiwall carbon nanotubes (MWCNT) coated with polypyrrole nanocomposite was prepared by in-situ chemical oxidative polymerization method in the presence of surfactant (SLS). The scanning electron microscope (SEM) pictures indicate the core shell structure of PPy/MWCNT/SLS nanocomposite. Nature of the prepared material was investigated by X-ray diffraction spectroscopy. This nanocomposite shows the excellent gas sensing behaviour for ammonia gas at 150 ppm and 300 ppm levels.

Titanium Nitride: An Oxidizable Coating for the High-Temperature Protection of Graphite

NASA Technical Reports Server (NTRS)

Wakelyn, N. T.

1961-01-01

A titanium nitride coating for graphite, prepared by deposition process, protected test specimens for 60 seconds the vapors in a supersonic ceramic-heated air jet with a stagnation temperature of approximately 2,250 K. For the same test conditions, coated specimens showed no damage to the graphite body for the 60-second test, whereas uncoated specimens were very severely damaged after 20 seconds and were destroyed toward the end of the test. A discussion of the coating of these graphite specimens and of some of the conditions necessary for the utilization of oxidizable substances as oxidation-protective coatings for bodies facing high convective heat transfer in the atmosphere is presented.

Protection of bronze artefacts through polymeric coatings based on nanocarriers filled with corrosion inhibitors

NASA Astrophysics Data System (ADS)

de Luna, Martina Salzano; Buonocore, Giovanna; Di Carlo, Gabriella; Giuliani, Chiara; Ingo, Gabriel M.; Lavorgna, Marino

2016-05-01

Protective coatings based on polymers synthesized from renewable sources (chitosan or an amorphous vinyl alcohol based polymer) have been prepared for the protection of bronze artifacts from corrosion. Besides acting as an effective barrier against corrosive species present in the environment, the efficiency of the coatings has been improved by adding corrosion inhibitor compounds (benzotriazole or mercaptobenzothiazole) to the formulations. The liquid medium of the formulations has been carefully selected looking at maximizing the wettability on the bronze substrate and optimizing the solvent evaporation rate. The minimum amount of inhibitor compounds has been optimized by performing accelerated corrosion tests on coated bronze substrates. The inhibitors have been directly dissolved in the coating-forming solutions and/or introduced by means of nanocarriers, which allow to control the release kinetics. The free dissolved inhibitor molecules immediately provide a sufficient protection against corrosion. On the other hand, the inhibitor molecules contained in the nanocarriers serve as long-term reservoir, which can be activated by external corrosion-related stimuli in case of particularly severe conditions. Particular attention has been paid to other features which affect the coating performances. Specifically, the adhesion of the protective polymer layer to the bronze substrate has been assessed, as well as its permeability properties and transparency, the latter being a fundamental feature of protective coating for cultural heritages. Finally, the protective efficiency of the produced smart coatings has been assessed through accelerated corrosion tests.

Fabrication of superhydrophobic surfaces based on ZnO-PDMS nanocomposite coatings and study of its wetting behaviour

NASA Astrophysics Data System (ADS)

Chakradhar, R. P. S.; Kumar, V. Dinesh; Rao, J. L.; Basu, Bharathibai J.

2011-08-01

Superhydrophobic surfaces based on ZnO-PDMS nanocomposite coatings are demonstrated by a simple, facile, time-saving, wet chemical route. ZnO nanopowders with average particle size of 14 nm were synthesized by a low temperature solution combustion method. Powder X-ray diffraction results confirm that the nanopowders exhibit hexagonal wurtzite structure and belong to space group P63 mc. Field emission scanning electron micrographs reveal that the nanoparticles are connected to each other to make large network systems consisting of hierarchical structure. The as formed ZnO coating exhibits wetting behaviour with Water Contact Angle (WCA) of ˜108°, however on modification with polydimethylsiloxane (PDMS), it transforms to superhydrophobic surface with measured contact and sliding angles for water at 155° and less than 5° respectively. The surface properties such as surface free energy ( γp), interfacial free energy ( γpw), and the adhesive work ( Wpw) were evaluated. Electron paramagnetic resonance (EPR) studies on superhydrophobic coatings revealed that the surface defects play a major role on the wetting behaviour. Advantages of the present method include the cheap and fluorine-free raw materials, environmentally benign solvents, and feasibility for applying on large area of different substrates.

Photocatalytic Nanocomposites for the Protection of European Architectural Heritage.

PubMed

Gherardi, Francesca; Roveri, Marco; Goidanich, Sara; Toniolo, Lucia

2018-01-03

In the field of stone protection, the introduction of inorganic nanoparticles, such as TiO₂, ZnO, and Ag in polymeric blends can enhance the protective action of pristine treatments, as well as confer additional properties (photocatalytic, antifouling, and antibacterial). In the framework of the "Nano-Cathedral" European project, nanostructured photocatalytic protective treatments were formulated by using different TiO₂ nanoparticles, solvents, and silane/siloxane systems in the blends. The results about the characterization and application of two promising nano-TiO₂ based products applied on Apuan marble and Ajarte limestone are here reported, aiming at investigating the complex system "treatment/stone-substrate". The nanocomposites show better performances when compared to a commercial reference siloxane based protective treatment, resulting in different performances once applied on different carbonatic substrates, with very low and high open porosity, confirming the necessity of correlating precisely the characteristics of the stone material to those of the protective formulations. In particular, the TiO₂ photocatalytic behavior is strictly linked to the amount of available nanoparticles and to the active surface area. The alkyl silane oligomers of the water-based formulation have a good penetration into the microstructure of Ajarte limestone, whereas the solvent-based and small size monomeric formulation shows better results for Apuan marble, granting a good coverage of the pores. The encouraging results obtained so far in lab will be confirmed by monitoring tests aiming at assessing the effectiveness of the treatments applied in pilot sites of historical Gothic Cathedrals.

Surface protection of austenitic steels by carbon nanotube coatings

NASA Astrophysics Data System (ADS)

MacLucas, T.; Schütz, S.; Suarez, S.; Mücklich, F.

2018-03-01

In the present study, surface protection properties of multiwall carbon nanotubes (CNTs) deposited on polished austenitic stainless steel are evaluated. Electrophoretic deposition is used as a coating technique. Contact angle measurements reveal hydrophilic as well as hydrophobic wetting characteristics of the carbon nanotube coating depending on the additive used for the deposition. Tribological properties of carbon nanotube coatings on steel substrate are determined with a ball-on-disc tribometer. Effective lubrication can be achieved by adding magnesium nitrate as an additive due to the formation of a holding layer detaining CNTs in the contact area. Furthermore, wear track analysis reveals minimal wear on the coated substrate as well as carbon residues providing lubrication. Energy dispersive x-ray spectroscopy is used to qualitatively analyse the elemental composition of the coating and the underlying substrate. The results explain the observed wetting characteristics of each coating. Finally, merely minimal oxidation is detected on the CNT-coated substrate as opposed to the uncoated sample.

Self-healing effect of the protective inhibitor-containing coatings on Mg alloys

NASA Astrophysics Data System (ADS)

Gnedenkov, A. S.; Sinebryukhov, S. L.; Mashtalyar, D. V.; Gnedenkov, S. V.

2017-09-01

The method of self-healing coating formation on the surface of magnesium alloys on the base of plasma electrolytic oxidation (PEO) with subsequent impregnation of the obtained layer with inhibitor has been suggested. The protective and electrochemical properties of such coatings have been described. Localised Scanning Electrochemical Methods were used for determining the kinetics and mechanism of the self-healing process. The treatment with the solution containing inhibitor enables us to increase the protective properties of the PEO-coating in 30 times in the corrosion-active environment.

High performance polypyrrole coating for corrosion protection and biocidal applications

NASA Astrophysics Data System (ADS)

Nautiyal, Amit; Qiao, Mingyu; Cook, Jonathan Edwin; Zhang, Xinyu; Huang, Tung-Shi

2018-01-01

Polypyrrole (PPy) coating was electrochemically synthesized on carbon steel using sulfonic acids as dopants: p-toluene sulfonic acid (p-TSA), sulfuric acid (SA), (±) camphor sulfonic acid (CSA), sodium dodecyl sulfate (SDS), and sodium dodecylbenzene sulfonate (SDBS). The effect of acidic dopants (p-TSA, SA, CSA) on passivation of carbon steel was investigated by linear potentiodynamic and compared with morphology and corrosion protection performance of the coating produced. The types of the dopants used were significantly affecting the protection efficiency of the coating against chloride ion attack on the metal surface. The corrosion performance depends on size and alignment of dopant in the polymer backbone. Both p-TSA and SDBS have extra benzene ring that stack together to form a lamellar sheet like barrier to chloride ions thus making them appropriate dopants for PPy coating in suppressing the corrosion at significant level. Further, adhesion performance was enhanced by adding long chain carboxylic acid (decanoic acid) directly in the monomer solution. In addition, PPy coating doped with SDBS displayed excellent biocidal abilities against Staphylococcus aureus. The polypyrrole coatings on carbon steels with dual function of anti-corrosion and excellent biocidal properties shows great potential application in the industry for anti-corrosion/antimicrobial purposes.

Corrosion protective coating for metallic materials

DOEpatents

Buchheit, R.G.; Martinez, M.A.

1998-05-26

Corrosion protective coatings for metallic materials, particularly aluminum and aluminum alloys, produced with simple, low-cost equipment and materials other than toxic metals or metal salts, or metal cyanides is disclosed. The metallic material is cleaned, degreased, and deoxidized, the surface is converted to a substantially alkaline condition, and the surface is chemically sealed with inorganic metal compounds. 1 fig.

Method of Fabricating Protective Coating for a Crucible with the Coating Having Channels Formed Therein

NASA Technical Reports Server (NTRS)

Grugel, Richard N. (Inventor)

2004-01-01

A method is provided for the fabrication of a protective coating for a crucible with channels being formed in the coating. A material is adhered to the outer wall of the crucible to form a pattern thereon. The outer wall of the crucible along with the pattern of material adhered thereto is next coated with another material. The material used to form the pattern should extend through the outer material coating to define at least one port therein. Next, the crucible with its pattern of material and outer coating material is heated to a temperature of transformation at which the pattern of material is transformed to a fluidic state while the crucible and outer coating material maintain their solid integrity. Such transformation could also be accomplished by using a solvent that causes the pattern of material to dissolve. Finally, the material in its fluidic state is removed via the at least one port formed in the outer material coating thereby leaving channels defined in the coating adjacent the outer wall of the crucible.

Self-assembly of nanocomposite materials

DOEpatents

Brinker, C. Jeffrey; Sellinger, Alan; Lu, Yunfeng

2001-01-01

A method of making a nanocomposite self-assembly is provided where at least one hydrophilic compound, at least one hydrophobic compound, and at least one amphiphilic surfactant are mixed in an aqueous solvent with the solvent subsequently evaporated to form a self-assembled liquid crystalline mesophase material. Upon polymerization of the hydrophilic and hydrophobic compounds, a robust nanocomposite self-assembled material is formed. Importantly, in the reaction mixture, the amphiphilic surfactant has an initial concentration below the critical micelle concentration to allow formation of the liquid-phase micellar mesophase material. A variety of nanocomposite structures can be formed, depending upon the solvent evaporazation process, including layered mesophases, tubular mesophases, and a hierarchical composite coating composed of an isotropic worm-like micellar overlayer bonded to an oriented, nanolaminated underlayer.

Failure Mechanisms of the Protective Coatings for the Hot Stamping Applications

NASA Astrophysics Data System (ADS)

Zhao, Chen

In the present study, four different nitriding techniques were carried on the ductile irons NAAMS-D6510 and cast steels NAAMS-S0050A, which are widely used stamping die materials; duplex treatments (PVD CrN coating+nitriding) were carried on H13 steels, which are common inserts for the hot stamping dies. Inclined impact-sliding wear tests were performed on the nitriding cases under simulated stamping conditions. Surface profilometer, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used to investigate the wear and failure mechanisms of the protective coatings. It was found that the nitrided ductile iron samples performed better than the nitrided cast steel specimens. High temperature inclined impact-sliding wear tests were carried out on the CrN coatings. It was found that the coating performed better at elevated temperature. XPS analysis indicated the top surface layer (about 3-4nm) of the coating was oxidized at 400 °C and formed a Cr2O3 protective film. The in-situ formation of the thin Cr2O3 protective layer likely led to the change of wear mechanisms from severe adhesive failure to mild abrasive wear.

Chitosan-58S bioactive glass nanocomposite coatings on TiO2 nanotube: Structural and biological properties

NASA Astrophysics Data System (ADS)

Mokhtari, H.; Ghasemi, Z.; Kharaziha, M.; Karimzadeh, F.; Alihosseini, F.

2018-05-01

Bacterial infection and insignificant osseointegration have been recognized as the main reasons of the failures of titanium based implants. The aim of this study was to apply titanium oxide nanotube (TNT) array on titanium using electrochemical anodization process as a more appropriate substrate for chitosan and chitosan-58S bioactive glass (BG) (58S-BG-Chitosan) nanocomposite coatings covered TNTs (TNT/Chiosan, TNT/58S-BG-Chitosan, respectively) through a conventional dip-coating process. Results showed that a TNT layer with average inner diameter of 82 ± 19 nm and wall's thickness of 23 ± 9 nm was developed on titanium surface using electrochemical anodization process. Roughness and contact angle measurement showed that TNT with Ra = 449 nm had highest roughness and hydrophilicity which then reduced to 86 nm and 143 nm for TNT/Chitosan and TNT/58S-BG-Chitosan, respectively. In vitro bioactivity evaluation in simulated buffer fluid (SBF) solution and antibacterial activity assay predicted that TNT/58S-BG-Chitosan was superior in bone like apatite formation and antibacterial activity against both gram-positive and gram-negative bacteria compared to Ti, TNT and TNT/Chitosan samples, respectively. Results revealed the noticeable MG63 cell attachment and proliferation on TNT/58S-BG-Chitosan coating compared to those of uncoated TNTs. These results confirmed the positive effect of using TNT substrate for natural polymer coating on improved bioactivity of implant.

Understanding the Antifungal Mechanism of Ag@ZnO Core-shell Nanocomposites against Candida krusei.

PubMed

Das, Bhaskar; Khan, Md Imran; Jayabalan, R; Behera, Susanta K; Yun, Soon-Il; Tripathy, Suraj K; Mishra, Amrita

2016-11-04

In the present paper, facile synthesis of Ag@ZnO core-shell nanocomposites is reported where zinc oxide is coated on biogenic silver nanoparticles synthesized using Andrographis paniculata and Aloe vera leaf extract. Structural features of as synthesized nanocomposites are characterized by UV-visible spectroscopy, XRD, and FTIR. Morphology of the above core-shell nanocomposites is investigated by electron microscopy. As synthesized nanocomposite material has shown antimicrobial activity against Candida krusei, which is an opportunistic pathogen known to cause candidemia. The possible mode of activity of the above material has been studied by in-vitro molecular techniques. Our investigations have shown that surface coating of biogenic silver nanoparticles by zinc oxide has increased its antimicrobial efficiency against Candida krusei, while decreasing its toxicity towards A431 human epidermoid carcinoma cell lines.

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

NASA Technical Reports Server (NTRS)

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

2009-01-01

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

Poly(vinyl acetate)/clay nanocomposite materials for organic thin film transistor application.

PubMed

Park, B J; Sung, J H; Park, J H; Choi, J S; Choi, H J

2008-05-01

Nanocomposite materials of poly(vinyl acetate) (PVAc) and organoclay were fabricated, in order to be utilized as dielectric materials of the organic thin film transistor (OTFT). Spin coating condition of the nanocomposite solution was examined considering shear viscosity of the composite materials dissolved in chloroform. Intercalated structure of the PVAc/clay nanocomposites was characterized using both wide-angle X-ray diffraction and TEM. Fracture morphology of the composite film on silicon wafer was also observed by SEM. Dielectric constant (4.15) of the nanocomposite materials shows that the PVAc/clay nanocomposites are applicable for the gate dielectric materials.

How the Toughest Inorganic Fullerene Cages Absorb Shockwave Pressures in a Protective Nanocomposite: Experimental Evidence from Two In Situ Investigations.

PubMed

Xu, Fang; Kobayashi, Takamichi; Yang, Zhuxian; Sekine, Toshimori; Chang, Hong; Wang, Nannan; Xia, Yongde; Zhu, Yanqiu

2017-08-22

Nanocomposites fabricated using the toughest caged inorganic fullerene WS 2 (IF-WS 2 ) nanoparticles could offer ultimate protection via absorbing shockwaves; however, if the IF-WS 2 nanomaterials really work, how they behave and what they experience within the nanocomposites at the right moment of impact have never been investigated effectively, due to the limitations of existing investigation techniques that are unable to elucidate the true characteristics of high-speed impacts in composites. We first fabricated Al matrix model nanocomposites and then unlocked the exact roles of IF-WS 2 in it at the exact moment of impact, at a time resolution that has never been attempted before, using two in situ techniques. We find that the presence of IF-WS 2 reduced the impact velocity by over 100 m/s and in pressure by at least 2 GPa against those Al and hexagonal WS 2 platelet composites at an impact speed of 1000 m/s. The IF-WS 2 composites achieved an intriguing inelastic impact and outperformed other reference composites, all originating from the "balloon effect" by absorbing the shockwave pressures. This study not only provides fundamental understanding for the dynamic performance of composites but also benefits the development of protective nanocomposite engineering.

Efficient drug delivery using SiO2-layered double hydroxide nanocomposites.

PubMed

Li, Li; Gu, Zi; Gu, Wenyi; Liu, Jian; Xu, Zhi Ping

2016-05-15

MgAl-layered double hydroxide (MgAl-LDH) nanoparticles have great potentials in drug and siRNA delivery. In this work, we used a nanodot-coating strategy to prepare SiO2 dot-coated layered double hydroxide (SiO2@MgAl-LDH) nanocomposites with good dispersibility and controllable size for drug delivery. The optimal SiO2@MgAl-LDH nanocomposite was obtained by adjusting synthetic parameters including the mass ratio of MgAl-LDH to SiO2, the mixing temperature and time. The optimal SiO2@MgAl-LDH nanocomposite was shown to have SiO2 nanodots (10-15nm in diameter) evenly deposited on the surface of MgAl-LDHs (110nm in diameter) with the plate-like morphology and the average hydrodynamic diameter of 170nm. We further employed SiO2@MgAl-LDH nanocomposite as a nanocarrier to deliver methotrexate (MTX), a chemotherapy drug, to the human osteosarcoma cell (U2OS) and found that MTX delivered by SiO2@MgAl-LDH nanocomposite apparently inhibited the U2OS cell growth. Copyright © 2016 Elsevier Inc. All rights reserved.

IN SITU Deposition of Fe-TiC Nanocomposite on Steel by Laser Cladding

NASA Astrophysics Data System (ADS)

Razavi, Mansour; Rahimipour, Mohammad Reza; Ganji, Mojdeh; Ganjali, Mansoreh; Gangali, Monireh

The possibility of deposition of Fe-TiC nanocomposite on the surface of carbon steel substrate with the laser coating method had been investigated. Mechanical milling was used for the preparation of raw materials. The mixture of milled powders was used as a coating material on the substrate steel surface and a CO2 laser was used in continuous mode for coating. Microstructural studies were performed by scanning electron microscopy. Determinations of produced phases, crystallite size and mean strain have been done by X-ray diffraction. The hardness and wear resistance of coated samples were measured. The results showed that the in situ formation of Fe-TiC nanocomposite coating using laser method is possible. This coating has been successfully used to improve the hardness and wear resistance of the substrate so that the hardness increased by about six times. Coated iron and titanium carbide crystallite sizes were in the nanometer scale.

Electrochemical investigation of powder coatings and their application to magnesium-rich primers for corrosion protection

NASA Astrophysics Data System (ADS)

Orgon, Casey Roy

Corrosion is the decomposition of metal and metal alloys which threatens the integrity of man-made structures. One of the more efficient methods of delaying the corrosion process in metals is by coatings. In this work, the durability of two polyester powder coatings were investigated for corrosion protection of AA-2024-T3. Polyester powder coatings crosslinked by either triglycidyl isocyanurate (TGIC) or beta-hydroxyalkyl amide (HAA) compounds were prepared and investigated for barrier protection of metal substrates by electrochemical impedance spectroscopy (EIS). Polyester-TGIC coatings were found to provide better long-term protection, which can be attributed to the increased mechanical strength and higher concentration of crosslinking in the coating films. Additionally, the polyester powder coatings, along with a fusion bonded epoxy (FBE) were investigated for their compatibility as a topcoat for magnesium-rich primers (MgRP). Under proper application conditions, powder topcoats were successfully applied to cured MgRP while corrosion protection mechanisms of each system were maintained.

Influence of dielectric protective layer on laser damage resistance of gold coated gratings

NASA Astrophysics Data System (ADS)

Wu, Kepeng; Ma, Ping; Pu, Yunti; Xia, Zhilin

2016-03-01

Aiming at the problem that the damage threshold of gold coated grating is relatively low, a dielectric film is considered on the gold coated gratings as a protective layer. The thickness range of the protective layer is determined under the prerequisite that the diffraction efficiency of the gold coated grating is reduced to an acceptable degree. In this paper, the electromagnetic field, the temperature field and the stress field distribution in the grating are calculated when the silica and hafnium oxide are used as protective layers, under the preconditions of the electromagnetic field distribution of the gratings known. The results show that the addition of the protective layer changes the distribution of the electromagnetic field, temperature field and stress field in the grating, and the protective layer with an appropriate thickness can improve the laser damage resistance of the grating.

Wear mechanisms of the biotribological nanocomposite a-C : H coatings implanted by metallic nanoparticles.

PubMed

Major, L; Janusz, M; Lackner, J M; Kot, M; Dyner, M; Major, B

2017-10-01

Recently, to reduce the residual stress and increase the mechanical properties of a-C:H coatings, metallic nanoparticles have been implanted into their structure. In the present work, to improve the properties of the coating, metallic nanoparticles, including Cu, Nb, Ta, Zr, AgPt and Ag, were inserted into the a-C:H structure. The applied biological and mechanical analysis allowed the optimal biotribological parameters to be indicated for the potential application as protective coatings for metallic medical tools. Wear mechanisms operating at the small length of the designed biotribological coating, such as a-C:H implanted by Zr nanoparticles, were studied by means of transmission electron microscopy (TEM). The TEM analysis confirmed very good coating adhesion to the metallic substrate. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Corrosion Embrittlement of Duralumin IV : The Use of Protective Coatings

NASA Technical Reports Server (NTRS)

Rawdon, Henry S

1928-01-01

Although the corrosion resistance of sheet duralumin can be greatly improved by suitable heat treatment, protection of the surface is still necessary if long life under varied service conditions is to be insured. The coatings used for this purpose may be grouped into three classes: the varnish type of coating, the oxide type produced by a chemical treatment of the surface, and metallic coatings, of which aluminum appears to be the most promising. Since the necessary weather exposure tests are not complete, some of the conclusions regarding the value of various surface coatings are necessarily tentative.

Coated columbium thermal protection systems: An assessment of technological readiness

NASA Technical Reports Server (NTRS)

Levine, S. R.; Grisaffe, S. J.

1973-01-01

Evaluation and development to date show that of the coated columbium alloys FS-85 coated with R512E shows significant promise for a reusable thermal protection system (TPS) as judged by environmental resistance and the retention of mechanical properties and structural integrity of panels upon repeated reentry simulation. Production of the alloy, the coating, and full-sized TPS panels is well within current manufacturing technology. Small defects which arise from impact damage or from local coating breakdown do not appear to have serious immediate consequences in the use environment anticipated for the space shuttle orbiter TPS.

Electrically Conductive and Protective Coating for Planar SOFC Stacks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Jung-Pyung; Stevenson, Jeffry W.

Ferritic stainless steels are preferred interconnect materials for intermediate temperature SOFCs because of their resistance to oxidation, high formability and low cost. However, their protective oxide layer produces Cr-containing volatile species at SOFC operating temperatures and conditions, which can cause cathode poisoning. Electrically conducting spinel coatings have been developed to prevent cathode poisoning and to maintain an electrically conductive pathway through SOFC stacks. However, this coating is not compatible with the formation of stable, hermetic seals between the interconnect frame component and the ceramic cell. Thus, a new aluminizing process has been developed by PNNL to enable durable sealing, preventmore » Cr evaporation, and maintain electrical insulation between stack repeat units. Hence, two different types of coating need to have stable operation of SOFC stacks. This paper will focus on the electrically conductive coating process. Moreover, an advanced coating process, compatible with a non-electrically conductive coating will be« less

Surface modification of a polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) nanocomposite polymer as a stent coating for enhanced capture of endothelial progenitor cells

PubMed Central

Tan, Aaron; Farhatnia, Yasmin; Goh, Debbie; G, Natasha; de Mel, Achala; Lim, Jing; Teoh, Swee-Hin; Malkovskiy, Andrey V; Chawla, Reema; Rajadas, Jayakumar; Cousins, Brian G; Hamblin, Michael R; Alavijeh, Mohammad S; Seifalian, Alexander M

2013-01-01

An unmet need exists for the development of next-generation multifunctional nanocomposite materials for biomedical applications, particularly in the field of cardiovascular regenerative biology. Herein, we describe the preparation and characterization of a novel polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) nanocomposite polymer with covalently attached anti-CD34 antibodies to enhance capture of circulating endothelial progenitor cells (EPC). This material may be used as a new coating for bare metal stents used after balloon angioplasty to improve re-endothelialization. Biophysical characterization techniques were used to assess POSS-PCU and its subsequent functionalization with anti-CD34 antibodies. Results indicated successful covalent attachment of anti-CD34 antibodies on the surface of POSS-PCU leading to an increased propensity for EPC capture, whilst maintaining in vitro biocompatibility and hemocompatibility. POSS-PCU has already been used in 3 first-in-man studies, as a bypass graft, lacrimal duct and a bioartificial trachea. We therefore postulate that its superior biocompatibility and unique biophysical properties would render it an ideal candidate for coating medical devices, with stents as a prime example. Taken together, anti-CD34 functionalized POSS-PCU could form the basis of a nano-inspired polymer platform for the next generation stent coatings. PMID:24706135

Thin coatings for protecting titanium aluminides in high-temperature oxidizing environments

NASA Technical Reports Server (NTRS)

Wiedemann, K. E.; Taylor, P. J.; Clark, R. K.; Wallace, T. A.

1991-01-01

Titanium aluminides have high specific strengths at high temperatures but are susceptible to environmental attack. Their use in many aerospace applications would require that they be protected with coatings that, for structural efficiency, must be thin. It is conceivable that acceptable coatings might be found in several oxide systems, and consequently, oxide coatings of many compositions were prepared from sol-gels for study. Response-surface methodology was used to refine coating compositions and factorial experiments were used to develop coating strategies. Oxygen permeability diagrams of two-layer coatings for several oxide systems, an analysis of multiple-layer coatings on rough and polished surfaces, and modeling of the oxidation weight gain are presented.

Electrodeposition of r-GO/SiC nano-composites on Magnesium and its Corrosion Behavior in Aqueous Electrolyte

NASA Astrophysics Data System (ADS)

Kavimani, V.; K, Soorya Prakash; R, Rajesh; Rammasamy, Devaraj; Selvaraj, Nivas Babu; Yang, Tao; Prabakaran, Balasubramanian; Jothi, Sathiskumar

2017-12-01

In this paper a detailed investigation for corrosion behavior of magnesium substrate electrodeposited differently by nanoparticles like Reduced Graphene Oxide (r-GO synthesized through Modified Hummer's Method), Silicon Carbide (SiCsbnd mechanically alloyed) and also r-GO/SiC nanocomposites (dispersed through ultrasonication process) as coating materials for varying time period was done. Synthesized nanocomposite was characterized through various physio-chemical techniques and confirmation of the same was carried out. Surface morphology of the developed set of specimens was scrutinized through SEM and EDAX which establishes a clean surface coating with minimal defects attainment through electro deposition technique. Electrochemical corrosion behavior for the magnesium substrates coated with r-GO, SiC, r-GO/SiC for 5 and 10 min coating time period was conceded over in 0.1 M of NaCl and Na2SO4 aqueous solution using Tafel polarization and then compared with a pure magnesium substrate. r-GO/SiC nanocomposite coated magnesium substrate showcased a drastic breakthrough in corrosion resistance when compared with other set of specimens in aqueous medium. Delamination behavior for the same set of specimens was carried and the r-GO/SiC nanocomposite coated magnesium exposed a minimum delamination area accounting to the hydrophobic property of graphene and the binding effect of SiC nano particles.

SiC Protective Coating for Photovoltaic Retinal Prostheses

PubMed Central

Lei, Xin; Kane, Sheryl; Cogan, Stuart; Lorach, Henri; Galambos, Ludwig; Huie, Philip; Mathieson, Keith; Kamins, Theodore; Harris, James; Palanker, Daniel

2016-01-01

Objective To evaluate PECVD SiC as a protective coating for retinal prostheses and other implantable devices, and to study their failure mechanisms in vivo. Approach Retinal prostheses were implanted in rats subretinally for up to 1 year. Degradation of implants was characterized by optical and scanning electron microscopy. Dissolution rates of SiC, SiNx and thermal SiO2 were measured in accelerated soaking tests in saline at 87°C. Defects in SiC films were revealed and analyzed by selectively removing the materials underneath those defects. Main results At 87°C SiNx dissolved at 18.3±0.3nm/day, while SiO2 grown at high temperature (1000°C) dissolved at 1.04±0.08A/day. SiC films demonstrated the best stability, with no quantifiable change after 112 days. Defects in thin SiC films appeared primarily over complicated topography and rough surfaces. Significance SiC coatings demonstrating no erosion in accelerated aging test for 112 days at 87°C, equivalent to about 10 years in vivo, can offer effective protection of the implants. Photovoltaic retinal prostheses with PECVD SiC coatings exhibited effective protection from erosion during the 4-month follow-up in vivo. The optimal thickness of SiC layers is about 560nm, as defined by anti-reflective properties and by sufficient coverage to eliminate defects. PMID:27323882

Review of Rover fuel element protective coating development at Los Alamos

NASA Technical Reports Server (NTRS)

Wallace, Terry C.

1991-01-01

The Los Alamos Scientific Laboratory (LASL) entered the nuclear propulsion field in 1955 and began work on all aspects of a nuclear propulsion program with a target exhaust temperature of about 2750 K. A very extensive chemical vapor deposition coating technology for preventing catastrophic corrosion of reactor core components by the high temperature, high pressure hydrogen propellant gas was developed. Over the 17-year term of the program, more than 50,000 fuel elements were coated and evaluated. Advances in performance were achieved only through closely coupled interaction between the developing fuel element fabrication and protective coating technologies. The endurance of fuel elements in high temperature, high pressure hydrogen environment increased from several minutes at 2000 K exit gas temperature to 2 hours at 2440 K exit gas temperature in a reactor test and 10 hours at 2350 K exit gas temperature in a hot gas test. The purpose of this paper is to highlight the rationale for selection of coating materials used (NbC and ZrC), identify critical fuel element-coat interactions that had to be modified to increase system performance, and review the evolution of protective coating technology.

Surface plasmon resonance-based fiber-optic hydrogen gas sensor utilizing palladium supported zinc oxide multilayers and their nanocomposite.

PubMed

Tabassum, Rana; Gupta, Banshi D

2015-02-10

We analyze surface plasmon resonance-based fiber-optic sensor for sensing of small concentrations of hydrogen gas in the visible region of the electromagnetic spectrum. One of the two probes considered has multilayers of zinc oxide (ZnO) and palladium (Pd) while the other has layer of their composite over a silver coated unclad core of the fiber. The analysis is carried out for different volume fractions of palladium nanoparticles dispersed in zinc oxide host material in the nanocomposite layer. For the analysis, a Maxwell-Garnett model is adopted for calculating the dielectric function of a ZnO:Pd nanocomposite having nanoparticles of dimensions smaller than the wavelength of radiation used. The effects of the volume fraction of the nanoparticles in the nanocomposite and the thickness of the nanocomposite layer on the figure of merit of the sensor have been studied. The film thickness of the layer and the volume fraction of nanoparticles in the ZnO:Pd nanocomposite layer have been optimized to achieve the maximum value of the figure of merit of the sensor. It has been found that the figure of merit of the sensing probe coated with ZnO:Pd nanocomposite is more than twofold of the sensing probe coated with multilayers of Pd and ZnO over a silver coated unclad core of the fiber; hence, the sensor with a nanocomposite layer works better than that with multilayers of zinc oxide and palladium. The sensor can be used for online monitoring and remote sensing of hydrogen gas.

Polymer and ceramic nanocomposites for aerospace applications

NASA Astrophysics Data System (ADS)

Rathod, Vivek T.; Kumar, Jayanth S.; Jain, Anjana

2017-11-01

This paper reviews the potential of polymer and ceramic matrix composites for aerospace/space vehicle applications. Special, unique and multifunctional properties arising due to the dispersion of nanoparticles in ceramic and metal matrix are briefly discussed followed by a classification of resulting aerospace applications. The paper presents polymer matrix composites comprising majority of aerospace applications in structures, coating, tribology, structural health monitoring, electromagnetic shielding and shape memory applications. The capabilities of the ceramic matrix nanocomposites to providing the electromagnetic shielding for aircrafts and better tribological properties to suit space environments are discussed. Structural health monitoring capability of ceramic matrix nanocomposite is also discussed. The properties of resulting nanocomposite material with its disadvantages like cost and processing difficulties are discussed. The paper concludes after the discussion of the possible future perspectives and challenges in implementation and further development of polymer and ceramic nanocomposite materials.

Photocatalytic Nanocomposites for the Protection of European Architectural Heritage

PubMed Central

Roveri, Marco; Goidanich, Sara; Toniolo, Lucia

2018-01-01

In the field of stone protection, the introduction of inorganic nanoparticles, such as TiO2, ZnO, and Ag in polymeric blends can enhance the protective action of pristine treatments, as well as confer additional properties (photocatalytic, antifouling, and antibacterial). In the framework of the “Nano-Cathedral” European project, nanostructured photocatalytic protective treatments were formulated by using different TiO2 nanoparticles, solvents, and silane/siloxane systems in the blends. The results about the characterization and application of two promising nano-TiO2 based products applied on Apuan marble and Ajarte limestone are here reported, aiming at investigating the complex system “treatment/stone-substrate”. The nanocomposites show better performances when compared to a commercial reference siloxane based protective treatment, resulting in different performances once applied on different carbonatic substrates, with very low and high open porosity, confirming the necessity of correlating precisely the characteristics of the stone material to those of the protective formulations. In particular, the TiO2 photocatalytic behavior is strictly linked to the amount of available nanoparticles and to the active surface area. The alkyl silane oligomers of the water-based formulation have a good penetration into the microstructure of Ajarte limestone, whereas the solvent-based and small size monomeric formulation shows better results for Apuan marble, granting a good coverage of the pores. The encouraging results obtained so far in lab will be confirmed by monitoring tests aiming at assessing the effectiveness of the treatments applied in pilot sites of historical Gothic Cathedrals. PMID:29301338

Sustainable design and manufacturing of multifunctional polymer nanocomposite coatings: A multiscale systems approach

NASA Astrophysics Data System (ADS)

Xiao, Jie

Polymer nanocomposites have a great potential to be a dominant coating material in a wide range of applications in the automotive, aerospace, ship-making, construction, and pharmaceutical industries. However, how to realize design sustainability of this type of nanostructured materials and how to ensure the true optimality of the product quality and process performance in coating manufacturing remain as a mountaintop area. The major challenges arise from the intrinsic multiscale nature of the material-process-product system and the need to manipulate the high levels of complexity and uncertainty in design and manufacturing processes. This research centers on the development of a comprehensive multiscale computational methodology and a computer-aided tool set that can facilitate multifunctional nanocoating design and application from novel function envisioning and idea refinement, to knowledge discovery and design solution derivation, and further to performance testing in industrial applications and life cycle analysis. The principal idea is to achieve exceptional system performance through concurrent characterization and optimization of materials, product and associated manufacturing processes covering a wide range of length and time scales. Multiscale modeling and simulation techniques ranging from microscopic molecular modeling to classical continuum modeling are seamlessly coupled. The tight integration of different methods and theories at individual scales allows the prediction of macroscopic coating performance from the fundamental molecular behavior. Goal-oriented design is also pursued by integrating additional methods for bio-inspired dynamic optimization and computational task management that can be implemented in a hierarchical computing architecture. Furthermore, multiscale systems methodologies are developed to achieve the best possible material application towards sustainable manufacturing. Automotive coating manufacturing, that involves paint spay and

Synthesis and Electrochemical Analysis of Algae Cellulose-Polypyrrole-Graphene Nanocomposite for Supercapacitor Electrode.

PubMed

Aphale, Ashish; Chattopadhyay, Aheli; Mahakalakar, Kapil; Patra, Prabir

2015-08-01

A novel nanocomposite has been developed using extracted cellulose from marine algae coated with conductive polypyrrole and graphene nanoplateletes. The nanocomposite fabricated via in situ polymerization was used as an electrode for a supercapacitor device. The nanocomposite material has been electrochemically characterized using cyclic voltammetry to test its potential to super-capacitive behavior. The specific capacitance of polypyrrole-graphene-cellulose nanocomposite as calculated from cyclic voltammetry curve is 91.5 Fg-1 at the scan rate 50 mV s-1. Transmission electron microscope images show the polymerized polypyrrole -graphene coated cellulosic nanofibers. Scanning electron microscope images reveal an interesting "necklace" like beaded morphology on the cellulose fibers. It is observed that the necklace like structure start to disintegrate with the increase in graphene concentration. The open circuit voltage of the device with polypyrrole-graphene-cellulose electrode was found to be around 225 mV and that of the polypyrrole-cellulose device is only 53 mV without graphene. The results suggest marked improvement in the performance of the nanocomposite supercapacitor device upon graphene inclusion.

Protection of dopamine towards autoxidation reaction by encapsulation into non-coated- or chitosan- or thiolated chitosan-coated-liposomes.

PubMed

Trapani, A; Mandracchia, D; Tripodo, G; Cometa, S; Cellamare, S; De Giglio, E; Klepetsanis, P; Antimisiaris, S G

2018-05-26

The aim of this work is to evaluate the potential of non-coated-, chitosan-(CS)- or chitosan-glutathione conjugate- (CS-GSH)-coated liposomes to protect the neurotransmitter Dopamine (DA) from the autoxidation reaction in neutral/alkaline conditions. This may be of interest in the development of nanotechnology-based approaches to improve Parkinson's disease treatment because decreased ROS production and reduced DA associated neurotoxicity are expected. For the mentioned purposes, DA-loaded vesicles were prepared by the Dried Reconstituted Vesicles (DRV) method, and were subsequently coated using solutions of polycations. As for the mean diameters of liposomes so prepared, the CS-GSH coated liposomes showed a significant decrease in size compared to the corresponding non-coated and CS-coated vesicles. The surface charge of DA-loaded non-coated liposomes was -10.8 mV, whereas the CS or CS-GSH coated vesicles showed a slightly positive ζ-potential. The capability of the herein studied vesicles to prevent DA autoxidation was evaluated by visual inspection, monitoring DA/lipid ratio as such and under stressed conditions. The results suggest that liposome formulations partially protect the neurotransmitter from the autoxidation reaction. In particular, the CS-GSH coated liposomes were more stable than the corresponding CS-coated and non-coated ones against the oxidative damage and were found to deliver the neurotransmitter in a sustained manner. Probably, this is due to the localization of the neurotransmitter in the core of the vesicles as indicated by XPS which confirmed the absence of the neurotransmitter on the surface of these vesicles. Copyright © 2018 Elsevier B.V. All rights reserved.

Organic/Inorganic Hybrid Polymer/Clay Nanocomposites

NASA Technical Reports Server (NTRS)

Park, Cheol; Connell, John W.; Smith, Joseph G., Jr.

2003-01-01

A novel class of polymer/clay nanocomposites has been invented in an attempt to develop transparent, lightweight, durable materials for a variety of aerospace applications. As their name suggests, polymer/ clay nanocomposites comprise organic/ inorganic hybrid polymer matrices containing platelet-shaped clay particles that have sizes of the order of a few nanometers thick and several hundred nanometers long. Partly because of their high aspect ratios and high surface areas, the clay particles, if properly dispersed in the polymer matrix at a loading level of 1 to 5 weight percent, impart unique combinations of physical and chemical properties that make these nanocomposites attractive for making films and coatings for a variety of industrial applications. Relative to the unmodified polymer, the polymer/ clay nanocomposites may exhibit improvements in strength, modulus, and toughness; tear, radiation, and fire resistance; and lower thermal expansion and permeability to gases while retaining a high degree of optical transparency.

Clay-based polymer nanocomposites: research and commercial development.

PubMed

Zeng, Q H; Yu, A B; Lu, G Q; Paul, D R

2005-10-01

This paper reviews the recent research and development of clay-based polymer nanocomposites. Clay minerals, due to their unique layered structure, rich intercalation chemistry and availability at low cost, are promising nanoparticle reinforcements for polymers to manufacture low-cost, lightweight and high performance nanocomposites. We introduce briefly the structure, properties and surface modification of clay minerals, followed by the processing and characterization techniques of polymer nanocomposites. The enhanced and novel properties of such nanocomposites are then discussed, including mechanical, thermal, barrier, electrical conductivity, biodegradability among others. In addition, their available commercial and potential applications in automotive, packaging, coating and pigment, electrical materials, and in particular biomedical fields are highlighted. Finally, the challenges for the future are discussed in terms of processing, characterization and the mechanisms governing the behaviour of these advanced materials.

Bondable Stainless Surface Coats Protect Against Rust

NASA Technical Reports Server (NTRS)

Davis, G. D.; Shaffer, D. K.; Clearfield, H. M.; Nagle, D.; Groff, G.

1995-01-01

Report describes tests conducted to assess use of bondable stainless surface (BOSS) coating materials to protect steel cases of solid-fuel rocket motors against corrosion and to provide surface microstructure and chemistry suitable for bonding to insulating material. Eliminates need to cover cases with grease to prevent corrosion and degreasing immediately prior to use.

Structure and properties of polyaniline nanocomposite coatings containing gold nanoparticles formed by low-energy electron beam deposition

NASA Astrophysics Data System (ADS)

Wang, Surui; Rogachev, A. A.; Yarmolenko, M. A.; Rogachev, A. V.; Xiaohong, Jiang; Gaur, M. S.; Luchnikov, P. A.; Galtseva, O. V.; Chizhik, S. A.

2018-01-01

Highly ordered conductive polyaniline (PANI) coatings containing gold nanoparticles were prepared by low-energy electron beam deposition method, with emeraldine base and chloroauric acid used as target materials. The molecular and chemical structure of the layers was studied by Fourier transform infrared, Raman, UV-vis and X-ray photoelectron spectroscopy. The morphology of the coatings was investigated by atomic force and transmission electron microscopy. Conductive properties were obtained by impedance spectroscopy method and scanning spreading resistance microscopy mode at the micro- and nanoscale. It was found that the emeraldine base layers formed from the products of electron-beam dispersion have extended, non-conductive polymer chains with partially reduced structure, with the ratio of imine and amine groups equal to 0.54. In case of electron-beam dispersion of the emeraldine base and chloroauric acid, a protoemeraldine structure is formed with conductivity 0.1 S/cm. The doping of this structure was carried out due to hydrochloric acid vapor and gold nanoparticles formed by decomposition of chloroauric acid, which have a narrow size distribution, with the most probable diameter about 40 nm. These gold nanoparticles improve the conductivity of the thin layers of PANI + Au composite, promoting intra- and intermolecular charge transfer of the PANI macromolecules aligned along the coating surface both at direct and alternating voltage. The proposed deposition method of highly oriented, conductive nanocomposite PANI-based coatings may be used in the direct formation of functional layers on conductive and non-conductive substrates.

Synthesis of copper coated carbon nanotubes for aluminium matrix composites

NASA Astrophysics Data System (ADS)

Maqbool, Adnan; Khalid, F. Ahmad; Hussain, M. Asif; Bakhsh, Nabi

2014-06-01

In this investigation copper coated carbon nanotubes (CNTs) were prepared to enhance the interfacial bonding between CNTs and aluminum matrix by the molecular-level mixing process. In optimized plating bath of (1:1) by wt. CNT with Cu, thickness of coated CNTs is reduced to 100 nm to promote uniform distribution of Cu nanoparticle on the surface of pretreated CNTs. The mixing of CNTs was accomplished by ultrasonication and ball milling. Scanning electron microscope analysis revealed the homogenous dispersion of Cu-coated CNTs in nanocomposites samples compared to the uncoated CNTs. The samples were pressureless sintered under vacuum. The densification increased with the increase in the CNTs content and is more pronounced in Cu-coated CNT nanocomposites.

Poly(hydroxyalkanoate)s-Based Hydrophobic Coatings for the Protection of Stone in Cultural Heritage

PubMed Central

Andreotti, Serena; Fabbri, Paola

2018-01-01

Reversibility is a mandatory requirement for materials used in heritage conservation, including hydrophobic protectives. Nevertheless, current protectives for stone are not actually reversible as they remain on the surfaces for a long time after their hydrophobicity is lost and can hardly be removed. Ineffective and aged coatings may jeopardise the stone re-treatability and further conservation interventions. This paper aims at investigating the performance of PHAs-based coatings for stone protection, their main potential being the ‘reversibility by biodegradation’ once water repellency ended. The biopolymer coatings were applied to three different kinds of stone, representative of lithotypes used in historic architecture: sandstone, limestone and marble. Spray, poultice and dip-coating were tested as coating techniques. The effectiveness and compatibility of the protectives were evaluated in terms of capillary water absorption, static and dynamic contact angles, water vapour diffusion, colour alteration and surface morphology. The stones’ wettability after application of two commercial protectives was investigated too, for comparison. Finally, samples were subjected to artificial ageing to investigate their solar light stability. Promising results in terms of efficacy and compatibility were obtained, although the PHAs-based formulations developed here still need improvement for increased durability and on-site applicability. PMID:29361721

Galvanic Liquid Applied Coating System for Protection of Embedded Steel Surfaces from Corrosion

NASA Technical Reports Server (NTRS)

Curran, Joseph; MacDowell, Louis; Voska, N. (Technical Monitor)

2002-01-01

The corrosion of reinforcing steel in concrete is an insidious problem for the Kennedy Space Center, government agencies, and the general public. Existing corrosion protection systems on the market are costly, complex, and time-consuming to install, require continuous maintenance and monitoring, and require specialized skills for installation. NASA's galvanic liquid-applied coating offers companies the ability to conveniently protect embedded steel rebar surfaces from corrosion. Liquid-applied inorganic galvanic coating contains one ore more of the following metallic particles: magnesium, zinc, or indium and may contain moisture attracting compounds that facilitate the protection process. The coating is applied to the outer surface of reinforced concrete so that electrical current is established between metallic particles and surfaces of embedded steel rebar; and electric (ionic) current is responsible for providing the necessary cathodic protection for embedded rebar surfaces.

Development and Application of HVOF Sprayed Spinel Protective Coating for SOFC Interconnects

NASA Astrophysics Data System (ADS)

Thomann, O.; Pihlatie, M.; Rautanen, M.; Himanen, O.; Lagerbom, J.; Mäkinen, M.; Varis, T.; Suhonen, T.; Kiviaho, J.

2013-06-01

Protective coatings are needed for metallic interconnects used in solid oxide fuel cell (SOFC) stacks to prevent excessive high-temperature oxidation and evaporation of chromium species. These phenomena affect the lifetime of the stacks by increasing the area-specific resistance (ASR) and poisoning of the cathode. Protective MnCo2O4 and MnCo1.8Fe0.2O4 coatings were applied on ferritic steel interconnect material (Crofer 22 APU) by high velocity oxy fuel spraying. The substrate-coating systems were tested in long-term exposure tests to investigate their high-temperature oxidation behavior. Additionally, the ASRs were measured at 700 °C for 1000 h. Finally, a real coated interconnect was used in a SOFC single-cell stack for 6000 h. Post-mortem analysis was carried out with scanning electron microscopy. The deposited coatings reduced significantly the oxidation of the metal, exhibited low and stable ASR and reduced effectively the migration of chromium.

Preparation of ecofriendly UV-protective food packaging material by starch/TiO2 bio-nanocomposite: Characterization.

PubMed

Goudarzi, Vahid; Shahabi-Ghahfarrokhi, Iman; Babaei-Ghazvini, Amin

2017-02-01

In this study, ecofriendly starch/TiO 2 bio-nanocomposites were produced using with different nano-TiO 2 (TiO 2 ) content (1, 3, and 5 (wt%)). Physical, mechanical, thermal, water-vapor permeability (WVP) properties and UV transmittance were investigated. Our results showed that the increasing TiO 2 content increased the hydrophobicity of starch/TiO 2 films. WVP of the bio-nanocomposites was reduced, simultaneously. With increasing TiO 2 content, tensile strength and Young's modulus of the film specimens were reduced while elongation at break and tensile energy to break were increased. The thermal properties of specimens showed that glass transition temperature of the films increased but melting point of the specimen films was decreased by increasing TiO 2 content. Scanning electron microscopy observations demonstrated, the most of films' physical properties were in relation to their microstructures. The starch/TiO 2 nanocomposites effectively protect goods against UV light, and could potentially be applied as UV-shielding packaging materials. Copyright © 2016 Elsevier B.V. All rights reserved.

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

NASA Technical Reports Server (NTRS)

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

1981-01-01

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

Ion-plasma protective coatings for gas-turbine engine blades

NASA Astrophysics Data System (ADS)

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

2007-10-01

Evaporated, diffusion, and evaporation—diffusion protective and hardening multicomponent ionplasma coatings for turbine and compressor blades and other gas-turbine engine parts are considered. The processes of ion surface treatment (ion etching and ion saturation of a surface in the metallic plasma of a vacuum arc) and commercial equipment for the deposition of coatings and ion surface treatment are analyzed. The specific features of the ion-plasma coatings deposited from the metallic plasma of a vacuum arc are described, and the effect of the ion energy on the phase composition of the coatings and the processes occurring in the surface layer of an article to be treated are discussed. Some properties of ion-plasma coatings designed for various purposes are presented. The ion surface saturation of articles made from structural materials is shown to change the structural and phase states of their surfaces and, correspondingly, the related properties of these materials (i.e., their heat resistance, corrosion resistance, fatigue strength, and so on).

Using Layer-by-Layer Coating and Nanocomposite Technologies to Improve the Barrier Properties of Polymeric Materials

NASA Astrophysics Data System (ADS)

Soltani, Iman

Means for improving barrier properties of polymers against gases, particularly for promoting their applications as packaging materials, are divided into surface coating and embedding nanoparticles in the bulk of the polymeric membranes. In this research, we mainly investigated improvement in barrier properties of polymers against oxygen and carbon dioxide, through layer-by-layer (LBL) coating and bulk nanocomposite methods. Initially, we studied the morphology of layer-by-layer assemblies comprising alternating layers of polyelectrolyte (PE) and natural montmorillonite (MMT) platelets, where polyethyleneterephthalate ionomer was used as our proposed alternative PE, to be compared with already examined polyethyleneimine. For both investigated PEs, while microscopic images showed the formation of tortuous networks of galleries between subsequent layers of oriented clay platelets parallel to the substrate surface, x-ray diffractometry (XRD) traces pointed to the intercalation of PE layers between clay platelets. As a confirmation of forming tortuous networks between oriented and high aspect ratio clay platelets to increase the path length of diffusing gas species dramatically, LBL-coated polystyrene-based membranes demonstrated pronounced decreases in permeability of oxygen and carbon dioxide (e.g. about the scale of 500 times decrease in permeability, with only five cycles of bilayer deposition). Before LBL deposition, the surface of the hydrophobic polymeric substrate was pretreated with oxygen plasma to improve its interaction with the coating. In the next study, previously LBL-coated samples were melt pressed in a cyclic manner to embed and to crush the coating inside the polystyrene-based matrix, aiming the exfoliated polymer-clay nanocomposites. The morphological investigations by transmission electron microscopy (TEM) revealed the tortuous internal structure of crushed LBL assemblies' portions, mainly comprising swollen intercalated stacks of clay, as well as

Nondestructive evaluation of protective coatings for the conservation of industrial monuments

NASA Astrophysics Data System (ADS)

Welp, Hubert; Lenz, Marcel; Mazzon, Cristian; Dillmann, Christopher; Gerhardt, Nils C.; Prange, Michael; Hofmann, Martin R.

2017-07-01

For the conservation of cultural monuments standard anti-corrosion coatings are not applicable because the historical character of the objects would be lost. Alternative transparent coatings have to be evaluated and monitored nondestructively with respect to their effectiveness in protecting metal surfaces. We demonstrate that Optical Coherence Tomography (OCT) can be an alternative to the currently used method of Electrochemical Impedance Spectroscopy (EIS) for the characterization of coating defects and corrosion processes.

"Snow White" Coating Protects SpaceX Dragon's Trunk Against Rigors of Space

NASA Technical Reports Server (NTRS)

McMahan, Tracy

2013-01-01

He described it as "snow white." But NASA astronaut Don Pettit was not referring to the popular children's fairy tale. Rather, he was talking about the white coating of the Space Exploration Technologies Corp. (SpaceX) Dragon spacecraft that reflected from the International Space Station s light. As it approached the station for the first time in May 2012, the Dragon s trunk might have been described as the "fairest of them all," for its pristine coating, allowing Pettit to clearly see to maneuver the robotic arm to grab the Dragon for a successful nighttime berthing. This protective thermal control coating, developed by Alion Science and Technology Corp., based in McLean, Va., made its bright appearance again with the March 1 launch of SpaceX's second commercial resupply mission. Named Z-93C55, the coating was applied to the cargo portion of the Dragon to protect it from the rigors of space. "For decades, Alion has produced coatings to protect against the rigors of space," said Michael Kenny, senior chemist with Alion. "As space missions evolved, there was a growing need to dissipate electrical charges that build up on the exteriors of spacecraft, or there could be damage to the spacecraft s electronics. Alion's research led us to develop materials that would meet this goal while also providing thermal controls. The outcome of this research was Alion's proprietary Z-93C55 coating."

Leveling coatings for reducing the atomic oxygen defect density in protected graphite fiber epoxy composites

NASA Astrophysics Data System (ADS)

Jaworske, D. A.; Degroh, Kim K.; Podojil, G.; McCollum, T.; Anzic, J.

1992-11-01

Pinholes or other defect sites in a protective oxide coating provide pathways for atomic oxygen in low Earth orbit to reach underlying material. One concept of enhancing the lifetime of materials in low Earth orbit is to apply a leveling coating to the material prior to applying any reflective and protective coatings. Using a surface tension leveling coating concept, a low viscosity epoxy was applied to the surface of several composite coupons. A protective layer of 1000 A of SiO2 was deposited on top of the leveling coating, and the coupons were exposed to an atomic oxygen environment in a plasma asher. Pinhole populations per unit area were estimated by counting the number of undercut sites observed by scanning electron microscopy. Defect density values of 180,000 defects/sq cm were reduced to about 1000 defects/sq cm as a result of the applied leveling coating. These improvements occur at a mass penalty of about 2.5 mg/sq cm.

Leveling coatings for reducing the atomic oxygen defect density in protected graphite fiber epoxy composites

NASA Technical Reports Server (NTRS)

Jaworske, D. A.; Degroh, K. K.; Podojil, G.; Mccollum, T.; Anzic, J.

1992-01-01

Pinholes or other defect sites in a protective oxide coating provide pathways for atomic oxygen in low Earth orbit to reach underlying material. One concept for enhancing the lifetime of materials in low Earth orbits is to apply a leveling coating to the material prior to applying any reflective and protective coatings. Using a surface tension leveling coating concept, a low viscosity epoxy was applied to the surface of several composite coupons. A protective layer of 1000 A of SiO2 was deposited on top of the leveling coating, and the coupons were exposed to an atomic oxygen environment in a plasma asher. Pinhole populations per unit area were estimated by counting the number of undercut sites observed by scanning electron microscopy. Defect density values of 180,000 defects/sq cm were reduced to about 1000 defects/sq cm as a result of the applied leveling coating. These improvements occur at a mass penalty of about 2.5 mg/sq cm.

Leveling coatings for reducing the atomic oxygen defect density in protected graphite fiber epoxy composites

NASA Technical Reports Server (NTRS)

Jaworske, D. A.; Degroh, Kim K.; Podojil, G.; Mccollum, T.; Anzic, J.

1992-01-01

Pinholes or other defect sites in a protective oxide coating provide pathways for atomic oxygen in low Earth orbit to reach underlying material. One concept of enhancing the lifetime of materials in low Earth orbit is to apply a leveling coating to the material prior to applying any reflective and protective coatings. Using a surface tension leveling coating concept, a low viscosity epoxy was applied to the surface of several composite coupons. A protective layer of 1000 A of SiO2 was deposited on top of the leveling coating, and the coupons were exposed to an atomic oxygen environment in a plasma asher. Pinhole populations per unit area were estimated by counting the number of undercut sites observed by scanning electron microscopy. Defect density values of 180,000 defects/sq cm were reduced to about 1000 defects/sq cm as a result of the applied leveling coating. These improvements occur at a mass penalty of about 2.5 mg/sq cm.

Alternatives to SiOx for protective scan mirror coatings in remote sensing instruments

NASA Astrophysics Data System (ADS)

MacDonald, Michael E.

1999-09-01

Mirrors in remote sensing instruments require durable dielectric coatings, both to prevent oxidation of the reflective surface and to protect it during cleaning. IR absorption bands within widely-used SiOx coatings produce scene radiance and instrument background variations as a function of scan mirror angle which motivate the search for possible substitute materials. In this work several candidate coatings are evaluated including CeF3, HfO2, MgF2 SrF2, and Y2O3. This evaluation consists of reflectance, adhesion, and durability measurements of mirrors with an aluminum reflective surface over-coated with these materials. S-polarized and P- polarized reflectance measurements are presented between 2 and 20 micrometers for incidence angles between 40 and 50 degrees. This angular range is sufficient to scan the earth disk from geostationary orbit. Additional measurements at 45 degrees incidence are presented between 2 and 55 micrometers , covering the IR wavelength range of interest for earth radiation budget sensors. Comparisons are drawn with measurements of scan- mirror witness samples from the imaging and sounding instruments used in the Geostationary Operational Environmental Satellite (GOES). These witness samples exhibit reflectance variations arising from IR absorption bands in the SiOx protective coatings used in these mirrors. The spectral characteristics of several of the alternate materials are found to be quite attractive, however durable coatings of some of these materials require elevated deposition temperature which are incompatible with the nickel-coated beryllium scan mirror substrate construction used in GOES. This work present the achievable reflectance and durability of these alternate dielectric protective coatings at the deposition temperature constraints imposed by the scan mirror substrate. The prospects for substituting one of these coatings for SiOx are evaluated, and contrasted with the capability of radiometric calibration techniques to deal

Simulation and Design of Nanocomposite for Application in Ballistic Protection

DTIC Science & Technology

2008-12-01

diene terpolymer ( EPDM ) nanocomposites with organo- montmorillonite (OMMT). It was found that the tensile modulus can be increased by 60% and...Y. D. and Li, W., 2005: Morphology and characterization of clay-reinforced EPDM nanocomposites, J. Comp. Mat., 39, 745- 754. [3] Avila, A. F

Sliding friction of nanocomposite WC1-x/C coatings: transfer film and its influence on tribology.

PubMed

Liu, Y; Gubisch, M; Spiess, L; Schaefer, J A

2009-06-01

The transfer film on steel spheres formed in reciprocating sliding against nanocomposite coatings based on nanocrystalline WC1-x in amorphous carbon matrix is characterized and correlated with the tribological properties measured by a precision microtribometer. With the presence of transfer film, a coefficient of friction approximately 0.13 and a depth wear rate approximately 0.35 x 10(-10) m/N.Pass were obtained. The central zone of the transfer film covering approximately 25% of the Hertz contact area is intact while cracks and wear debris are found in the vast peripheral area. It is also heavily oxidized due to the absence of carbon, which is located at the peripherals and acts as lubricants. We propose that the oxidation of WC and adhesion of the oxides to the surface of sphere is the main mechanism for the buildup of the transfer films. With the thickening of the film, the internal stress increases. Under the shear stress, spalling and cracking of the transfer film take place. The overall tribological performance of the coatings is therefore a competing process of buildup and spalling of transfer films.

Electrodeposition of Ni(OH)2 reinforced polyaniline coating for corrosion protection of 304 stainless steel

NASA Astrophysics Data System (ADS)

Jiang, Li; Syed, Junaid Ali; Gao, Yangzhi; Lu, Hongbin; Meng, Xiangkang

2018-05-01

In the present paper, polyaniline (PANI) coating was electropolymerized in the presence of phosphoric acid with subsequent deposition of Ni(OH)2 particles. The Ni(OH)2 reinforced PANI coating significantly enhances the corrosion resistance of 304 stainless steel (304SS) in comparison with the pristine PANI coating. The galvanostatically deposited Ni(OH)2 particles fill the pores of the pristine PANI coating and improves the coatings hydrophobicity which decreases the diffusion of aggressive media. Importantly, the Rp values of Ni(OH)2 reinforced PANI coating is much higher than that of pristine PANI coating and the Ni(OH)2 reinforced PANI coating presents a long-term anti-corrosive ability (360 h) in 3.5 wt% NaCl solution. The prolonged corrosion protection of Ni(OH)2 reinforced PANI coating is attributed to the improved physical barrier as well as the facile formation of passive oxide film that sustain the anodic protection of the coating.

Polyaniline-carboxymethyl cellulose nanocomposite for cholesterol detection.

PubMed

Barik, Abdul; Solanki, Pratima R; Kaushik, Ajeet; Ali, Azahar; Pandey, M K; Kim, C G; Malhotra, B D

2010-10-01

Cholesterol oxidase (ChOx) has been covalently immobilized onto polyaniline-carboxymethyl cellulose (PANI-CMC) nanocomposite film deposited onto indium-tin-oxide (ITO) coated glass plate using glutaraldehyde as a cross-linker. Fourier transform infrared (FTIR) spectroscopic and electrochemical studies have been used to characterize the PANI-CMC/ITO nanocomposite electrode and ChOx/PANI-CMC/ITO bioelectrode. Scanning electron microscopy (SEM) studies reveal the formation of PANI-CMC nanocomposite fibers of size approximately 150 nm in diameter. The ChOx/PANI-CMC/ITO bioelectrode exhibits linearity as 0.5-22 mM, detection limit as 1.31 mM, sensitivity as 0.14 mA/mM cm2, response time as 10 s and shelf-life of about 10 weeks when bioelectrode is stored at 4 degrees C. The low value of Michaelis-Menten constant (K(m)) obtained as 2.71 mM reveals high affinity of immobilized ChOx for PANI-CMC/ITO nanocomposite electrode.

Diamondlike carbon protective coatings for optical windows

NASA Technical Reports Server (NTRS)

Swec, Diane M.; Mirtich, Michael J.

1989-01-01

Diamondlike carbon (DLC) films were deposited on infrared transmitting optical windows and were evaluated as protective coatings for these windows exposed to particle and rain erosion. The DLC films were deposited on zinc selenide (ZnSe) and zinc sulfide (ZnS) by three different ion beam methods: (1) sputter deposition from a carbon target using an 8-cm argon ion source; (2) direct deposition by a 30-cm hollow cathode ion source with hydrocarbon gas in argon; and (3) dual beam direct deposition by the 30-cm hollow cathode ion source and an 8-cm argon ion source. In an attempt to improve the adherence of the DLC films on ZnSc and ZnS, ion beam cleaning, ion implantation with helium and neon ions, or sputter deposition of a thin, ion beam intermediate coating was employed prior to deposition of the DLC film. The protection that the DLC films afforded the windows from particle and rain erosion was evaluated, along with the hydrogen content, adherence, intrinsic stress, and infrared transmittance of the films. Because of the elevated stress levels in the ion beam sputtered DLC films and in those ion beam deposited with butane, films thicker than 0.1 micron and with good adherence on ZnS and ZnSe could not be generated. An intermediate coating of germanium successfully allowed the DLC films to remain adherent to the optical windows and caused only negligible reduction in the specular transmittance of the ZnS and ZnSe at 10 microns.

Thermal certification tests of Orbiter Thermal Protection System tiles coated with KSC coating slurries

NASA Technical Reports Server (NTRS)

Milhoan, James D.; Pham, Vuong T.; Sherborne, William D.

1993-01-01

Thermal tests of Orbiter thermal protection system (TPS) tiles, which were coated with borosilicate glass slurries fabricated at Kennedy Space Center (KSC), were performed in the Radiant Heat Test Facility and the Atmospheric Reentry Materials & Structures Evaluation Facility at Johnson Space Center to verify tile coating integrity after exposure to multiple entry simulation cycles in both radiant and convective heating environments. Eight high temperature reusable surface insulation (HRSI) tiles and six low temperature reusable surface insulation (LRSI) tiles were subjected to 25 cycles of radiant heat at peaked surface temperatures of 2300 F and 1200 F, respectively. For the LRSI tiles, an additional cycle at peaked surface temperature of 2100 F was performed. There was no coating crack on any of the HRSI specimens. However, there were eight small coating cracks (less than 2 inches long) on two of the six LRSI tiles on the 26th cycle. There was practically no change on the surface reflectivity, physical dimensions, or weight of any of the test specimens. There was no observable thermal-chemical degradation of the coating either. For the convective heat test, eight HRSI tiles were tested for five cycles at a surface temperature of 2300 F. There was no thermal-induced coating crack on any of the test specimens, almost no change on the surface reflectivity, and no observable thermal-chemical degradation with an exception of minor slumping of the coating under painted TPS identification numbers. The tests demonstrated that KSC's TPS slurries and coating processes meet the Orbiter's thermal specification requirements.

Flexible Transparent Supercapacitors Based on Hierarchical Nanocomposite Films.

PubMed

Chen, Fanhong; Wan, Pengbo; Xu, Haijun; Sun, Xiaoming

2017-05-31

Flexible transparent electronic devices have recently gained immense popularity in smart wearable electronics and touch screen devices, which accelerates the development of the portable power sources with reliable flexibility, robust transparency and integration to couple these electronic devices. For potentially coupled as energy storage modules in various flexible, transparent and portable electronics, the flexible transparent supercapacitors are developed and assembled from hierarchical nanocomposite films of reduced graphene oxide (rGO) and aligned polyaniline (PANI) nanoarrays upon their synergistic advantages. The nanocomposite films are fabricated from in situ PANI nanoarrays preparation in a blended solution of aniline monomers and rGO onto the flexible, transparent, and stably conducting film (FTCF) substrate, which is obtained by coating silver nanowires (Ag NWs) layer with Meyer rod and then coating of rGO layer on polyethylene terephthalate (PET) substrate. Optimization of the transparency, the specific capacitance, and the flexibility resulted in the obtained all-solid state nanocomposite supercapacitors exhibiting enhanced capacitance performance, good cycling stability, excellent flexibility, and superior transparency. It provides promising application prospects for exploiting flexible, low-cost, transparent, and high-performance energy storage devices to be coupled into various flexible, transparent, and wearable electronic devices.

Double coating protection of Nd-Fe-B magnets: Intergranular phosphating treatment and copper plating

NASA Astrophysics Data System (ADS)

Zheng, Jingwu; Chen, Haibo; Qiao, Liang; Lin, Min; Jiang, Liqiang; Che, Shenglei; Hu, Yangwu

2014-12-01

In this work, a double coating protection technique of phosphating treatment and copper plating was made to improve the corrosion resistance of sintered Nd-Fe-B magnets. In other words, the intergranular region of sintered Nd-Fe-B is allowed to generate passive phosphate conversion coating through phosphating treatment, followed by the copper coating on the surface of sintered Nd-Fe-B. The morphology and corrosion resistance of the phosphated sintered Nd-Fe-B were observed using SEM and electrochemical method respectively. The phosphate conversion coating was formed more preferably on the intergranular region of sintered Nd-Fe-B than on the main crystal region; just after a short time of phosphating treatment, the intergranular region of sintered Nd-Fe-B has been covered by the phosphate conversion coating and the corrosion resistance is significantly improved. With the synergistic protection of the intergranular phosphorization and the followed copper electrodeposition, the corrosion resistance of the sintered Nd-Fe-B is significantly better than that with a single phosphate film or single plating protection.

Characterization of Hybrid Epoxy Nanocomposites

PubMed Central

Simcha, Shelly; Dotan, Ana; Kenig, Samuel; Dodiuk, Hanna

2012-01-01

This study focused on the effect of Multi Wall Carbon Nanotubes (MWCNT) content and its surface treatment on thermo-mechanical properties of epoxy nanocomposites. MWCNTs were surface treated and incorporated into two epoxy systems. MWCNT's surface treatments were based on: (a) Titania coating obtained by sol-gel process and (b) a nonionic surfactant. Thermo-mechanical properties improvement was obtained following incorporation of treated MWCNT. It was noticed that small amounts of titania coated MWCNT (0.05 wt %) led to an increase in the glass transition temperature and stiffness. The best performance was achieved adding 0.3 wt % titania coated MWCNT where an increase of 10 °C in the glass transition temperature and 30% in storage modulus were obtained. PMID:28348313

Parylene coatings on stainless steel 316L surface for medical applications--mechanical and protective properties.

PubMed

Cieślik, Monika; Kot, Marcin; Reczyński, Witold; Engvall, Klas; Rakowski, Wiesław; Kotarba, Andrzej

2012-01-01

The mechanical and protective properties of parylene N and C coatings (2-20 μm) on stainless steel 316L implant materials were investigated. The coatings were characterized by scanning electron and confocal microscopes, microindentation and scratch tests, whereas their protective properties were evaluated in terms of quenching metal ion release from stainless steel to simulated body fluid (Hanks solution). The obtained results revealed that for parylene C coatings, the critical load for initial cracks is 3-5 times higher and the total metal ions release is reduced 3 times more efficiently compared to parylene N. It was thus concluded that parylene C exhibits superior mechanical and protective properties for application as a micrometer coating material for stainless steel implants. Copyright © 2011 Elsevier B.V. All rights reserved.

Effect of protective coating on microhardness of a new glass ionomer cement: Nanofilled coating versus unfilled resin.

PubMed

Faraji, Foad; Heshmat, Haleh; Banava, Sepideh

2017-01-01

EQUIA TM is a new gastrointestinal (GI) system with high compressive strength, surface microhardness (MH), and fluoride release potential. This in vitro study aimed to assess the effect of aging and type of protective coating on the MH of EQUIA TM GI cement. A total of 30 disc-shaped specimens measuring 9 mm in diameter and 2 mm in thickness were fabricated of EQUIA TM GI and divided into three groups of G-Coat nanofilled coating (a), no coating (b) and margin bond (c). The Vickers MH value of specimens was measured before (baseline) and at 3 and 6 months after water storage. Data were analyzed using repeated measures ANOVA. Group B had significantly higher MH than the other two groups at baseline. Both G-Coat and margin bond increased the surface MH of GI at 3 and 6 months. The MH values of G-Coat and margin bond groups did not significantly increase or decrease between 3 and 6 months. The increase in MH was greater in the G-Coat compared to the margin bond group in the long-term. Clinically, margin bond may be a suitable alternative when G-Coat is not available.

Flexible fluoropolymer filled protective coatings

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Mirtich, Michael J.; Sovey, James S.; Nahra, Henry; Rutledge, Sharon K.

1991-01-01

Metal oxide films such as SiO2 are known to provide an effective barrier to the transport of moisture as well as gaseous species through polymeric films. Such thin film coatings have a tendency to crack upon flexure of the polymeric substrate. Sputter co-deposition of SiO2 with 4 to 15 percent fluoropolymers was demonstrated to produce thin films with glass-like barrier properties that have significant increases in strain to failure over pure glass films which improves their tolerance to flexure on polymeric substrates. Deposition techniques capable of producing these films on polymeric substrates are suitable for durable food packaging and oxidation/corrosion protection applications.

Smart window coating based on F-TiO2-KxWO3 nanocomposites with heat shielding, ultraviolet isolating, hydrophilic and photocatalytic performance

PubMed Central

Liu, Tongyao; Liu, Bin; Wang, Jing; Yang, Linfen; Ma, Xinlong; Li, Hao; Zhang, Yihong; Yin, Shu; Sato, Tsugio; Sekino, Tohru; Wang, Yuhua

2016-01-01

A series of smart window coated multifunctional NIR shielding-photocatalytic films were fabricated successfully through KxWO3 and F-TiO2 in a low-cost and environmentally friendly process. Based on the synergistic effect of KxWO3 and F-TiO2, the optimal proportion of KxWO3 to F-TiO2 was investigated and the FT/2KWO nanocomposite film exhibited strong near-infrared, ultraviolet light shielding ability, good visible light transmittance, high photocatalytic activity and excellent hydrophilic capacity. This film exhibited better thermal insulation capacity than ITO and higher photocatalytic activity than P25. Meanwhile, the excellent stability of this film was examined by the cycle photocatalytic degradation and thermal insulation experiments. Overall, this work is expected to provide a possibility in integrating KxWO3 with F-TiO2, so as to obtain a multifunctional NIR shielding-photocatalytic nanocomposite film in helping solve the energy crisis and deteriorating environmental issues. PMID:27265778

Fabrication of Calcium Phosphate-Based Nanocomposites Incorporating DNA Origami, Gold Nanorods, and Anticancer Drugs for Biomedical Applications.

PubMed

Zhang, Hongbo; Qu, Xiangmeng; Chen, Hong; Kong, Haixin; Ding, Ruihua; Chen, Dong; Zhang, Xu; Pei, Hao; Santos, Hélder A; Hai, Mingtan; Weitz, David A

2017-10-01

DNA origami is designed by folding DNA strands at the nanoscale with arbitrary control. Due to its inherent biological nature, DNA origami is used in drug delivery for enhancement of synergism and multidrug resistance inhibition, cancer diagnosis, and many other biomedical applications, where it shows great potential. However, the inherent instability and low payload capacity of DNA origami restrict its biomedical applications. Here, this paper reports the fabrication of an advanced biocompatible nano-in-nanocomposite, which protects DNA origami from degradation and facilities drug loading. The DNA origami, gold nanorods, and molecular targeted drugs are co-incorporated into pH responsive calcium phosphate [Ca 3 (PO 4 ) 2 ] nanoparticles. Subsequently, a thin layer of phospholipid is coated onto the Ca 3 (PO 4 ) 2 nanoparticle to offer better biocompatibility. The fabricated nanocomposite shows high drug loading capacity, good biocompatibility, and a photothermal and pH-responsive payload release profile and it fully protects DNA origami from degradation. The codelivery of DNA origami with cancer drugs synergistically induces cancer cell apoptosis, reduces the multidrug resistance, and enhances the targeted killing efficiency toward human epidermal growth factor receptor 2 positive cells. This nanocomposite is foreseen to open new horizons for a variety of clinical and biomedical applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermal Management Coating As Thermal Protection System for Space Transportation System

NASA Technical Reports Server (NTRS)

Kaul, Raj; Stuckey, C. Irvin

2003-01-01

This paper presents viewgraphs on the development of a non-ablative thermal management coating used as the thermal protection system material for space shuttle rocket boosters and other launch vehicles. The topics include: 1) Coating Study; 2) Aerothermal Testing; 3) Preconditioning Environments; 4) Test Observations; 5) Lightning Strike Test Panel; 6) Test Panel After Impact Testing; 7) Thermal Testing; and 8) Mechanical Testing.

Investigation on Curcumin nanocomposite for wound dressing.

PubMed

Venkatasubbu, G Devanand; Anusuya, T

2017-05-01

Curcuma longa (turmeric) has a long history of use in medicine as a treatment for inflammatory conditions. The primary active constituent of turmeric and the one responsible for its vibrant yellow color is curcumin. Curcumin is used for treatment of wound and inflammation. It had antimicrobial and antioxidant property. It has low intrinsic toxicity and magnificent properties like with comparatively lesser side-effects. Cotton cloth is one of the most successful wound dressings which utilize the intrinsic properties of cotton fibers. Modern wound dressings, however, require other properties such as antibacterial and moisture maintaining capabilities. In this study, conventional cotton cloth was coated with Curcumin composite for achieving modern wound dressing properties. Curcumin nanocomposite is characterized. The results show that coated cotton cloth with Curcumin nanocomposite has increased drying time (74%) and water absorbency (50%). Furthermore, they show antibacterial efficiency against bacterial species present in wounds. Copyright © 2017 Elsevier B.V. All rights reserved.

Low cost sol-gel derived SiC-SiO2 nanocomposite as anti reflection layer for enhanced performance of crystalline silicon solar cells

NASA Astrophysics Data System (ADS)

Jannat, Azmira; Lee, Woojin; Akhtar, M. Shaheer; Li, Zhen Yu; Yang, O.-Bong

2016-04-01

This paper describes the preparation, characterizations and the antireflection (AR) coating application in crystalline silicon solar cells of sol-gel derived SiC-SiO2 nanocomposite. The prepared SiC-SiO2 nanocomposite was effectively applied as AR layer on p-type Si-wafer via two step processes, where the sol-gel of precursor solution was first coated on p-type Si-wafer using spin coating at 2000 rpm and then subjected to annealing at 450 °C for 1 h. The crystalline, and structural observations revealed the existence of SiC and SiO2 phases, which noticeably confirmed the formation of SiC-SiO2 nanocomposite. The SiC-SiO2 layer on Si solar cells was found to be an excellent AR coating, exhibiting the low reflectance of 7.08% at wavelengths ranging from 400 to 1000 nm. The fabricated crystalline Si solar cell with SiC-SiO2 nanocomposite AR coating showed comparable power conversion efficiency of 16.99% to the conventional SixNx AR coated Si solar cell. New and effective sol-gel derived SiC-SiO2 AR layer would offer a promising technique to produce high performance Si solar cells with low-cost.

Ceria-containing uncoated and coated hydroxyapatite-based galantamine nanocomposites for formidable treatment of Alzheimer's disease in ovariectomized albino-rat model.

PubMed

Wahba, Sanaa M R; Darwish, Atef S; Kamal, Sara M

2016-08-01

This paper upraises delivery and therapeutic actions of galantamine drug (GAL) against Alzheimer's disease (AD) in rat brain through attaching GAL to ceria-containing hydroxyapatite (GAL@Ce-HAp) as well ceria-containing carboxymethyl chitosan-coated hydroxyapatite (GAL@Ce-HAp/CMC) nanocomposites. Physicochemical features of such nanocomposites were analyzed by XRD, FT-IR, Raman spectroscopy, UV-vis spectrophotometer, N2-BET, DLS, zeta-potential measurements, SEM, and HR-TEM. Limited interactions were observed in GAL@Ce-HAp with prevailed existence of dispersed negatively charged rod-like particles conjugated with ceria nanodots. On contrary, GAL@Ce-HAp/CMC was well-structured developing aggregates of uncharged tetragonal-shaped particles laden with accession of ceria quantum dots. Such nanocomposites were i.p. injected into ovariectomized AD albino-rats at galantamine dose of 2.5mg/kg/day for one month, then brain tissues were collected for biochemical and histological tests. GAL@Ce-HAp adopted as a promising candidate for AD curativeness, whereas oxidative stress markers were successfully upregulated, degenerated neurons in hippocampal and cerebral tissues were wholly recovered and Aβ-plaques were vanished. Also, optimizable in-vitro release for GAL and nanoceria were displayed from GAL@Ce-HAp, while delayed in-vitro release for those species were developed from GAL@Ce-HAp/CMC. This proof of concept work allow futuristic omnipotency of rod-like hydroxyapatite particles for selective delivery of GAL and nanoceria to AD affected brain areas. Copyright © 2016 Elsevier B.V. All rights reserved.

Co-precipitation synthesis of nano-composites consists of zinc and tin oxides coatings on glass with enhanced photocatalytic activity on degradation of Reactive Blue 160 KE2B.

PubMed

Habibi, Mohammad Hossein; Mardani, Maryam

2015-02-25

Nano-composite containing zinc oxide-tin oxide was obtained by a facile co-precipitation route using tin chloride tetrahydrate and zinc chloride as precursors and coated on glass by Doctor Blade deposition. The crystalline structure and morphology of composites were evaluated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The XRD results showed peaks relative to zinc oxide with hexagonal wurtzite structure and tin oxide with tetragonal structure. FESEM observations showed that the nano-composite consisted of aggregates of particles with an average particle size of 18 nm. The photocatalytic activity of the pure SnO2, pure ZnO, ZnSnO3-Zn2SnO4 and ZnO-SnO2 nano-structure thin films was examined using the degradation of a textile dye Reactive Blue 160 (KE2B). ZnO-SnO2 nano-composite showed enhanced photo-catalytic activity than the pure zinc oxide and tin oxide. The enhanced photo-catalytic activity of the nano-composite was ascribed to an improved charge separation of the photo-generated electron-hole pairs. Copyright © 2014 Elsevier B.V. All rights reserved.

Modified corrosion protection coatings for Concrete tower of Transmission line

NASA Astrophysics Data System (ADS)

Guo, Kai; Jing, Xiangyang; Wang, Hongli; Yue, Zengwu; Wu, Yaping; Mi, Xuchun; Li, Xingeng; Chen, Suhong; Fan, Zhibin

2017-12-01

By adding nano SiO2 particles, an enhanced K-PRTV anti-pollution flashover coating had been prepared. Optical profile meter (GT-K), atomic force microscopy (AFM) and infrared spectrometer (FT-IR) characterization were carried out on the coating surface analysis. With the use of modified epoxy resin as the base material, the supplemented by phosphate as a corrosion stabilizer, to achieve a corrosion of steel and galvanized steel with rust coating. Paint with excellent adhesion, more than 10MPa (1), resistant to neutral salt spray 1000h does not appear rust point. At the same time coating a large amount of ultra-fine zinc powder can be added for the tower galvanized layer zinc repair function, while the paint in the zinc powder for the tower to provide sacrificial anode protection, to achieve self-repair function of the coating. Compared to the market with a significant reduction in the cost of rust paint, enhance the anti-corrosion properties.

Bactericidal activities of woven cotton and nonwoven polypropylene fabrics coated with hydroxyapatite-binding silver/titanium dioxide ceramic nanocomposite “Earth-plus”

PubMed Central

Kasuga, Eriko; Kawakami, Yoshiyuki; Matsumoto, Takehisa; Hidaka, Eiko; Oana, Kozue; Ogiwara, Naoko; Yamaki, Dai; Sakurada, Tsukasa; Honda, Takayuki

2011-01-01

Background Bacteria from the hospital environment, including linens and curtains, are often responsible for hospital-associated infections. The aim of the present study was to evaluate the bactericidal effects of fabrics coated with the hydroxyapatite-binding silver/titanium dioxide ceramic nanocomposite “Earth-plus”. Methods Bactericidal activities of woven and nonwoven fabrics coated with Earth-plus were investigated by the time-kill curve method using nine bacterial strains, including three Staphylococcus aureus, three Escherichia coli, and three Pseudomonas aeruginosa strains. Results The numbers of viable S. aureus and E. coli cells on both fabrics coated with Earth-plus decreased to below 2 log10 colony-forming units/mL in six hours and reached the detection limit in 18 hours. Viable cell counts of P. aeruginosa on both fabrics coated with Earth-plus could not be detected after 3–6 hours. Viable cells on woven fabrics showed a more rapid decline than those on nonwoven fabrics. Bacterial cell counts of the nine strains on fabrics without Earth-plus failed to decrease even after 18 hours. Conclusion Woven cotton and nonwoven polypropylene fabrics were shown to have excellent antibacterial potential. The woven fabric was more bactericidal than the nonwoven fabric. PMID:21931489

Optical limiting in gelatin stabilized Cu-PVP nanocomposite colloidal suspension

NASA Astrophysics Data System (ADS)

Tamgadge, Y. S.; Gedam, P. P.; Thakare, N. B.; Talwatkar, S. S.; Sunatkari, A. L.; Muley, G. G.

2018-05-01

This article illustrates investigations on optical limiting properties of Cu-PVP nanocomposite colloidal suspension. Gelatin stabilized Cu nanoparticles have been synthesized using chemical reduction method and thin films in PVP matrix have been obtained using spin coating technique. Thin films have been characterized by X-ray diffraction (XRD), Ultraviolet-visible (UV-vis) spectroscopy, etc. for structural and linear optical studies. Optical limiting properties of Colloidal Cu-PVP nanocomposites have been investigated at 808 nm diode CW laser. Minimum optical limiting threshold was found for GCu3-PVP nanocomposites sample. The strong optical limiting is thermal in origin as CW laser is used and effects are attributed to thermal lensing effect.

Method for providing uranium with a protective copper coating

DOEpatents

Waldrop, Forrest B.; Jones, Edward

1981-01-01

The present invention is directed to a method for providing uranium metal with a protective coating of copper. Uranium metal is subjected to a conventional cleaning operation wherein oxides and other surface contaminants are removed, followed by etching and pickling operations. The copper coating is provided by first electrodepositing a thin and relatively porous flash layer of copper on the uranium in a copper cyanide bath. The resulting copper-layered article is then heated in an air or inert atmosphere to volatilize and drive off the volatile material underlying the copper flash layer. After the heating step an adherent and essentially non-porous layer of copper is electro-deposited on the flash layer of copper to provide an adherent, multi-layer copper coating which is essentially impervious to corrosion by most gases.

BORED AND ASSEMBLED GATE VALVES RECEIVING PROTECTIVE COATING IN THE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

BORED AND ASSEMBLED GATE VALVES RECEIVING PROTECTIVE COATING IN THE VALVE PAINT BOOTH OF THE VALVE ASSEMBLY BUILDING. - Stockham Pipe & Fittings Company, Valve Assembly Building, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

Study of organic ablative thermal-protection coating for solid rocket motor

NASA Astrophysics Data System (ADS)

Hua, Zenggong

1992-06-01

A study is conducted to find a new interior thermal-protection material that possesses good thermal-protection performance and simple manufacturing possibilities. Quartz powder and Cr2O3 are investigated using epoxy resin as a binder and Al2O3 as the burning inhibitor. Results indicate that the developed thermal-protection coating is suitable as ablative insulation material for solid rocket motors.

Corrosion Protection Performance of Nano-SiO2/Epoxy Composite Coatings in Acidic Desulfurized Flue Gas Condensates

NASA Astrophysics Data System (ADS)

Wang, Z. B.; Wang, Z. Y.; Hu, H. X.; Liu, C. B.; Zheng, Y. G.

2016-09-01

Five kinds of nano-SiO2/epoxy composite coatings were prepared on mild steels, and their corrosion protection performance was evaluated at room temperature (RT) and 50 °C (HT) using electrochemical methods combined with scanning electron microscopy (SEM). The effects of preparation and sealing processes on the corrosion protection performance of epoxy coatings were specially focused on. The results showed that it was favorable for the corrosion protection and durable performance to add the modified nano-SiO2 during rather than after the synthesis of epoxy coatings. Furthermore, the employment of sealer varnish also had beneficial effects. The two better coatings still exhibited higher impedance values even after immersion tests for up to 1000 h at RT and 500 h at HT. SEM revealed that the improvement of corrosion protection performance mainly resulted from the enhancement of coating density. Moreover, the evolution of electrochemical behavior of the two better coatings with immersion time was also discussed by means of fitting the electrochemical impedance spectroscopy results using equivalent circuits with different physical meanings.

Enhancement of thermal conductive pathway of boron nitride coated polymethylsilsesquioxane composite.

PubMed

Kim, Gyungbok; Ryu, Seung Han; Lee, Jun-Tae; Seong, Ki-Hun; Lee, Jae Eun; Yoon, Phil-Joong; Kim, Bum-Sung; Hussain, Manwar; Choa, Yong-Ho

2013-11-01

We report here in the fabrication of enhanced thermal conductive pathway nanocomposites of boron nitride (BN)-coated polymethylsilsesquioxane (PMSQ) composite beads using isopropyl alcohol (IPA) as a mixing medium. Exfoliated and size-reduced boron nitride particles were successfully coated on the PMSQ beads and explained by surface charge differences. A homogeneous dispersion and coating of BN on the PMSQ beads using IPA medium was confirmed by SEM. Each condition of the composite powder was carried into the stainless still mould and then hot pressed in an electrically heated hot press machine. Three-dimensional percolation networks and conductive pathways created by exfoliated BN were precisely formed in the nanocomposites. The thermal conductivity of nanocomposites was measured by multiplying specific gravity, specific heat, and thermal diffusivity, based upon the laser flash method. Densification of the composite resulted in better thermal properties. For an epoxy reinforced composite with 30 vol% BN and PMSQ, a thermal conductivity of nine times higher than that of pristine PMSQ was observed.

Porous Se@SiO2 nanocomposites protect the femoral head from methylprednisolone-induced osteonecrosis.

PubMed

Deng, Guoying; Dai, Chenyun; Chen, Jinyuan; Ji, Anqi; Zhao, Jingpeng; Zhai, Yue; Kang, Yingjie; Liu, Xijian; Wang, Yin; Wang, Qiugen

2018-01-01

Methylprednisolone (MPS) is an important drug used in therapy of many diseases. However, osteonecrosis of the femoral head is a serious damage in the MPS treatment. Thus, it is imperative to develop new drugs to prevent the serious side effect of MPS. The potential interferences Se@SiO 2 nanocomposites may have to the therapeutic effect of methylprednisolone (MPS) were evaluated by classical therapeutic effect index of acute respiratory distress syndrome (ARDS), such as wet-to-dry weight ratio, inflammatory factors IL-1β and TNF-α. And oxidative stress species (ROS) index like superoxide dismutase (SOD) and glutathione (GSH) were tested. Then, the protection effects of Se@SiO 2 have in osteonecrosis of the femoral head (ONFH) were evaluated by micro CT, histologic analysis and Western-blot analysis. In the present study, we found that in the rat model of ARDS, Se@SiO 2 nanocomposites induced SOD and GSH indirectly to reduce ROS damage. The wet-to-dry weight ratio of lung was significantly decreased after MPS treatment compared with the control group, whereas the Se@SiO 2 did not affect the reduced wet-to-dry weight ratio of MPS. Se@SiO 2 also did not impair the effect of MPS on the reduction of inflammatory factors IL-1β and TNF-α, and on the alleviation of structural destruction. Furthermore, micro CT and histologic analysis confirmed that Se@SiO 2 significantly alleviate MPS-induced destruction of femoral head. Moreover, compared with MPS group, Se@SiO 2 could increase collagen II and aggrecan, and reduce the IL-1β level in the cartilage of femoral head. In addition, the biosafety of Se@SiO 2 in vitro and in vivo were supported by cell proliferation assay and histologic analysis of main organs from rat models. Se@SiO 2 nanocomposites have a protective effect in MPS-induced ONFH without influence on the therapeutic activity of MPS, suggesting the potential as effective drugs to avoid ONFH in MPS therapy.

Porous Se@SiO2 nanocomposites protect the femoral head from methylprednisolone-induced osteonecrosis

PubMed Central

Chen, Jinyuan; Ji, Anqi; Zhao, Jingpeng; Zhai, Yue; Kang, Yingjie; Liu, Xijian; Wang, Yin; Wang, Qiugen

2018-01-01

Background Methylprednisolone (MPS) is an important drug used in therapy of many diseases. However, osteonecrosis of the femoral head is a serious damage in the MPS treatment. Thus, it is imperative to develop new drugs to prevent the serious side effect of MPS. Methods The potential interferences Se@SiO2 nanocomposites may have to the therapeutic effect of methylprednisolone (MPS) were evaluated by classical therapeutic effect index of acute respiratory distress syndrome (ARDS), such as wet-to-dry weight ratio, inflammatory factors IL-1β and TNF-α. And oxidative stress species (ROS) index like superoxide dismutase (SOD) and glutathione (GSH) were tested. Then, the protection effects of Se@SiO2 have in osteonecrosis of the femoral head (ONFH) were evaluated by micro CT, histologic analysis and Western-blot analysis. Results In the present study, we found that in the rat model of ARDS, Se@SiO2 nanocomposites induced SOD and GSH indirectly to reduce ROS damage. The wet-to-dry weight ratio of lung was significantly decreased after MPS treatment compared with the control group, whereas the Se@SiO2 did not affect the reduced wet-to-dry weight ratio of MPS. Se@SiO2 also did not impair the effect of MPS on the reduction of inflammatory factors IL-1β and TNF-α, and on the alleviation of structural destruction. Furthermore, micro CT and histologic analysis confirmed that Se@SiO2 significantly alleviate MPS-induced destruction of femoral head. Moreover, compared with MPS group, Se@SiO2 could increase collagen II and aggrecan, and reduce the IL-1β level in the cartilage of femoral head. In addition, the biosafety of Se@SiO2 in vitro and in vivo were supported by cell proliferation assay and histologic analysis of main organs from rat models. Conclusion Se@SiO2 nanocomposites have a protective effect in MPS-induced ONFH without influence on the therapeutic activity of MPS, suggesting the potential as effective drugs to avoid ONFH in MPS therapy. PMID:29606872

Role of carbon nanotube dispersion in fracture toughening of plasma sprayed aluminum oxide-carbon nanotube nanocomposite coating

NASA Astrophysics Data System (ADS)

Balani, Kantesh

Aluminum oxide (Al2O3, or alumina) is a conventional ceramic known for applications such as wear resistant coatings, thermal liners, heaters, crucibles, dielectric systems, etc. However applications of Al 2O3 are limited owing to its inherent brittleness. Due to its excellent mechanical properties and bending strength, carbon nanotubes (CNT) is an ideal reinforcement for Al2O3 matrix to improve its fracture toughness. The role of CNT dispersion in the fracture toughening of the plasma sprayed Al2O3-CNT nanocomposite coating is discussed in the current work. Pretreatment of powder feedstock is required for dispersing CNTs in the matrix. Four coatings namely spray dried Al2O 3 (A-SD), Al2O3 blended with 4wt.% CNT (A4C-B), composite spray dried Al2O3-4wt.% CNT (A4C-SD) and composite spray dried A1203-8wt.% CNT (A8C-SD), are synthesized by plasma spraying. Owing to extreme temperatures and velocities involved in the plasma spraying of ceramics, retention of CNTs in the resulting coatings necessitates optimizing plasma processing parameters using an inflight particle diagnostic sensor. A bimodal microstructure was obtained in the matrix that consists of fully melted and resolidified structure and solid state sintered structure. CNTs are retained both in the fully melted region and solid-state sintered regions of processed coatings. Fracture toughness of A-SD, A4C-B, A4C-SD and A8C-SD coatings was 3.22, 3.86, 4.60 and 5.04 MPa m1/2 respectively. This affirms the improvement of fracture toughness from 20% (in A4C-B coating) to 43% (in A4C-SD coating) when compared to the A-SD coating because of the CNT dispersion. Fracture toughness improvement from 43% (in A4C-SD) to 57% (in A8C-SD) coating is evinced because of the CNT content. Reinforcement by CNTs is described by its bridging, anchoring, hook formation, impact alignment, fusion with splat, and mesh formation. The Al2O3/CNT interface is critical in assisting the stress transfer and utilizing excellent mechanical

A high performance nonenzymatic electrochemical glucose sensor based on polyvinylpyrrolidone-graphene nanosheets-nickel nanoparticles-chitosan nanocomposite.

PubMed

Liu, Zhiguang; Guo, Yujing; Dong, Chuan

2015-05-01

In this report, a new nanocomposite was successfully synthesized by chemical deposition of nickel nanoparticles (NiNPs) on polyvinylpyrrolidone (PVP) stabilized graphene nanosheets (GNs) with chitosan (CS) as the protective coating. The as obtained nanocomposite (PVP-GNs-NiNPs-CS) was characterized by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Benefiting from the synergistic effect of GNs (large surface area and high conductivity), NiNPs (high electrocatalytic activity towards the glucose oxidation) and CS (good film-forming and antifouling ability), a nonenzymatic electrochemical glucose sensor was established. The nanocomposite displays greatly enhanced electrocatalytic activity towards the glucose oxidation in NaOH solution. The PVP-GNs-NiNPs-CS based electrochemical glucose sensor demonstrates good sensitivity, wide linear range (0.1 μM-0.5 mM), outstanding detection limit (30 nM), attractive selectivity, good reproducibility, high stability as well as prominent feasibility for the real sample analysis. The proposed experiment might open up a new possibility for widespread use of non-enzymatic sensors for monitoring blood glucose owing to its advantages of low cost, simple preparation and excellent properties for glucose detection. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of protective coating on microhardness of a new glass ionomer cement: Nanofilled coating versus unfilled resin

PubMed Central

Faraji, Foad; Heshmat, Haleh; Banava, Sepideh

2017-01-01

Background and Objectives: EQUIATM is a new gastrointestinal (GI) system with high compressive strength, surface microhardness (MH), and fluoride release potential. This in vitro study aimed to assess the effect of aging and type of protective coating on the MH of EQUIATM GI cement. Materials and Methods: A total of 30 disc-shaped specimens measuring 9 mm in diameter and 2 mm in thickness were fabricated of EQUIATM GI and divided into three groups of G-Coat nanofilled coating (a), no coating (b) and margin bond (c). The Vickers MH value of specimens was measured before (baseline) and at 3 and 6 months after water storage. Data were analyzed using repeated measures ANOVA. Results: Group B had significantly higher MH than the other two groups at baseline. Both G-Coat and margin bond increased the surface MH of GI at 3 and 6 months. The MH values of G-Coat and margin bond groups did not significantly increase or decrease between 3 and 6 months. Conclusion: The increase in MH was greater in the G-Coat compared to the margin bond group in the long-term. Clinically, margin bond may be a suitable alternative when G-Coat is not available. PMID:29259364

Water Diffusion through a Titanium Dioxide/Poly(Carbonate Urethane) Nanocomposite for Protecting Cultural Heritage: Interactions and Viscoelastic Behavior

PubMed Central

Abbate, Mario; D’Orazio, Loredana

2017-01-01

Water diffusion through a TiO2/poly (carbonate urethane) nanocomposite designed for the eco-sustainable protection of outdoor cultural heritage stonework was investigated. Water is recognized as a threat to heritage, hence the aim was to gather information on the amount of water uptake, as well as of species of water molecules absorbed within the polymer matrix. Gravimetric and vibrational spectroscopy measurements demonstrated that diffusion behavior of the nanocomposite/water system is Fickian, i.e., diffusivity is independent of concentration. The addition of only 1% of TiO2 nanoparticles strongly betters PU barrier properties and water-repellency requirement is imparted. Defensive action against penetration of water free from, and bonded through, H-bonding association arises from balance among TiO2 hydrophilicity, tortuosity effects and quality of nanoparticle dispersion and interfacial interactions. Further beneficial to antisoiling/antigraffiti action is that water-free fraction was found to be desorbed at a constant rate. In environmental conditions, under which weathering processes are most likely to occur, nanocomposite Tg values remain suitable for heritage treatments. PMID:28902179

The corrosion protection of 6061-T6 aluminum by a polyurethane-sealed anodized coat

NASA Technical Reports Server (NTRS)

Danford, M. D.

1990-01-01

The corrosion protection of 6061-T6 anodized aluminum afforded by a newly patented polyurethane seal was studied using the ac impedance technique. Values of the average corrosion rates over a 27-day exposure period in 3.5 percent NaCl solutions at pH 5.2 and pH 9.5 compared very favorably for Lockheed-prepared polyurethane-sealed and dichromate-sealed coats of the same thickness. Average corrosion rates for both specimens over the first 7 days of exposure compared well with those for a hard anodized, dichromate-sealed coat, but rose well above those for the hard anodized coat over the entire 27-day period. This is attributed both to the greater thickness of the hard anodized coat, and possibly to its inherently better corrosion protective capability.

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

indicators, inhibitors and self-healing agents. This allows the incorporation of autonomous corrosion control functionalities, such as corrosion detection and inhibition as well as the self-healing of mechanical damage, into coatings. This paper presents technical details on the characterization of inhibitor-containing particles and their corrosion inhibitive effects using electrochemical and mass loss methods.Three organic environmentally friendly corrosion inhibitors were encapsulated in organic microparticles that are compatible with desired coatings. The release of the inhibitors from the microparticles in basic solution was studied. Fast release, for immediate corrosion protection, as well as long-term release for continued protection, was observed.The inhibition efficacy of the inhibitors, incorporated directly and in microparticles, on carbon steel was evaluated. Polarization curves and mass loss measurements showed that, in the case of 2MBT, its corrosion inhibition effectiveness was greater when it was delivered from microparticles.

Coatings for Oxidation and Hot Corrosion Protection of Disk Alloys

NASA Technical Reports Server (NTRS)

Nesbitt, Jim; Gabb, Tim; Draper, Sue; Miller, Bob; Locci, Ivan; Sudbrack, Chantal

2017-01-01

Increasing temperatures in aero gas turbines is resulting in oxidation and hot corrosion attack of turbine disks. Since disks are sensitive to low cycle fatigue (LCF), any environmental attack, and especially hot corrosion pitting, can potentially seriously degrade the life of the disk. Application of metallic coatings are one means of protecting disk alloys from this environmental attack. However, simply the presence of a metallic coating, even without environmental exposure, can degrade the LCF life of a disk alloy. Therefore, coatings must be designed which are not only resistant to oxidation and corrosion attack, but must not significantly degrade the LCF life of the alloy. Three different Ni-Cr coating compositions (29, 35.5, 45wt. Cr) were applied at two thicknesses by Plasma Enhanced Magnetron Sputtering (PEMS) to two similar Ni-based disk alloys. One coating also received a thin ZrO2 overcoat. The coated samples were also given a short oxidation exposure in a low PO2 environment to encourage chromia scale formation. Without further environmental exposure, the LCF life of the coated samples, evaluated at 760C, was less than that of uncoated samples. Hence, application of the coating alone degraded the LCF life of the disk alloy. Since shot peening is commonly employed to improve LCF life, the effect of shot peening the coated and uncoated surface was also evaluated. For all cases, shot peening improved the LCF life of the coated samples. Coated and uncoated samples were shot peened and given environmental exposures consisting of 500 hrs of oxidation followed by 50 hrs of hot corrosion, both at 760C). The high-Cr coating showed the best LCF life after the environmental exposures. Results of the LCF testing and post-test characterization of the various coatings will be presented and future research directions discussed.

Microcapsule-Type Self-Healing Protective Coating for Cementitious Composites with Secondary Crack Preventing Ability.

PubMed

Kim, Dong-Min; Yu, Hwan-Chul; Yang, Hye-In; Cho, Yu-Jin; Lee, Kwang-Myong; Chung, Chan-Moon

2017-01-26

A microcapsule-type self-healing protective coating with secondary crack preventing capability has been developed using a silanol-terminated polydimethylsiloxane (STP)/dibutyltin dilaurate (DD) healing agent. STP undergoes condensation reaction in the presence of DD to give a viscoelastic substance. STP- and DD-containing microcapsules were prepared by in-situ polymerization and interfacial polymerization methods, respectively. The microcapsules were characterized by Fourier-transform infrared (FT-IR) spectroscopy, optical microscopy, and scanning electron microscopy (SEM). The microcapsules were integrated into commercial enamel paint or epoxy coating formulations, which were applied on silicon wafers, steel panels, and mortar specimens to make dual-capsule self-healing protective coatings. When the STP/DD-based coating was scratched, self-healing of the damaged region occurred, which was demonstrated by SEM, electrochemical test, and water permeability test. It was also confirmed that secondary crack did not occur in the healed region upon application of vigorous vibration to the self-healing coating.

Microcapsule-Type Self-Healing Protective Coating for Cementitious Composites with Secondary Crack Preventing Ability

PubMed Central

Kim, Dong-Min; Yu, Hwan-Chul; Yang, Hye-In; Cho, Yu-Jin; Lee, Kwang-Myong; Chung, Chan-Moon

2017-01-01

A microcapsule-type self-healing protective coating with secondary crack preventing capability has been developed using a silanol-terminated polydimethylsiloxane (STP)/dibutyltin dilaurate (DD) healing agent. STP undergoes condensation reaction in the presence of DD to give a viscoelastic substance. STP- and DD-containing microcapsules were prepared by in-situ polymerization and interfacial polymerization methods, respectively. The microcapsules were characterized by Fourier-transform infrared (FT-IR) spectroscopy, optical microscopy, and scanning electron microscopy (SEM). The microcapsules were integrated into commercial enamel paint or epoxy coating formulations, which were applied on silicon wafers, steel panels, and mortar specimens to make dual-capsule self-healing protective coatings. When the STP/DD-based coating was scratched, self-healing of the damaged region occurred, which was demonstrated by SEM, electrochemical test, and water permeability test. It was also confirmed that secondary crack did not occur in the healed region upon application of vigorous vibration to the self-healing coating. PMID:28772475

Shop primer as part of the corrosion protective coating for submerged steel structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bjordal, M.; Steinsmo, U.

In Norwegian workshops the standard pre-treatment procedures for steel structures intended for sub-sea use, normally include removal of shop primer by blast cleaning to Sa 2 1/2 before application of corrosion protective coatings. This is also stated in the Norwegian offshore standard NORSOK. Omitting this stage in fabrication will represent large reductions in both time consumption and costs, and reduce the volume of waste from the blast cleaning. This report presents results from investigations of how a shop primer will influence on the coating properties. The aim of the investigation was to test whether the systems are good enough ifmore » the shop primer is left on the surface. Two different zinc silicate shop primers have been included in the investigation. As protective coatings the authors have used three different epoxy mastic systems with Al pigments. In addition to panels with original shop primer, they have also tested shop primed panels pre-treated in various ways, such as heated, corroded and blast cleaned to various degrees before coating. The coatings have been tested in the ASTM-G8 121 test and in a long term test in sea water polarized with a Zn anode. They have found that coatings including the zinc silicate shop primer are more susceptible to cathodic disbonding than the coating applied directly on blast cleaned steel. It is however possible to meet the NORSOK criteria with a zinc silicate shop primer as first coat.« less

Dielectric property study of poly(4-vinylphenol)-graphene oxide nanocomposite thin film

NASA Astrophysics Data System (ADS)

Roy, Dhrubojyoti

2018-05-01

Thin film capacitor device having a sandwich structure of indium tin oxide (ITO)-coated glass/polymer or polymer nanocomposite /silver has been fabricated and their dielectric and leakage current properties has been studied. The dielectric properties of the capacitors were characterized for frequencies ranging from 1 KHz to 1 MHz. 5 wt% Poly(4-vinylphenol)(PVPh)-Graphene (GO) nanocomposite exhibited an increase in dielectric constant to 5.6 and small rise in dielectric loss to around˜0.05 at 10 KHz w.r.t polymer. The DC conductivity measurements reveal rise of leakage current in nanocomposite.

High Temperature Resistant Organopolysiloxane Coating for Protecting and Repairing Rigid Thermal Insulation

NASA Technical Reports Server (NTRS)

Leiser, Daniel B. (Inventor); Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

1999-01-01

Ceramics are protected from high temperature degradation, including high temperature, oxidative, aeroconvective degradation by a high temperature and oxidation resistant coating of a room temperature curing, hydrolyzed and partially condensed liquid polyorganosiloxane to the surface of the ceramic. The liquid polyorganosiloxane is formed by the hydrolysis and partial condensation of an alkyltrialkoxysilane with water or a mixture of an alkyltrialkoxysilane and a dialkyldialkoxysilane with water. The liquid polyorganosiloxane cures at room temperature on the surface of the ceramic to form a hard, protective, solid coating which forms a high temperature environment, and is also used as an adhesive for adhering a repair plug in major damage to the ceramic. This has been found useful for protecting and repairing porous, rigid ceramics of a type used on reentry space vehicles.

Corrosion Resistance Characterization of Coating Systems Used to Protect Aluminum Alloys Using Electrochemical Impedance Spectroscopy and Artificial Neural Networks

NASA Astrophysics Data System (ADS)

Gambina, Federico

In this study, the corrosion protection provided by of a number of chromate and chromate-free coatings systems was characterized in detail. High-solids SrCrO4-pigmented epoxy primers applied to 2024 and 7075 substrates were subject to salt spray exposure testing for 30 days. Samples were removed periodically and an electrochemical impedance measurement (EIS) was made. Although none of the coatings tested showed visual evidence of corrosion, the total impedance of the samples decreased by as much as two orders of magnitude. An analysis of capacitance showed that the primer coatings rapidly took up water from the exposure environment, but the coating-metal remained passive despite the fact that it was wet. These results support the idea that chromate coatings protect by creating a chromate-rich electrolyte within the coating that is passivating to the underlying metal substrate. They also suggest that indications of metal substrate passivity found in the low-frequency capacitive reactance of the impedance spectra are a better indicator of corrosion protection than the total impedance. The low-frequency capacitive reactance from EIS measurements is also good at assessing the protectiveness of chromate-free coatings systems. Fifteen different coatings systems comprising high-solids, chromate-free primers and chromate-free conversion coatings were applied to 2024 and 7075 substrates. These coatings were subject to salt spray exposure and EIS measurements. All coatings were inferior to coating systems containing chromate, but changes in the capacitive reactance measured in EIS was shown to anticipate visual indications of coating failure. A predictive model based on neural networks was trained to recognize the pattern in the capacitive reactance in impedance spectra measured after 48 hours of exposure and make an estimate of remaining coating life. A sensitivity analysis was performed to prune the impedance inputs. As a result of this analysis, a very simple but highly

Strain Compatible Oxidation and Corrosion Protection Coatings for Enhanced Thermo-Mechanical Durability of Turbine Airfoils

DTIC Science & Technology

2011-12-05

Report: Grant N00014-08-0331 Technical Objectives As critical components of advanced aircraft engines , turbine airfoils require coatings for...advanced aircrafi engines , turbine airfoils require coatings for enhancement of oxidation, corrosion and thermal capabilities . Airfoil coatings ofien...Oxidation and Corrosion Protection Coatings for Enhanced Thermo-Mechanical Durability of Turbine Airfoils 5b. GRANT NUMBER N00014-08-l-0331 5c

Wear Resistance Properties Reinforcement Using Nano-Al/Cu Composite Coating in Sliding Bearing Maintenance.

PubMed

Liu, Hongtao; Li, Zhixiong; Wang, Jianmei; Sheng, Chenxing; Liu, Wanli

2018-03-01

Sliding bearing maintenance is crucial for reducing the cost and extending the service life. An efficient and practical solution is to coat a restorative agent onto the worn/damaged bearings. Traditional pure-copper (Cu) coating results in a soft surface and poor abrasion resistance. To address this issue, this paper presents a nano-composite repairing coating method. A series of nano-Al/Cu coatings were prepared on the surface of 45 steel by composite electro-brush plating (EBP). Their micro-hardness was examined by a MHV-2000 Vickers hardness tester, and tribological properties by a UMT-2M Micro-friction tester, 3D profiler and SEM. Then, the influence of processing parameters such as nano-particle concentration and coating thickness on the micro-hardness of nano-Al/Cu coating was analyzed. The experimental analysis results demonstrate that, when the nano-Al particle concentration in electrolyte was 10 g/L, the micro-hardness of the composite coating was 1.1 times as much as that of pure-Cu coating. When the Al nano-particle concentration in electrolyte was 20 g/L, the micro-hardness of the composite coating reached its maximum value (i.e., 231.6 HV). Compared with the pure-Cu coating, the hardness and wear resistance of the nano-composite coating were increased, and the friction coefficient and wear volume were decreased, because of the grain strengthening and dispersion strengthening. The development in this work may provide a feasible and effective nano-composite EBP method for sliding bearing repair.

A facile fabrication of multifunctional knit polyester fabric based on chitosan and polyaniline polymer nanocomposite

NASA Astrophysics Data System (ADS)

Tang, Xiaoning; Tian, Mingwei; Qu, Lijun; Zhu, Shifeng; Guo, Xiaoqing; Han, Guangting; Sun, Kaikai; Hu, Xili; Wang, Yujiao; Xu, Xiaoqi

2014-10-01

Knit polyester fabric was successively modified and decorated with chitosan layer and polyaniline polymer nanocomposite layer in this paper. The fabric was firstly treated with chitosan to form a stable layer through the pad-dry-cure process, and then the polyaniline polymer nanocomposite layer was established on the outer layer by in situ chemical polymerization method using ammonium persulfate as oxidant and chlorhydric acid as dopant. The surface morphology of coated fabric was characterized by scanning electron microscopy (SEM), and the co-existence of chitosan layer and granular polyaniline polymer nanocomposite was confirmed and well dispersed on the fabric surface. The resultant fabric was endowed with remarkable electrical conductivity properties and efficient water-repellent capability, which also have been found stable after water laundering. In addition, the photocatalytic decomposition activity for reactive red dye was observed when the multifunctional knit polyester fabric was exposed to the illumination of ultraviolet lamp. These results indicated that chitosan and polyaniline polymer nanocomposite could form ideal multifunctional coatings on the surface of knit polyester fabric.

Reactive Nanocomposites for Controllable Adhesive Debonding

DTIC Science & Technology

2011-08-01

technologies include shape memory alloy (SMA)-based approach, a chemical foaming agent (CFA) approach, and a reactive nanocomposite (RNC) approach. SMA...anofoil (a) Component 1 Thermoset Adhesive Component 2 Nano-coating (b) Figure 2. Debonding approach where (a) freestanding...J. Controlled Adhesive Debonding of RAH-66 Comanche Chines Using Shape Memory Alloys ; ARL-TR-2937; U.S. Army Research Laboratory: Aberdeen Proving

Solid-phase microextraction of methadone in urine samples by electrochemically co-deposited sol-gel/Cu nanocomposite fiber.

PubMed

Mohammadiazar, Sirwan; Hasanli, Fateme; Maham, Mehdi; Payami Samarin, Somayeh

2017-08-01

Electrochemically co-deposited sol-gel/Cu nanocomposites have been introduced as a novel, simple and single-step technique for preparation of solid-phase microextraction (SPME) coating to extract methadone (MDN) (a synthetic opioid) in urine samples. The porous surface structure of the sol-gel/Cu nanocomposite coating was revealed by scanning electron microscopy. Direct immersion SPME followed by HPLC-UV determination was employed. The factors influencing the SPME procedure, such as the salt content, desorption solvent type, pH and equilibration time, were optimized. The best conditions were obtained with no salt content, acetonitrile as desorption solvent type, pH 9 and 10 min equilibration time. The calibration graphs for urine samples showed good linearity. The detection limit was about 0.2 ng mL -1 . Also, the novel method for preparation of nanocomposite fiber was compared with previously reported techniques for MDN determination. The results show that the novel nanocomposite fiber has relatively high extraction efficiency. Copyright © 2016 John Wiley & Sons, Ltd.

Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings

PubMed Central

Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

2016-01-01

Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings. PMID:26924136

Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings.

PubMed

Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

2016-02-29

Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings.

Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings

NASA Astrophysics Data System (ADS)

Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

2016-02-01

Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings.

Self-assembled nanolaminate coatings (SV)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, H.

2012-03-01

Sandia National Laboratories (Sandia) and Lockheed Martin Aeronautics (LM Aero) are collaborating to develop affordable, self-assembled, nanocomposite coatings and associated fabrication processes that will be tailored to Lockheed Martin product requirements. The purpose of this project is to develop a family of self-assembled coatings with properties tailored to specific performance requirements, such as antireflective (AR) optics, using Sandia-developed self-assembled techniques. The project met its objectives by development of a simple and economic self-assembly processes to fabricate multifunctional coatings. Specifically, materials, functionalization methods, and associated coating processes for single layer and multiple layers coatings have been developed to accomplish high reflectivemore » coatings, hydrophobic coatings, and anti-reflective coatings. Associated modeling and simulations have been developed to guide the coating designs for optimum optical performance. The accomplishments result in significant advantages of reduced costs, increased manufacturing freedom/producibility, improved logistics, and the incorporation of new technology solutions not possible with conventional technologies. These self-assembled coatings with tailored properties will significantly address LMC's needs and give LMC a significant competitive lead in new engineered materials. This work complements SNL's LDRD and BES programs aimed at developing multifunctional nanomaterials for microelectronics and optics as well as structure/property investigations of self-assembled nanomaterials. In addition, this project will provide SNL with new opportunities to develop and apply self-assembled nanocomposite optical coatings for use in the wavelength ranges of 3-5 and 8-12 micrometers, ranges of vital importance to military-based sensors and weapons. The SANC technologies will be applied to multiple programs within the LM Company including the F-35, F-22, ADP (Future Strike Bomber, UAV

Surface coating of ceria nanostructures for high-temperature oxidation protection

NASA Astrophysics Data System (ADS)

Aadhavan, R.; Bhanuchandar, S.; Babu, K. Suresh

2018-04-01

Stainless steels are used in high-temperature structural applications but suffer from degradation at an elevated temperature of operation due to thermal stress which leads to spallation. Ceria coating over chromium containing alloys induces protective chromia layer formation at alloy/ceria interface thereby preventing oxidative degradation. In the present work, three metals of differing elemental composition, namely, AISI 304, AISI 410, and Inconel 600 were tested for high-temperature stability in the presence and absence of ceria coating. Nanoceria was used as the target to deposit the coating through electron beam physical vapor deposition method. After isothermal oxidation at 1243 K for 24 h, Ceria coated AISI 304 and Inconel 600 exhibited a reduced rate of oxidation by 4 and 1 orders, respectively, in comparison with the base alloy. The formation of spinel structure was found to be lowered in the presence of ceria due to the reduced migration of cations from the alloy.

Sunlight-induced self-healing of a microcapsule-type protective coating.

PubMed

Song, Young-Kyu; Jo, Ye-Hyun; Lim, Ye-Ji; Cho, Sung-Youl; Yu, Hwan-Chul; Ryu, Byung-Cheol; Lee, Sang-In; Chung, Chan-Moon

2013-02-01

Photopolymerization behavior of a methacryloxypropyl-terminated polydimethylsiloxane (MAT-PDMS) healing agent was investigated in the presence of benzoin isobutyl ether (BIE) photoinitiator by Fourier transform infrared (FT-IR) spectroscopy. MAT-PDMS and BIE were microencapsulated with urea-formaldehyde polymer. The surface and shell morphology of the microcapsules was investigated by scanning electron microscopy (SEM). Mean diameter and size distribution of the microcapsules could be controlled by agitation rate. A coating matrix formulation was prepared by sol-gel reaction of tetraethyl orthosilicate (TEOS) in the presence of a polysiloxane and by subsequent addition of an adhesion promoter. The formulation and microcapsules were mixed to give a self-healing coating formulation, which was then sprayed to surface of cellulose-fiber-reinforced-cement (CRC) board or mortar. Contact angle measurements showed that both the polymerized MAT-PDMS and the prepared coating matrix are hydrophobic, and the coating matrix has good wettability with MAT-PDMS. It was confirmed by optical microscopy and SEM that, when the self-healing coating is damaged, the healing agent is released from ruptured microcapsules and fills the damaged region. The self-healing coating was evaluated as protective coating for mortar, and it was demonstrated by water permeability and chloride ion penetration tests that our system has sunlight-induced self-healing capability. Our self-healing coating is the first example of capsule-type photoinduced self-healing system, and offers the advantages of catalyst-free, environmentally friendly, inexpensive, practical healing.

Galvanic Liquid Applied Coating Development for Protection of Steel in Concrete

NASA Technical Reports Server (NTRS)

Curran, Joseph John; Curran, Jerry; MacDowell, Louis

2004-01-01

Corrosion of reinforcing steel in concrete is a major problem affecting NASA facilities at Kennedy Space Center (KSC), other government agencies, and the general public. Problems include damage to KSC launch support structures, transportation and marine infrastructures, as well as building structures. A galvanic liquid applied coating was developed at KSC in order to address this problem. The coating is a non-epoxy metal rich ethyl silicate liquid coating. The coating is applied as a liquid from initial stage to final stage. Preliminary data shows that this coating system exceeds the NACE 100 millivolt shift criterion. The remainder of the paper details the development of the coating system through the following phases: Phase I: Development of multiple formulations of the coating to achieve easy application characteristics, predictable galvanic activity, long-term protection, and minimum environmental impact. Phase II: Improvement of the formulations tested in Phase I including optimization of metallic loading as well as incorporation of humectants for continuous activation. Phase III: Application and testing of improved formulations on the test blocks. Phase IV: Incorporation of the final formulation upgrades onto large instrumented structures (slabs).

Laser fabrication of Ag-HA nanocomposites on Ti6Al4V implant for enhancing bioactivity and antibacterial capability.

PubMed

Liu, Xiangmei; Man, H C

2017-01-01

For titanium alloy implants, both surface bioactivity and antibacterial infection are the two critical factors in determining the success of clinical implantation of these metallic implants. In the present work, a novel nanocomposite layer of nano-silver-containing hydroxyapatite (Ag-HA) was prepared on the surface of biomedical Ti6Al4V by laser processing. Analysis using SEM, EDS and XRD shows the formation of an Ag-HA layer of about 200μm fusion bonded to the substrate. Mineralization tests in simulated body fluid (SBF) showed that laser fabricated Ag-HA nanocomposite layer favors the deposition of apatite on the surface of the implants. Antibacterial tests confirmed that all Ag-HA nanocomposite layers can kill bacteria while a higher Ag content would lower the cytocompatibility of these coatings. Cell viability decreases when the Ag content reaches 5% in these coatings, due to the larger amount of Ag leached out, as confirmed by ion release evaluation. Our results reveal that laser fabricated Ag-HA nanocomposite coatings containing 2% Ag show both excellent cytocompatibility and antibacterial capability. Copyright © 2016 Elsevier B.V. All rights reserved.

Nanocomposites of natural rubber and polyaniline-modified cellulose nanofibrils

USDA-ARS?s Scientific Manuscript database

Cellulose nanofibrils (CNF) were isolated from cotton microfibrils (CM) by acid hydrolysis and coated with polyaniline (PANI) by in situ polymerization of aniline onto CNF in the presence of hydrochloride acid and ammonium peroxydisulfate to produce CNF/PANI. Nanocomposites of natural rubber (NR) re...

Vacuum ultraviolet coatings of Al protected with MgF(2) prepared both by ion-beam sputtering and by evaporation.

PubMed

Fernández-Perea, Mónica; Larruquert, Juan I; Aznárez, José A; Pons, Alicia; Méndez, José A

2007-08-01

Ion-beam sputtering (IBS) and evaporation are the two deposition techniques that have been used to deposit coatings of Al protected with MgF(2) with high reflectance in the vacuum ultraviolet down to 115 nm. Evaporation deposited (ED) Al protected with IBS MgF(2) resulted in a larger (smaller) reflectance below (above) 125 nm than the well-known all-evaporated coatings. A similar comparison is obtained when the Al film is deposited by IBS instead of evaporation. The lower reflectance of the coatings protected with IBS versus ED MgF(2) above 125 nm is because of larger absorption of the former. Both nonprotected IBS Al, as well as IBS Al protected with ED MgF(2), resulted in a band of reflectance loss that was peaked at 127 and 157 nm, respectively. This result was attributed to the excitation of surface plasmons due to the enhancement of surface roughness with large spatial wave vectors in the sputter deposition. This reflectance loss for IBS Al protected with MgF(2) is small at the short (lambda~120 nm) and long (lambda<350 nm) wavelengths investigated. IBS Al protected with ED MgF(2) is thus a promising coating for these two spectral regions. Coatings protected with IBS MgF(2) resulted in a reflectance as high as coatings protected with ED MgF(2) at wavelengths longer than 550 nm, whereas the former had a lower reflectance below this wavelength.

Multifunctional polymer nano-composite based superhydrophobic surface

NASA Astrophysics Data System (ADS)

Maitra, Tanmoy; Asthana, Ashish; Buchel, Robert; Tiwari, Manish K.; Poulikakos, Dimos

2014-11-01

Superhydrophobic surfaces become desirable in plethora of applications in engineering fields, automobile industry, construction industries to name a few. Typical fabrication of superhydrophobic surface consists of two steps: first is to create rough morphology on the substrate of interest, followed by coating of low energy molecules. However, typical exception of the above fabrication technique would be direct coating of functional polymer nanocomposites on substrate where superhydrophobicity is needed. Also in this case, the use of different nanoparticles in the polymer matrix can be exploited to impart multi-functional properties to the superhydrophobic coatings. Herein, different carbon nanoparticles like graphene nanoplatelets (GNP), carbon nanotubes (CNT) and carbon black (CB) are used in fluropolymer matrix to prepare superhydrophobic coatings. The multi-functional properties of coatings are enhanced by combining two different carbon fillers in the matrix. The aforementioned superhydrophobic coatings have shown high electrical conductivity and excellent droplet meniscus impalement resistance. Simultaneous superhydrophobic and oleophillic character of the above coating is used to separate mineral oil and water through filtration of their mixture. Swiss National Science Foundation (SNF) Grant 200021_135479.

Preparation and Characterization of WS2@SiO2 and WS2@PANI Core-Shell Nanocomposites

PubMed Central

Sade, Hagit

2018-01-01

Two tungsten disulfide (WS2)-based core-shell nanocomposites were fabricated using readily available reagents and simple procedures. The surface was pre-treated with a surfactant couple in a layer-by-layer approach, enabling good dispersion of the WS2 nanostructures in aqueous media and providing a template for the polymerization of a silica (SiO2) shell. After a Stöber-like reaction, a conformal silica coating was achieved. Inspired by the resulting nanocomposite, a second one was prepared by reacting the surfactant-modified WS2 nanostructures with aniline and an oxidizing agent in an aqueous medium. Here too, a conformal coating of polyaniline (PANI) was obtained, giving a WS2@PANI nanocomposite. Both nanocomposites were analyzed by electron microscopy, energy dispersive X-ray spectroscopy (EDS) and FTIR, verifying the core-shell structure and the character of shells. The silica shell was amorphous and mesoporous and the surface area of the composite increases with shell thickness. Polyaniline shells slightly differ in their morphologies dependent on the acid used in the polymerization process and are amorphous like the silica shell. Electron paramagnetic resonance (EPR) spectroscopy of the WS2@PANI nanocomposite showed variation between bulk PANI and the PANI shell. These two nanocomposites have great potential to expand the use of transition metals dichalcogenides (TMDCs) for new applications in different fields. PMID:29534426

An alternate to chromate conversion coatings for the corrosion protection of aluminum 2024-T3

NASA Astrophysics Data System (ADS)

Guo, Ruiguang

Corrosion of high-strength aluminum alloys used for airspace application is an expensive and serious problem. The most significant environmental factor contributing to the corrosion of these alloys is water condensed from humid air and contaminated with soluble chloride salts. The Al 2024 series used for aircraft are particularly susceptible to corrosion in aqueous chloride solutions due to alloying constituents such as copper and other impurities. Chromates are efficient inhibitors of corrosion of aluminum in near neutral aqueous environments containing aggressive anions such as chlorides. Usually, aluminum alloys are initially protected by chromate conversion coatings. Additional polymer coatings are sometimes added during exposure to corrosive atmospheres such as marine environments. Although chromate coatings are widely used, they require the use of noxious solutions, so they have always presented effluent disposal problems. There are health and safety concerns over the use of chromates due to their toxicity and carcinogenic nature and, as a consequence, the environmental and health risks associated with the use of such coatings will be restricted in the future. It was these health and safety concerns that led to the development of alternative non-toxic coating processes with comparable adhesion properties and corrosion protection. A variety of process technologies are under development and are vying for acceptance in industrial markets. As an alternate conversion coating, a new titanate conversion coating was systematically researched and developed. Research concentrated on producing passive surfaces from a simple titanate solution using an immersion process. The corrosion resistance of the treated surface has been evaluated using simple, rapid electrochemical techniques as well as a more long-term salt spray test. Passivation by titanate conversion treatment exhibits many similarities to chromate conversion treatment. Based on this study of corrosion

Self-healing coatings based on halloysite clay polymer composites for protection of copper alloys.

PubMed

Abdullayev, Elshad; Abbasov, Vagif; Tursunbayeva, Asel; Portnov, Vasiliy; Ibrahimov, Hikmat; Mukhtarova, Gulbaniz; Lvov, Yuri

2013-05-22

Halloysite clay nanotubes loaded with corrosion inhibitors benzotriazole (BTA), 2-mercaptobenzimidazole (MBI), and 2-mercaptobenzothiazole (MBT) were used as additives in self-healing composite paint coating of copper. These inhibitors form protective films on the metal surface and mitigate corrosion. Mechanisms involved in the film formation have been studied with optical and electron microscopy, UV-vis spectrometry, and adhesivity tests. Efficiency of the halloysite lumen loading ascended in the order of BTA < MBT < MBI; consequently, MBI and MBT halloysite formulations have shown the best protection. Inhibitors were kept in the tubes buried in polymeric paint layer for a long time and release was enhanced in the coating defects exposed to humid media with 20-50 h, sufficient for formation of protective layer. Anticorrosive performance of the halloysite-based composite acrylic and polyurethane coatings have been demonstrated for 110-copper alloy strips exposed to 0.5 M aqueous NaCl for 6 months.

Ground radiation tests and flight atomic oxygen tests of ITO protective coatings for Galileo Spacecraft

NASA Technical Reports Server (NTRS)

Bouquet, Frank L.; Maag, Carl R.

1986-01-01

Radiation simulation tests (protons and electrons) were performed along with atomic oxygen flight tests aboard the Shuttle to space qualify the surface protective coatings. The results, which contributed to the selection of indium-tin-oxide (ITO) coated polyester as the material for the thermal blankets of the Galileo Spacecraft, are given here. Two candidate materials, polyester and Fluorglas, were radiation-tested to determine changes at simulated Jovian radiation levels. The polyester exhibited a smaller weight loss (2.8) than the Fluorglas (8.8 percent). Other changes of polyester are given. During low-earth orbit, prior to transit to Jupiter, the thermal blankets would be exposed to atomic oxygen. Samples of uncoated and ITO-coated polyesters were flown on the Shuttle. Qualitative results are given which indicated that the ITO coating protected the underlying polyester.

Space Plasma Testing of High-Voltage Thin-Film Solar Arrays with Protective Coatings

NASA Technical Reports Server (NTRS)

Tlomak, Pawel; Hausgen, Paul E.; Merrill, John; Senft, Donna; Piszczor, Michael F., Jr.

2007-01-01

This paper gives an overview of the space plasma test program for thin-film photovoltaics (TFPV) technologies developed at the Air Force Research Laboratory (AFRL). The main objective of this program is to simulate the effects of space plasma characteristic of LEO and MEO environments on TFPV. Two types of TFPV, amorphous silicon (a-Si) and copper-indium-gallium-diselenide (CIGS), coated with two types of thin-film, multifunctional coatings were used for these studies. This paper reports the results of the first phase of this program, namely the results of preliminary electrostatic charging, arcing, dielectric breakdown, and collection current measurements carried out with a series of TFPV exposed to simulated space plasma at the NASA Glenn Plasma Interaction Facility. The experimental data demonstrate that multifunctional coatings developed for this program provide effective protection against the plasma environment while minimizing impact on power generation performance. This effort is part of an ongoing program led by the Space Vehicles Directorate at the AFRL devoted to the development and space qualification of TFPV and their protective coatings.

Cluster synthesis of monodisperse rutile-TiO2 nanoparticles and dielectric TiO2-vinylidene fluoride oligomer nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balasubramanian, B; Kraemer, KL; Valloppilly, SR

2011-09-13

The embedding of oxide nanoparticles in polymer matrices produces a greatly enhanced dielectric response by combining the high dielectric strength and low loss of suitable host polymers with the high electric polarizability of nanoparticles. The fabrication of oxide-polymer nanocomposites with well-controlled distributions of nanoparticles is, however, challenging due to the thermodynamic and kinetic barriers between the polymer matrix and nanoparticle fillers. In the present study, monodisperse TiO2 nanoparticles having an average particle size of 14.4 nm and predominant rutile phase were produced using a cluster-deposition technique without high-temperature thermal annealing and subsequently coated with uniform vinylidene fluoride oligomer (VDFO) moleculesmore » using a thermal evaporation source, prior to deposition as TiO2-VDFO nanocomposite films on suitable substrates. The molecular coatings on TiO2 nanoparticles serve two purposes, namely to prevent the TiO2 nanoparticles from contacting each other and to couple the nanoparticle polarization to the matrix. Parallel-plate capacitors made of TiO2-VDFO nanocomposite film as the dielectric exhibit minimum dielectric dispersion and low dielectric loss. Dielectric measurements also show an enhanced effective dielectric constant in TiO2-VDFO nanocomposites as compared to that of pure VDFO. This study demonstrates for the first time a unique electroactive particle coating in the form of a ferroelectric VDFO that has high-temperature stability as compared to conventionally used polymers for fabricating dielectric oxide-polymer nanocomposites.« less

In situ chemical oxidative polymerization preparation of poly(3,4-ethylenedioxythiophene)/graphene nanocomposites with enhanced thermoelectric performance.

PubMed

Xu, Kongli; Chen, Guangming; Qiu, Dong

2015-05-01

Three different in situ chemical oxidative polymerization routes, that is, (A) spin-coating and subsequent liquid layer polymerization, (B) spin-coating followed by vapor phase polymerization, and (C) in situ polymerization and then post-treatment by immersion in ethylene glycol (EG), have been developed to achieve poly(3,4-ethylenedioxythiophene)/reduced graphene oxide (PEDOT/rGO) nanocomposites. As demonstrated by scanning electron microscopic and energy-dispersive X-ray spectroscopic techniques, PEDOT has been successfully coated on the surface of the rGO nanosheets by each of the three preparation routes. Importantly, all of the nanocomposites display a greatly enhanced thermoelectric performance (power factors) relative to those of the corresponding neat PEDOT. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication and characterization of chitosan nanoparticles and collagen-loaded polyurethane nanocomposite membrane coated with heparin for atrial septal defect (ASD) closure.

PubMed

Kaiser, Eva; Jaganathan, Saravana Kumar; Supriyanto, Eko; Ayyar, Manikandan

2017-07-01

Atrial septal defect (ASD) constitutes 30-40% of all congenital heart diseases in adults. The most common complications in the treatment of ASD are embolization of the device and thrombosis formation. In this research, an occluding patch was developed for ASD treatment using a well-known textile technology called electrospinning. For the first time, a cardiovascular occluding patch was fabricated using medical grade polyurethane (PU) loaded with bioactive agents namely chitosan nanoparticles (Cn) and collagen (Co) which is then coated with heparin (Hp). Fourier transform infrared spectrum showed characteristic vibrations of several active constituents and changes in the absorbance due to the inclusion of active ingredients in the patch. The contact angle analysis demonstrated no significant decrease in contact angle compared to the control and the composite patches. The structure of the electrospun nanocomposite (PUCnCoHp) was examined through scanning electron microscopy. A decrease in nanofiber diameter between control PU and PUCnCoHp nanocomposite was observed. Water uptake was found to be decreased for the PUCnCoHp nanocomposite against the control. The hemocompatibility properties of the PUCnCoHp ASD occluding patch was inferred through in vitro hemocompatibility tests like activated partial thromboplastin time (APTT), prothrombin time (PT) and hemolysis assay. It was found that the PT and APTT time was significantly prolonged for the fabricated PUCnCoHp ASD occluding patch compared to the control. Likewise, the hemolysis percentage was also decreased for the PUCnCoHp ASD patch against the control. In conclusion, the developed PUCnCoHp patch demonstrates potential properties to be used for ASD occlusion.

An environmentally compliant cerium-based conversion coating for aluminum protection

NASA Astrophysics Data System (ADS)

Lin, Xuan

Chromate conversion coatings have been extensively used in the aircraft industry for the corrosion protection of aluminum alloys. Unfortunately, hexavalent chromium, which is a primary component in the chromating process, is a confirmed carcinogen. Because of rising remediation and disposal costs caused by increasingly strict regulations, the replacement of the traditional chromate conversion process is becoming a top priority in the metal finishing industry. This research focused on the electrodeposition of cerium-based coatings on 7075-T6 aluminum alloy in an electrolyte containing a cerium salt, an oxidizing agent and an organic solvent. The cerium-rich deposits were characterized by phase composition, oxidation state, coating thickness, surface morphology, deposition mechanism and polarization behavior. Chemical and electrochemical tests were utilized to compare the corrosion resistance between cerium-based coatings and chromate conversion coatings. To characterize and simulate the deposition process, a variety of approaches were utilized to study the oxidation states of cerium in various soluble and precipitated forms as a function of hydrogen peroxide and electrolyte pH. The pH ranges where the oxidation and reduction reactions dominate were determined. Further studies were performed to optimize the corrosion performance of cerium-based coatings and to understand the effects of electrolyte constituents and deposition parameters. The optimum levels for these variables were identified. A patent disclosure on the cerium-based coating process was made to the University of Missouri-Rolla and has now been officially filed with the U.S. Patent Office.

Natural organic UV-absorbent coatings based on cellulose and lignin: designed effects on spectroscopic properties.

PubMed

Hambardzumyan, Arayik; Foulon, Laurence; Chabbert, Brigitte; Aguié-Béghin, Véronique

2012-12-10

Novel nanocomposite coatings composed of cellulose nanocrystals (CNCs) and lignin (either synthetic or fractionated from spruce and corn stalks) were prepared without chemical modification or functionalization (via covalent attachment) of one of the two biopolymers. The spectroscopic properties of these coatings were investigated by UV-visible spectrophotometry and spectroscopic ellipsometry. When using the appropriate weight ratio of CNC/lignin (R), these nanocomposite systems exhibited high-performance optical properties, high transmittance in the visible spectrum, and high blocking in the UV spectrum. Atomic force microscopy analysis demonstrated that these coatings were smooth and homogeneous, with visible dispersed lignin nodules in a cellulosic matrix. It was also demonstrated that the introduction of nanoparticles into the medium increases the weight ratio and the CNC-specific surface area, which allows better dispersion of the lignin molecules throughout the solid film. Consequently, the larger molecular expansion of these aromatic polymers on the surface of the cellulosic nanoparticles dislocates the π-π aromatic aggregates, which increases the extinction coefficient and decreases the transmittance in the UV region. These nanocomposite coatings were optically transparent at visible wavelengths.

Improved Dental Implant Drill Durability and Performance Using Heat and Wear Resistant Protective Coatings.

PubMed

Er, Nilay; Alkan, Alper; Ilday, Serim; Bengu, Erman

2018-06-01

The dental implant drilling procedure is an essential step for implant surgery, and frictional heat in bone during drilling is a key factor affecting the success of an implant. The aim of this study was to increase the dental implant drill lifetime and performance by using heat- and wear-resistant protective coatings to decrease the alveolar bone temperature caused by the dental implant drilling procedure. Commercially obtained stainless steel drills were coated with titanium aluminum nitride, diamond-like carbon, titanium boron nitride, and boron nitride coatings via magnetron-sputter deposition. Drilling was performed on bovine femoral cortical bone under the conditions mimicking clinical practice. Tests were performed under water-assisted cooling and under the conditions when no cooling was applied. Coated drill performances and durabilities were compared with those of three commonly used commercial drills with surfaces made from zirconia, black diamond. and stainless steel. Protective coatings with boron nitride, titanium boron nitride, and diamond-like carbon have significantly improved drill performance and durability. In particular, boron nitride-coated drills have performed within safe bone temperature limits for 50 drillings even when no cooling is applied. Titanium aluminium nitride coated drills did not show any improvement over commercially obtained stainless steel drills. Surface modification using heat- and wear-resistant coatings is an easy and highly effective way to improve implant drill performance and durability, which can improve the surgical procedure and the postsurgical healing period. The noteworthy success of different types of coatings is novel and likely to be applicable to various other medical systems.

Sol-gel dip coating of yttria-stabilized tetragonal zirconia dental ceramic by aluminosilicate nanocomposite as a novel technique to improve the bonding of veneering porcelain.

PubMed

Madani, Azamsadat; Nakhaei, Mohammadreza; Karami, Parisa; Rajabzadeh, Ghadir; Salehi, Sahar; Bagheri, Hossein

2016-01-01

The aim of this in vitro study was to evaluate the effect of silica and aluminosilicate nanocomposite coating of zirconia-based dental ceramic by a sol-gel dip-coating technique on the bond strength of veneering porcelain to the yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in vitro. Thirty Y-TZP blocks (10 mm ×10 mm ×3 mm) were prepared and were assigned to four experimental groups (n=10/group): C, without any further surface treatment as the control group; S, sandblasted using 110 μm alumina powder; Si, silica sol dip coating + calcination; and Si/Al, aluminosilicate sol dip coating + calcination. After preparing Y-TZP samples, a 3 mm thick layer of the recommended porcelain was fired on the coated Y-TZP surface. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis were used to characterize the coating and the nature of the bonding between the coating and zirconia. To examine the zirconia-porcelain bond strength, a microtensile bond strength (μTBS) approach was chosen. FT-IR study showed the formation of silica and aluminosilicate materials. XRD pattern showed the formation of new phases consisting of Si, Al, and Zr in coated samples. SEM showed the formation of a uniform coating on Y-TZP samples. Maximum μTBS values were obtained in aluminosilicate samples, which were significantly increased compared to control and sandblasted groups (P=0.013 and P<0.001, respectively). This study showed that aluminosilicate sol-gel dip coating can be considered as a convenient, less expensive reliable method for improving the bond strength between dental Y-TZP ceramics and veneering porcelain.

Antibacterial Property of Cold-Sprayed HA-Ag/PEEK Coating

NASA Astrophysics Data System (ADS)

Sanpo, Noppakun; Tan, Meng Lu; Cheang, Philip; Khor, K. A.

2009-03-01

The antibacterial behavior of HA-Ag (silver-doped hydroxyapatite) nanopowder and their composite coatings were investigated against Escherichia coli (DH5α). HA-Ag nanopowder and PEEK (poly-ether-ether-ketone)-based HA-Ag composite powders were synthesized using in-house powder processing techniques. Bacteria culture assay of HA-Ag nanopowder and their composite powders displayed excellent bacteriostatic activity against E. coli. The antibacterial activity increased with increasing concentration of HA-Ag nanoparticle in these composite powders. These nanocomposite powders were subsequently used as feedstock to generate antibacterial coatings via cold spray technology. The ratios of HA-Ag to PEEK in their composite powders were 80:20, 60:40, 40:60, and 20:80 (wt.%). Microstructural characterization and phase analysis of feedstock powders and as-deposited coatings were carried out using FESEM/EDX and XRD. Antibacterial nanocomposite HA-Ag/PEEK coatings were successfully deposited using cold spraying parameters of 11-12 bars at preheated air temperature between 150 and 160 °C. These as-sprayed coatings of HA-Ag/PEEK composite powders comprising varying HA-Ag and PEEK ratios retained their inherent antibacterial property as verified from bacterial assay. The results indicated that the antibacterial activity increased with increasing HA-Ag nanopowder concentration in the composite powder feedstock and cold-sprayed coating.

Laboratory investigation of fire protection coatings for creosote-treated timber railroad bridges

Treesearch

Carol A. Clausen; Robert H. White; James P. Wacker; Stan T. Lebow; Mark A. Dietenberger; Samuel L. Zelinka; Nicole M. Stark

2014-01-01

As the incidence of timber railroad bridge fires increases, so has the need to develop protective measures to reduce the risk from accidental ignitions primarily caused by hot metal objects. Of the six barrier treatments evaluated in the laboratory for their ability to protect timbers from fires sourced with ignition from hot metal objects only one intumescent coating...

Electrochemical detection of Hg (II) ions using EDTA-PANI/SWNTs nanocomposite modified SS electrode

NASA Astrophysics Data System (ADS)

Deshmukh, M. A.; Patil, H. K.; Shirsat, M. D.; Ramanavicius, A.

2017-05-01

Detection of Hg (II) ions using EDTA modified polyaniline (PANI) and single walled carbon nanotubes (SWNTs) nanocomposite (PANI/SWNTs) was performed electrochemically via cyclic voltammetry (CV) technique. Dodecyl benzene sulphonic next step, PANI/SWNTs nanocomposite was modified acid sodium salt (DBSA) was used as a surfactant during this synthesis to get uniform suspension SWNTs. In the by EDTA solution containing crosslinking agent 1-ethyl-3(3-(dimethylamino) propyl) - carbodiimide (EDC) utilizing dip coating technique. The sensitivity of EDTA modified PANI/SWNTs nanocomposite towards Hg (II) ions was investigated. Differential pulse voltammetry (DPV) technique was applied for the electrochemical detection of Hg (II) ions.

Tribological properties of TiC/a-C:H nanocomposite coatings prepared via HiPIMS

NASA Astrophysics Data System (ADS)

Sánchez-López, J. C.; Dominguez-Meister, S.; Rojas, T. C.; Colasuonno, M.; Bazzan, M.; Patelli, A.

2018-05-01

High power impulse magnetron sputtering (HiPIMS) technology has been employed to prepare TiC/a-C:H nanocomposite coatings from a titanium target in acetylene (C2H2) reactive atmospheres. Gas fluxes were varied from 1.3 to 4.4 sccm to obtain C/Ti ratios from 2 to 15 as measured by electron probe microanalysis (EPMA). X-ray diffraction and transmission electron microscopy demonstrate the presence of TiC nanocrystals embedded in an amorphous carbon-based matrix. The hardness properties decrease from 17 to 10 GPa as the carbon content increases. The tribological properties were measured using a pin-on-disk tribometer in ambient air (RH = 30-40%) at 10 cm/s with 5 N of applied load against 6-mm 100Cr6 balls. The friction coefficient and the film wear rates are gradually improved from 0.3 and 7 × 10-6 mm3/N m to 0.15 and 2 × 10-7 mm3/N m, respectively, by increasing the C2H2 flux. To understand the tribological processes appearing at the interface and to elucidate the wear mechanism, microstructural and chemical investigations of the coatings were performed before and after the friction test. EPMA, X-ray photoelectron and electron energy-loss spectroscopies were employed to obtain an estimation of the fraction of the a-C:H phase, which can be correlated with the tribological behavior. Examination of the friction counterfaces (ball and track) by Raman microanalysis reveals an increased ordering of the amorphous carbon phase concomitant with friction reduction. The tribological results were compared with similar TiC/a-C(:H) composites prepared by the conventional direct current process.

Improved Electrochemical Performance of LiFePO4@N-Doped Carbon Nanocomposites Using Polybenzoxazine as Nitrogen and Carbon Sources.

PubMed

Wang, Ping; Zhang, Geng; Li, Zhichen; Sheng, Wangjian; Zhang, Yichi; Gu, Jiangjiang; Zheng, Xinsheng; Cao, Feifei

2016-10-03

Polybenzoxazine is used as a novel carbon and nitrogen source for coating LiFePO 4 to obtain LiFePO 4 @nitrogen-doped carbon (LFP@NC) nanocomposites. The nitrogen-doped graphene-like carbon that is in situ coated on nanometer-sized LiFePO 4 particles can effectively enhance the electrical conductivity and provide fast Li + transport paths. When used as a cathode material for lithium-ion batteries, the LFP@NC nanocomposite (88.4 wt % of LiFePO 4 ) exhibits a favorable rate performance and stable cycling performance.

Biochar-based nano-composites for the decontamination of wastewater: A review.

PubMed

Tan, Xiao-Fei; Liu, Yun-Guo; Gu, Yan-Ling; Xu, Yan; Zeng, Guang-Ming; Hu, Xin-Jiang; Liu, Shao-Bo; Wang, Xin; Liu, Si-Mian; Li, Jiang

2016-07-01

Synthesizing biochar-based nano-composites can obtain new composites and combine the advantages of biochar with nano-materials. The resulting composites usually exhibit great improvement in functional groups, pore properties, surface active sites, catalytic degradation ability and easy to separation. These composites have excellent abilities to adsorb a range of contaminants from aqueous solutions. Particularly, catalytic material-coated biochar can exert simultaneous adsorption and catalytic degradation function for organic contaminants removal. Synthesizing biochar-based nano-composites has become an important practice for expanding the environmental applications of biochar and nanotechnology. This paper aims to review and summarize the various synthesis techniques for biochar-based nano-composites and their effects on the decontamination of wastewater. The characteristic and advantages of existing synthesis methods are summarized and discussed. Application of biochar-based nano-composites for different contaminants removal and the underlying mechanisms are reviewed. Furthermore, knowledge gaps that exist in the fabrication and application of biochar-based nano-composites are also identified. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thin Coatings of Polymeric Carbon and Carbon Nanotubes for Corrosion Protection

DTIC Science & Technology

2009-02-01

Thin Coatings of Polymeric Carbon and Carbon Nanotubes for Corrosion Protection Zafar Iqbal Department of Chemistry and Environmental Science New...Department of Chemistry and Environmental Science ,Newark,NJ,07102 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND

Expedient Encapsulation: Protective Structural Coatings