PbO networks composed of single crystalline nanosheets synthesized by a facile chemical precipitation method

Energy Technology Data Exchange (ETDEWEB)

Samberg, Joshua P. [Department of Materials Science and Engineering, North Carolina State University, 911 Partners Way, Engineering Building I, Raleigh, NC 27695-7907 (United States); Kajbafvala, Amir, E-mail: amir.kajbafvala@gmail.com [Department of Materials Science and Engineering, North Carolina State University, 911 Partners Way, Engineering Building I, Raleigh, NC 27695-7907 (United States); Koolivand, Amir [Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695 (United States)

2014-03-01

Graphical abstract: - Highlights: • Synthesis of PbO networks through a simple chemical precipitation route. • The synthesis method is rapid and low-cost. • Each network is composed of single crystalline PbO nanosheets. • A possible growth mechanism is proposed for synthesized PbO networks. - Abstract: For the field of energy storage, nanostructured lead oxide (PbO) shows immense potential for increased specific energy and deep discharge for lead acid battery technologies. In this work, PbO networks composed of single crystalline nanosheets were synthesized utilizing a simple, low cost and rapid chemical precipitation method. The PbO networks were prepared in a single reaction vessel from starting reagents of lead acetate dehydrate, ammonium hydroxide and deionized water. Lead acetate dehydrate was chosen as a reagent, as opposed to lead nitrate, to eliminate the possibility of nitrate contamination of the final product. X-ray diffraction (XRD) analysis, high resolution scanning electron microscopy (HRSEM) and high resolution transmission electron microscopy (HRTEM) analysis were used to characterize the synthesized PbO networks. The reproducible method described herein synthesized pure β-PbO (massicot) powders, with no byproducts. A possible formation mechanism for these PbO networks is proposed. The growth is found to proceed predominately in the 〈1 1 1〉 and 〈2 0 0〉 directions while being limited in the 〈0 1 1〉 direction.

PbO networks composed of single crystalline nanosheets synthesized by a facile chemical precipitation method

International Nuclear Information System (INIS)

Samberg, Joshua P.; Kajbafvala, Amir; Koolivand, Amir

2014-01-01

Graphical abstract: - Highlights: • Synthesis of PbO networks through a simple chemical precipitation route. • The synthesis method is rapid and low-cost. • Each network is composed of single crystalline PbO nanosheets. • A possible growth mechanism is proposed for synthesized PbO networks. - Abstract: For the field of energy storage, nanostructured lead oxide (PbO) shows immense potential for increased specific energy and deep discharge for lead acid battery technologies. In this work, PbO networks composed of single crystalline nanosheets were synthesized utilizing a simple, low cost and rapid chemical precipitation method. The PbO networks were prepared in a single reaction vessel from starting reagents of lead acetate dehydrate, ammonium hydroxide and deionized water. Lead acetate dehydrate was chosen as a reagent, as opposed to lead nitrate, to eliminate the possibility of nitrate contamination of the final product. X-ray diffraction (XRD) analysis, high resolution scanning electron microscopy (HRSEM) and high resolution transmission electron microscopy (HRTEM) analysis were used to characterize the synthesized PbO networks. The reproducible method described herein synthesized pure β-PbO (massicot) powders, with no byproducts. A possible formation mechanism for these PbO networks is proposed. The growth is found to proceed predominately in the 〈1 1 1〉 and 〈2 0 0〉 directions while being limited in the 〈0 1 1〉 direction

Surface microstructure and in vitro analysis of nanostructured akermanite (Ca2MgSi2O7) coating on biodegradable magnesium alloy for biomedical applications.

Science.gov (United States)

Razavi, Mehdi; Fathi, Mohammadhossein; Savabi, Omid; Hashemi Beni, Batoul; Vashaee, Daryoosh; Tayebi, Lobat

2014-05-01

Magnesium (Mg) alloys, owing to their biodegradability and good mechanical properties, have potential applications as biodegradable orthopedic implants. However, several poor properties including low corrosion resistance, mechanical stability and cytocompatibility have prevented their clinical application, as these properties may result in the sudden failure of the implants during the bone healing. In this research, nanostructured akermanite (Ca2MgSi2O7) powder was coated on the AZ91 Mg alloy through electrophoretic deposition (EPD) assisted micro arc oxidation (MAO) method to modify the properties of the alloy. The surface microstructure of coating, corrosion resistance, mechanical stability and cytocompatibility of the samples were characterized with different techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electrochemical corrosion test, immersion test, compression test and cell culture test. The results showed that the nanostructured akermanite coating can improve the corrosion resistance, mechanical stability and cytocompatibility of the biodegradable Mg alloy making it a promising material to be used as biodegradable bone implants for orthopedic applications. Published by Elsevier B.V.

Hot corrosion behavior of nanostructured Gd2O3 doped YSZ thermal barrier coating in presence of Na2SO4 + V2O5 molten salts

Directory of Open Access Journals (Sweden)

Yixiong Wang

2017-08-01

Full Text Available Nickel-based superalloy DZ125 was first sprayed with a NiCrAlY bond coat and followed with a nanostructured 2 mol% Gd2O3−4.5 mol% Y2O3-ZrO2 (2GdYSZ topcoat using air plasma spraying (APS. Hot corrosion behavior of the as-sprayed thermal barrier coatings (TBCs were investigated in the presence of 50 wt% Na2SO4 + 50 wt% V2O5 as the corrosive molten salt at 900 °C for 100 h. The analysis results indicate that Gd doped YVO4 and m-ZrO2 crystals were formed as corrosion products due to the reaction of the corrosive salts with stabilizers (Y2O3, Gd2O3 of zirconia. Cross-section morphology shows that a thin layer called TGO was formed at the bond coat/topcoat interface. After hot corrosion test, the proportion of m-ZrO2 phase in nanostructured 2GdYSZ coating is lower than that of nano-YSZ coating. The result reveals that nanostructured 2GdYSZ coating exhibits a better hot corrosion resistance than nano-YSZ coating.

Characterization of gas tunnel type plasma sprayed hydroxyapatite-nanostructure titania composite coatings

Science.gov (United States)

Yugeswaran, S.; Kobayashi, A.; Ucisik, A. Hikmet; Subramanian, B.

2015-08-01

Hydroxyapatite (HA) can be coated onto metal implants as a ceramic biocompatible coating to bridge the growth between implants and human tissue. Meanwhile many efforts have been made to improve the mechanical properties of the HA coatings without affecting its bioactivity. In the present study, nanostructure titania (TiO2) was mixed with HA powder and HA-nanostructure TiO2 composite coatings were produced by gas tunnel type plasma spraying torch under optimized spraying conditions. For this purpose, composition of 10 wt% TiO2 + 90 wt% HA, 20 wt% TiO2 + 80 wt% HA and 30 wt% TiO2 + 70 wt% HA were selected as the feedstock materials. The phase, microstructure and mechanical properties of the coatings were characterized. The obtained results validated that the increase in weight percentage of nanostructure TiO2 in HA coating significantly increased the microhardness, adhesive strength and wear resistance of the coatings. Analysis of the in vitro bioactivity and cytocompatibility of the coatings were done using conventional simulated body fluid (c-SBF) solution and cultured green fluorescent protein (GFP) labeled marrow stromal cells (MSCs) respectively. The bioactivity results revealed that the composite coating has bio-active surface with good cytocompatibility.

Enhanced ductility in thermally sprayed titania coating synthesized using a nanostructured feedstock

International Nuclear Information System (INIS)

Lima, R.S.; Marple, B.R.

2005-01-01

Nanostructured and conventional titania (TiO 2 ) feedstock powders were thermally sprayed via high velocity oxy-fuel (HVOF). The microstructure, porosity, Vickers hardness, crack propagation resistance, bond strength (ASTM C633), abrasion behavior (ASTM G65) and the wear scar characteristics of these two types of coatings were analyzed and compared. The coating made from the nanostructured feedstock exhibited a bimodal microstructure, with regions containing particles that were fully molten (conventional matrix) and regions with embedded particles that were semi-molten (nanostructured zones) during the thermal spraying process. The bimodal coating also exhibited higher bond strength and higher wear resistance when compared to the conventional coating. By comparing the wear scars of both coatings (via scanning electron microscopy and roughness measurements) it was observed that when the coatings were subjected to the same abrasive conditions the wear scar of the bimodal coating was smoother, with more plastically deformed regions than the conventional coating. It was concluded that this enhanced ductility of the bimodal coating was caused by its higher toughness. The results suggest that nanostructured zones randomly distributed in the microstructure of the bimodal coating act as crack arresters, thereby enhancing toughness and promoting higher critical depth of cut, which provides a broader plastic deformation range than that exhibited by the conventional coating. This work provides evidence that the enhanced ductility of the bimodal coating is a nanostructured-related property, not caused by any other microstructural artifact

A study of the nanostructure and hardness of electron beam evaporated TiAlBN Coatings

Energy Technology Data Exchange (ETDEWEB)

Baker, M.A., E-mail: m.baker@surrey.ac.u [The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); Monclus, M.A. [National Physical Laboratory, Hampton Road, Teddington, TW11 0LW (United Kingdom); Rebholz, C. [Department of Mechanical and Manufacturing Engineering, University of Cyprus, 1678 Nicosia (Cyprus); Gibson, P.N. [Institute for Health and Consumer Protection, Joint Research Centre, I-21027 Ispra (Italy); Leyland, A.; Matthews, A. [Department of Engineering Materials, University of Sheffield, Sheffield S1 3JD (United Kingdom)

2010-05-31

TiAlBN coatings have been deposited by electron beam (EB) evaporation from a single TiAlBN material source onto AISI 316 stainless steel substrates at a temperature of 450 {sup o}C and substrate bias of - 100 V. The stoichiometry and nanostructure have been studied by X-ray photoelectron spectroscopy, X-ray diffraction and transmission electron microscopy. The hardness and elastic modulus were determined by nanoindentation. Five coatings have been deposited, three from hot-pressed TiAlBN material and two from hot isostatically pressed (HIPped) material. The coatings deposited from the hot-pressed material exhibited a nanocomposite nc-(Ti,Al)N/a-BN/a-(Ti,Al)B{sub 2} structure, the relative phase fraction being consistent with that predicted by the equilibrium Ti-B-N phase diagram. Nanoindentation hardness values were in the range of 22 to 32 GPa. Using the HIPped material, coating (Ti,Al)B{sub 0.29}N{sub 0.46} was found to have a phase composition of 72-79 mol.% nc-(Ti,Al)(N,B){sub 1-x}+ 21-28 mol.% amorphous titanium boride and a hardness of 32 GPa. The second coating, (Ti,Al)B{sub 0.66}N{sub 0.25}, was X-ray amorphous with a nitride+boride multiphase composition and a hardness of 26 GPa. The nanostructure and structure-property relationships of all coatings are discussed in detail. Comparisons are made between the single-EB coatings deposited in this work and previously deposited twin-EB coatings. Twin-EB deposition gives rise to lower adatom mobilities, leading to (111) (Ti,Al)N preferential orientation, smaller grain sizes, less dense coatings and lower hardnesses.

Hafnia-Based Nanostructured Thermal Barrier Coatings for Advanced Hydrogen Turbine Technology

Energy Technology Data Exchange (ETDEWEB)

Ramana, Chintalapalle; Choudhuri, Ahsan

2013-01-31

Thermal barrier coatings (TBCs) are critical technologies for future gas turbine engines of advanced coal based power generation systems. TBCs protect engine components and allow further increase in engine temperatures for higher efficiency. In this work, nanostructured HfO{sub 2}-based coatings, namely Y{sub 2}O{sub 3}-stabilized HfO{sub 2} (YSH), Gd{sub 2}O{sub 3}-stabilized HfO{sub 2} (GSH) and Y{sub 2}O{sub 3}-stabilized ZrO{sub 2}-HfO{sub 2} (YSZH) were investigated for potential TBC applications in hydrogen turbines. Experimental efforts are aimed at creating a fundamental understanding of these TBC materials. Nanostructured ceramic coatings of YSH, GSH and YSZH were grown by physical vapor deposition methods. The effects of processing parameters and ceramic composition on the microstructural evolution of YSH, GSH and YSZH nanostructured coatings was studied using combined X-ray diffraction (XRD) and Electron microscopy analyses. Efforts were directed to derive a detailed understanding of crystal-structure, morphology, and stability of the coatings. In addition, thermal conductivity as a function of composition in YSH, YSZH and GSH coatings was determined. Laboratory experiments using accelerated test environments were used to investigate the relative importance of various thermo-mechanical and thermo-chemical failure modes of TBCs. Effects of thermal cycling, oxidation and their complex interactions were evaluated using a syngas combustor rig.

Development of a hard nano-structured multi-component ceramic coating by laser cladding

International Nuclear Information System (INIS)

Masanta, Manoj; Ganesh, P.; Kaul, Rakesh; Nath, A.K.; Roy Choudhury, A.

2009-01-01

The present paper reports laser-assisted synthesis of a multi-component ceramic composite coating consisting of aluminum oxide, titanium di-boride and titanium carbide (Al 2 O 3 -TiB 2 -TiC). A pre-placed powder mixture of aluminum (Al), titanium oxide (TiO 2 ) and boron carbide (B 4 C) was made to undergo self-propagating high-temperature synthesis (SHS) by laser triggering. Laser subsequently effected cladding of the products of SHS on the substrate. The effect of laser scanning speed on the hardness, microstructure and phase composition of the composite coating was investigated. The coating exhibited an increase in hardness and a decrease in grain size with increase in laser scanning speed. A maximum micro-hardness of 2500 HV 0.025 was obtained. X-ray diffraction (XRD) of the top surface of the coating revealed the presence of aluminum oxide (Al 2 O 3 ), titanium di-boride (TiB 2 ) and titanium carbide (TiC) along with some non-stoichiometric products of the Ti-Al-B-C-O system. Field emission gun scanning electron microscopy (FESEM) and high-resolution transmission electron microscopic (HRTEM) analysis revealed some nano-structured TiB 2 and Al 2 O 3 , which are discussed in detail.

Analysis of the first temperate broad host range brucellaphage (BiPBO1 isolated from B. inopinata

Directory of Open Access Journals (Sweden)

Jens Andre Hammerl

2016-01-01

Full Text Available Brucella species are important human and animal pathogens. Though, only little is known about mobile genetic elements of these highly pathogenic bacteria. To date, neither plasmids nor temperate phages have been described in brucellae. We analysed genomic sequences of various reference and type strains and identified a number of putative prophages residing within the Brucella chromosomes. By induction, phage BiPBO1 was isolated from B. inopinata. BiPBO1 is a siphovirus that infects several Brucella species including B. abortus and B. melitensis. Integration of the phage genome occurs adjacent to a tRNA gene in chromosome 1 (chr 1. The bacterial (attB and phage (attP attachment sites comprise an identical sequence of 46 bp. This sequence exists in many Brucella and Ochrobactrum species. The BiPBO1 genome is composed of a 46,877 bp double-stranded DNA. Eighty-seven putative gene products were determined, of which 32 could be functionally assigned. Strongest similarities were found to a temperate phage residing in the chromosome of Ochrobactrum anthropi ATCC 49188 and to prophages identified in several families belonging to the order rhizobiales. The data suggest that horizontal gene transfer may occur between Brucella and Ochrobactrum and underpin the close relationship of these environmental and pathogenic bacteria.

Development of a hard nano-structured multi-component ceramic coating by laser cladding

Energy Technology Data Exchange (ETDEWEB)

Masanta, Manoj [Department of Mechanical Engineering, IIT Kharagpur, West Bengal 721302 (India); Ganesh, P.; Kaul, Rakesh [Laser Material Processing Division, Raja Ramanna Centre for Advanced Technology, Indore (India); Nath, A.K. [Department of Mechanical Engineering, IIT Kharagpur, West Bengal 721302 (India); Roy Choudhury, A., E-mail: roychoudhuryasimava@gmail.com [Department of Mechanical Engineering, IIT Kharagpur, West Bengal 721302 (India)

2009-05-20

The present paper reports laser-assisted synthesis of a multi-component ceramic composite coating consisting of aluminum oxide, titanium di-boride and titanium carbide (Al{sub 2}O{sub 3}-TiB{sub 2}-TiC). A pre-placed powder mixture of aluminum (Al), titanium oxide (TiO{sub 2}) and boron carbide (B{sub 4}C) was made to undergo self-propagating high-temperature synthesis (SHS) by laser triggering. Laser subsequently effected cladding of the products of SHS on the substrate. The effect of laser scanning speed on the hardness, microstructure and phase composition of the composite coating was investigated. The coating exhibited an increase in hardness and a decrease in grain size with increase in laser scanning speed. A maximum micro-hardness of 2500 HV{sub 0.025} was obtained. X-ray diffraction (XRD) of the top surface of the coating revealed the presence of aluminum oxide (Al{sub 2}O{sub 3}), titanium di-boride (TiB{sub 2}) and titanium carbide (TiC) along with some non-stoichiometric products of the Ti-Al-B-C-O system. Field emission gun scanning electron microscopy (FESEM) and high-resolution transmission electron microscopic (HRTEM) analysis revealed some nano-structured TiB{sub 2} and Al{sub 2}O{sub 3}, which are discussed in detail.

New silicate-germanate Cs2Pb2[(Si0.6Ge0.4)2O7] from the series A2Pb2[B2O7], A = K, Cs, B = Si, Ge with the umbrella-like [PbO3]4- group

Science.gov (United States)

Belokoneva, Elena L.; Morozov, Ivan A.; Volkov, Anatoly S.; Dimitrova, Olga V.; Stefanovich, Sergey Yu.

2018-04-01

New silicate-germanate Cs2Pb2[(Si0.6Ge0.4)2O7] was synthesized in multi-components hydrothermal solution with 20 w.% concentration of Cs2CO3 mineralizer, pH = 10. Novel mixed compound belongs to the structure type A2Pb2[B2O7] previously indicated for powders with A = K, B=Si or Ge. Singe crystal structure determination of Cs2Pb2[(Si0.6Ge0.4)2O7] revealed the need for the correction of the space group of the earlier suggested structural model from P-3 to P-3m1, as well as for the splitting of the Pb-atom position. Umbrella-like groups [PbO3]4- are located between [(Si,Ge)O4]4- tetrahedra in mica-like honeycomb layers and play the role of tetrahedra with the Pb-lone-pair as the forth apex. Crystal chemical comparison revealed similarities and differences with the classical structure type of α-celsian Ba[Al2Si2O8] with the tetrahedral double layer. Recently investigated nonlinear optical acentric borates Pb2(BO3)(NO3) and Pb2(BO3)Cl are both related to this structural type, possessing umbrella-like groups [PbO3]4- and honeycomb layers [Pb2(BO3)]+ with the BO3-triangles on the tetrahedral positions.

Fabrication of a novel PbO2 electrode with a graphene nanosheet interlayer for electrochemical oxidation of 2-chlorophenol

International Nuclear Information System (INIS)

Duan, Xiaoyue; Zhao, Cuimei; Liu, Wei; Zhao, Xuesong; Chang, Limin

2017-01-01

Highlights: • A novel PbO 2 electrode with a GNS interlayer (GSN-PbO 2 ) was prepared. • The GNS interlayer reduced grain size of β-PbO 2 crystals. • The GNS interlayer enhanced electrochemical activity of PbO 2 electrode. • The lifetime of GSN-PbO 2 electrode was 1.93 times that of PbO 2 electrode. • An electrochemical mineralization mechanism of 2-chlorophenol was proposed. - Abstract: A novel PbO 2 electrode with a graphene nanosheet interlayer (marked as GNS-PbO 2 ) was prepared combining electrophoretic deposition and electro-deposition technologies. The micro morphology, crystal structure and surface chemical states of GNS-PbO 2 electrodes were characterized using scanning electronic microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Their electrochemical properties and stability were determined using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), ·OH radicals test and accelerated life test, and compared with traditional PbO 2 electrodes. Besides, their potential application in the electrochemical degradation of 2-chlorophenol (2-CP) was investigated. The GNS-PbO 2 electrode possessed perfect octahedral β-PbO 2 microcrystals, and its grain size was much smaller than that of traditional PbO 2 electrode. It exhibited higher electrochemical activity than traditional PbO 2 electrode due to its larger electrochemical active surface area and stronger ·OH radicals generation ability. The service lifetime of GNS-PbO 2 electrode (107.9 h) was 1.93 times longer than that of traditional PbO 2 electrode (55.9 h). The electrochemical degradation rate constant of 2-CP on GNS-PbO 2 electrode (k app = 2.75 × 10 −2 min −1 ) is much higher than for PbO 2 electrode (k app = 1.76 × 10 −2 min −1 ). 2-CP oxidation yielded intermediates including aromatic compounds (catechol, phenol and ortho-benzoquinone) and organic acids (oxalic acid, maleic acid and

A comparative study on omnidirectional anti-reflection SiO2 nanostructure films coating by glancing angle deposition

Science.gov (United States)

Prachachet, R.; Samransuksamer, B.; Horprathum, M.; Eiamchai, P.; Limwichean, S.; Chananonnawathorn, C.; Lertvanithphol, T.; Muthitamongkol, P.; Boonruang, S.; Buranasiri, P.

2018-02-01

Fabricated omnidirectional anti-reflection nanostructure films as a one of the promising alternative solar cell applications have attracted enormous scientific and industrial research benefits to their broadband, effective over a wide range of incident angles, lithography-free and high-throughput process. Recently, the nanostructure SiO2 film was the most inclusive study on anti-reflection with omnidirectional and broadband characteristics. In this work, the three-dimensional silicon dioxide (SiO2) nanostructured thin film with different morphologies including vertical align, slant, spiral and thin films were fabricated by electron beam evaporation with glancing angle deposition (GLAD) on the glass slide and silicon wafer substrate. The morphological of the prepared samples were characterized by field-emission scanning electron microscope (FE-SEM) and high-resolution transmission electron microscope (HRTEM). The transmission, omnidirectional and birefringence property of the nanostructure SiO2 films were investigated by UV-Vis-NIR spectrophotometer and variable angle spectroscopic ellipsometer (VASE). The spectrophotometer measurement was performed at normal incident angle and a full spectral range of 200 - 2000 nm. The angle dependent transmission measurements were investigated by rotating the specimen, with incidence angle defined relative to the surface normal of the prepared samples. This study demonstrates that the obtained SiO2 nanostructure film coated on glass slide substrate exhibits a higher transmission was 93% at normal incident angle. In addition, transmission measurement in visible wavelength and wide incident angles -80 to 80 were increased in comparison with the SiO2 thin film and glass slide substrate due to the transition in the refractive index profile from air to the nanostructure layer that improve the antireflection characteristics. The results clearly showed the enhanced omnidirectional and broadband characteristic of the three dimensional Si

As(III) oxidation by MnO{sub 2} coated PEEK-WC nanostructured capsules

Energy Technology Data Exchange (ETDEWEB)

Criscuoli, Alessandra, E-mail: a.criscuoli@itm.cnr.it [Institute on Membrane Technology, ITM-CNR, Via P. Bucci Cubo 17/C, 87030 Rende (CS) (Italy); Majumdar, Swachchha [Central Glass and Ceramic Research Institute, 196, Raja S. C. Mullick Rd., 700032 Kolkata (India); Figoli, Alberto, E-mail: a.figoli@itm.cnr.it [Institute on Membrane Technology, ITM-CNR, Via P. Bucci Cubo 17/C, 87030 Rende (CS) (Italy); Sahoo, Ganesh C. [Central Glass and Ceramic Research Institute, 196, Raja S. C. Mullick Rd., 700032 Kolkata (India); Bafaro, Patrizia [Institute on Membrane Technology, ITM-CNR, Via P. Bucci Cubo 17/C, 87030 Rende (CS) (Italy); Department of Chemical Engineering and Materials, University of Calabria, Via P. Bucci Cubo 42/A, 87030 Rende (CS) (Italy); Bandyopadhyay, Sibdas [Central Glass and Ceramic Research Institute, 196, Raja S. C. Mullick Rd., 700032 Kolkata (India); Drioli, Enrico [Institute on Membrane Technology, ITM-CNR, Via P. Bucci Cubo 17/C, 87030 Rende (CS) (Italy); Department of Chemical Engineering and Materials, University of Calabria, Via P. Bucci Cubo 42/A, 87030 Rende (CS) (Italy)

2012-04-15

Highlights: Black-Right-Pointing-Pointer Successful preparation of PEEK-WC nanostructured capsules coated by MnO{sub 2}. Black-Right-Pointing-Pointer Preliminary tests of As(III) oxidation carried out in batch. Black-Right-Pointing-Pointer Complete oxidation obtained for feed concentrations of 0.1 and 0.3 ppm. - Abstract: PEEK-WC nanostructured capsules were prepared by the phase inversion technique and used as support for the coating of a manganese dioxide layer. The coating was done by a chemical treatment of the capsules followed by a thermal one. The presence of the MnO{sub 2} layer was confirmed by scanning electron microscopy (SEM), back scattering electron (BSE), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analysis. The produced capsules were, then, tested for As(III) oxidation in batch. The experiments consisted in treating 165 ml of As(III) solution with 1 g of coated capsules at fixed temperature (15 Degree-Sign C) and pH (5.7-5.8). In particular, the efficiency of the system was investigated for different As(III) concentrations (0.1, 0.3, 0.7 and 1 ppm). For feeds at lower As(III) content (0.1-0.3 ppm), tests lasted for 8 h, while prolonged runs (up to 48 h) were carried out on more concentrated solutions (0.7 and 1 ppm). The produced capsules were able to oxidize As(III) into As(V) leading to complete conversion after 3 and 4 h for feed concentrations of 0.1 and 0.3 ppm, respectively.

Enhanced protein adsorption and patterning on nanostructured latex-coated paper.

Science.gov (United States)

Juvonen, Helka; Määttänen, Anni; Ihalainen, Petri; Viitala, Tapani; Sarfraz, Jawad; Peltonen, Jouko

2014-06-01

Specific interactions of extracellular matrix proteins with cells and their adhesion to the substrate are important for cell growth. A nanopatterned latex-coated paper substrate previously shown to be an excellent substrate for cell adhesion and 2D growth was studied for directed immobilization of proteins. The nanostructured latex surface was formed by short-wavelength IR irradiation of a two-component latex coating consisting of a hydrophilic film-forming styrene butadiene acrylonitrile copolymer and hydrophobic polystyrene particles. The hydrophobic regions of the IR-treated latex coating showed strong adhesion of bovine serum albumin (cell repelling protein), fibronectin (cell adhesive protein) and streptavidin. Opposite to the IR-treated surface, fibronectin and streptavidin had a poor affinity toward the untreated pristine latex coating. Detailed characterization of the physicochemical surface properties of the latex-coated substrates revealed that the observed differences in protein affinity were mainly due to the presence or absence of the protein repelling polar and charged surface groups. The protein adsorption was assisted by hydrophobic (dehydration) interactions. Copyright © 2014 Elsevier B.V. All rights reserved.

CuO-PANI nanostructure with tunable spectral selectivity for solar selective coating application

Energy Technology Data Exchange (ETDEWEB)

Cindrella, L., E-mail: cind@nitt.edu; Prabhu, S., E-mail: sprabhuk@gmail.com

2016-08-15

Highlights: • CuO-PANI nanostructure has been reported as the solar selective absorber coating. • Solar selectivity and efficiency of the coatings have been evaluated. • PANI provides a surface texture favourable for multiple reflection. - Abstract: CuO-PANI nanostructure has been demonstrated as the solar selective absorber coating for the first time. The effortless chemical methods and easily scalable techniques such as precipitation, in-situ polymerization and spray coating were adopted for the fabrication of CuO nanorods and CuO-PANI nanostructures for solar application. The synthesis was carried out without using any template. The morphology and phase structure of fabricated CuO nanorods and CuO-PANI nanostructure coatings were studied by atomic force microscopy, scanning electron microscopy and X-ray diffraction analysis. The energy dispersive X-ray spectra and elemental mapping confirm the presence of the chosen elements in the nanostructure. The solar absorptance (α{sub s}), thermal emittance (ε{sub t}) and selectivity (ξ) of the nanostructure coatings on glass substrate were optimized to 0.94, 0.01 and 94 respectively by changing the polyaniline content on the surface of the CuO nanorods. The efficiency of the solar selective coatings were evaluated. The optimized solar absorber coating of CuO-PANI nanostructure is highly promising for its selective optical properties.

Phase equilibria and interaction between the CsCl-PbCl{sub 2}-PbO system components

Energy Technology Data Exchange (ETDEWEB)

Arkhipov, Pavel A.; Zakiryanova, Irina D. [Russian Academy of Sciences, Ekatherinburg (Russian Federation). Inst. of High Temperature Electrochemistry; Kholkina, Anna S.; Bausheva, Alexandra V.; Khudorozhkova, Anastasia O. [Russian Academy of Sciences, Ekatherinburg (Russian Federation). Inst. of High Temperature Electrochemistry; Ural Federal Univ., Ekatherinburg (Russian Federation)

2015-07-01

Thermal analysis was applied to determine liquidus temperatures in the CsCl-PbCl{sub 2}-PbO system, with the PbO concentration ranging from 0 to 20 mol%. The temperature dependence of the PbO solubility in the CsCl-PbCl{sub 2} eutectic melt was studied, and the thermodynamic parameters of the PbO dissolution were calculated. The type, morphology, and composition of oxychloride ionic groupings in the melt were determined in situ using Raman spectroscopy.

Development of Nanostructured Antireflection Coatings for Infrared and Electro-Optical Systems

Directory of Open Access Journals (Sweden)

Gopal G. Pethuraja

2017-07-01

Full Text Available Electro-optic infrared technologies and systems operating from ultraviolet (UV to long-wave infrared (LWIR spectra are being developed for a variety of defense and commercial systems applications. Loss of a significant portion of the incident signal due to reflection limits the performance of electro-optic infrared (IR sensing systems. A critical technology being developed to overcome this limitation and enhance the performance of sensing systems is advanced antireflection (AR coatings. Magnolia is actively involved in the development and advancement of nanostructured AR coatings for a wide variety of defense and commercial applications. Ultrahigh AR performance has been demonstrated for UV to LWIR spectral bands on various substrates. The AR coatings enhance the optical transmission through optical components and devices by significantly minimizing reflection losses, a substantial improvement over conventional thin-film AR coating technologies. Nanostructured AR coatings have been fabricated using a nanomanufacturable self-assembly process on substrates that are transparent for a given spectrum of interest ranging from UV to LWIR. The nanostructured multilayer structures have been designed, developed and optimized for various optoelectronic applications. The optical properties of optical components and sensor substrates coated with AR structures have been measured and the process parameters fine-tuned to achieve a predicted high level of performance. In this paper, we review our latest work on high quality nanostructure-based AR coatings, including recent efforts on the development of nanostructured AR coatings on IR substrates.

Coating of biodegradable magnesium alloy bone implants using nanostructured diopside (CaMgSi2O6)

Science.gov (United States)

Razavi, Mehdi; Fathi, Mohammadhossein; Savabi, Omid; Beni, Batoul Hashemi; Razavi, Seyed Mohammad; Vashaee, Daryoosh; Tayebi, Lobat

2014-01-01

Magnesium alloys with their biodegradable characteristic can be a very good candidate to be used in orthopedic implants. However, magnesium alloys may corrode and degrade too fast for applications in the bone healing procedure. In order to enhance the corrosion resistance and the in vitro bioactivity of a magnesium alloy, a nanostructured diopside (CaMgSi2O6) film was coated on AZ91 magnesium alloy through combined micro-arc oxidation (MAO) and electrophoretic deposition (EPD) methods. The crystalline structures, morphologies and compositions of the coated and uncoated substrates were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy. Polarization, electrochemical impedance spectroscopy, and immersion test in simulated body fluid (SBF) were employed to evaluate the corrosion resistance and the in vitro bioactivity of the samples. The results of our investigation showed that the nanostructured diopside coating deposited on the MAO layer increases the corrosion resistance and improves the in vitro bioactivity of the biodegradable magnesium alloy.

Coating of biodegradable magnesium alloy bone implants using nanostructured diopside (CaMgSi2O6)

International Nuclear Information System (INIS)

Razavi, Mehdi; Fathi, Mohammadhossein; Savabi, Omid; Beni, Batoul Hashemi; Razavi, Seyed Mohammad; Vashaee, Daryoosh

2014-01-01

Magnesium alloys with their biodegradable characteristic can be a very good candidate to be used in orthopedic implants. However, magnesium alloys may corrode and degrade too fast for applications in the bone healing procedure. In order to enhance the corrosion resistance and the in vitro bioactivity of a magnesium alloy, a nanostructured diopside (CaMgSi 2 O 6 ) film was coated on AZ91 magnesium alloy through combined micro-arc oxidation (MAO) and electrophoretic deposition (EPD) methods. The crystalline structures, morphologies and compositions of the coated and uncoated substrates were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy. Polarization, electrochemical impedance spectroscopy, and immersion test in simulated body fluid (SBF) were employed to evaluate the corrosion resistance and the in vitro bioactivity of the samples. The results of our investigation showed that the nanostructured diopside coating deposited on the MAO layer increases the corrosion resistance and improves the in vitro bioactivity of the biodegradable magnesium alloy.

Solution precursor plasma deposition of nanostructured ZnO coatings

International Nuclear Information System (INIS)

Tummala, Raghavender; Guduru, Ramesh K.; Mohanty, Pravansu S.

2011-01-01

Highlights: → The solution precursor route employed is an inexpensive process with capability to produce large scale coatings at fast rates on mass scale production. → It is highly capable of developing tailorable nanostructures. → This technique can be employed to spray the coatings on any kind of substrates including polymers. → The ZnO coatings developed via solution precursor plasma spray process have good electrical conductivity and reflectivity properties in spite of possessing large amount of particulate boundaries, porosity and nanostructured grains. -- Abstract: Zinc oxide (ZnO) is a wide band gap semiconducting material that has various applications including optical, electronic, biomedical and corrosion protection. It is usually synthesized via processing routes, such as vapor deposition techniques, sol-gel, spray pyrolysis and thermal spray of pre-synthesized ZnO powders. Cheaper and faster synthesis techniques are of technological importance due to increased demand in alternative energy applications. Here, we report synthesis of nanostructured ZnO coatings directly from a solution precursor in a single step using plasma spray technique. Nanostructured ZnO coatings were deposited from the solution precursor prepared using zinc acetate and water/isopropanol. An axial liquid atomizer was employed in a DC plasma spray torch to create fine droplets of precursor for faster thermal treatment in the plasma plume to form ZnO. Microstructures of coatings revealed ultrafine particulate agglomerates. X-ray diffraction confirmed polycrystalline nature and hexagonal Wurtzite crystal structure of the coatings. Transmission electron microscopy studies showed fine grains in the range of 10-40 nm. Observed optical transmittance (∼65-80%) and reflectivity (∼65-70%) in the visible spectrum, and electrical resistivity (48.5-50.1 mΩ cm) of ZnO coatings are attributed to ultrafine particulate morphology of the coatings.

Solution precursor plasma deposition of nanostructured ZnO coatings

Energy Technology Data Exchange (ETDEWEB)

Tummala, Raghavender [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States); Guduru, Ramesh K., E-mail: rkguduru@umich.edu [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States); Mohanty, Pravansu S. [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States)

2011-08-15

Highlights: {yields} The solution precursor route employed is an inexpensive process with capability to produce large scale coatings at fast rates on mass scale production. {yields} It is highly capable of developing tailorable nanostructures. {yields} This technique can be employed to spray the coatings on any kind of substrates including polymers. {yields} The ZnO coatings developed via solution precursor plasma spray process have good electrical conductivity and reflectivity properties in spite of possessing large amount of particulate boundaries, porosity and nanostructured grains. -- Abstract: Zinc oxide (ZnO) is a wide band gap semiconducting material that has various applications including optical, electronic, biomedical and corrosion protection. It is usually synthesized via processing routes, such as vapor deposition techniques, sol-gel, spray pyrolysis and thermal spray of pre-synthesized ZnO powders. Cheaper and faster synthesis techniques are of technological importance due to increased demand in alternative energy applications. Here, we report synthesis of nanostructured ZnO coatings directly from a solution precursor in a single step using plasma spray technique. Nanostructured ZnO coatings were deposited from the solution precursor prepared using zinc acetate and water/isopropanol. An axial liquid atomizer was employed in a DC plasma spray torch to create fine droplets of precursor for faster thermal treatment in the plasma plume to form ZnO. Microstructures of coatings revealed ultrafine particulate agglomerates. X-ray diffraction confirmed polycrystalline nature and hexagonal Wurtzite crystal structure of the coatings. Transmission electron microscopy studies showed fine grains in the range of 10-40 nm. Observed optical transmittance ({approx}65-80%) and reflectivity ({approx}65-70%) in the visible spectrum, and electrical resistivity (48.5-50.1 m{Omega} cm) of ZnO coatings are attributed to ultrafine particulate morphology of the coatings.

Nanostructure characterization of Ni and B layers as artificial pinning centers in multilayered MgB2/Ni and MgB2/B superconducting thin films

International Nuclear Information System (INIS)

Sosiati, H.; Hata, S.; Doi, T.; Matsumoto, A.; Kitaguchi, H.; Nakashima, H.

2013-01-01

Highlights: ► Nanostructure characterization of Ni and B layers as artificial pinning centers (APCs). ► Relationship between nanostructure and J c property. ► Enhanced J c in parallel field by parallel APCs within the MgB 2 film. -- Abstract: Research on the MgB 2 /Ni and MgB 2 /B multilayer films fabricated by an electron beam (EB) evaporation technique have been extensively carried out. The critical current density, J c of MgB 2 /Ni and MgB 2 /B multilayer films in parallel fields has been suggested to be higher than that of monolayer MgB 2 film due to introducing the artificial pinning centers of nano-sized Ni and B layers. Nanostructure characterization of the artificial pinning centers in the multilayer films were examined by transmission electron microscopy (TEM) and scanning TEM (STEM-energy dispersive X-ray spectroscopy (STEM-EDS))–EDS to understand the mechanism of flux pinning. The growth of columnar MgB 2 grains along the film-thickness direction was recognized in the MgB 2 /Ni multilayer film, but not in the MgB 2 /B multilayer film. Nano-sized Ni layers were present as crystalline epitaxial layers which is interpreted that Ni atoms might be incorporated into the MgB 2 lattice to form (Mg,Ni)B 2 phase. On the other hand, nano-sized B layers were amorphous layers. Crystalline (Mg,Ni)B 2 layers worked more effectively than amorphous B-layers, providing higher flux-pinning force that resulted in higher J c of the MgB 2 /Ni multilayer film than the MgB 2 /B multilayer film

Electrode processes during the electrorefiniment of lead in the KCl-PbCl2-PbO melt

Directory of Open Access Journals (Sweden)

P. S. Pershin

2015-03-01

Full Text Available The influence of PbO addition on current efficiency during the electrorefinement of lead in the KCl-PbCl2-PbO melt was investigated. It was shown that with PbO concentration in the KCl-PbCl2 eqiumolar mixture increasing, the current efficiency of lead decreases. Electrode processes mechanism is proposed.

Nanostructured thin films and coatings functional properties

CERN Document Server

Zhang, Sam

2010-01-01

The second volume in ""The Handbook of Nanostructured Thin Films and Coatings"" set, this book focuses on functional properties, including optical, electronic, and electrical properties, as well as related devices and applications. It explores the large-scale fabrication of functional thin films with nanoarchitecture via chemical routes, the fabrication and characterization of SiC nanostructured/nanocomposite films, and low-dimensional nanocomposite fabrication and applications. The book also presents the properties of sol-gel-derived nanostructured thin films as well as silicon nanocrystals e

Electrochemical degradation of waters containing O-Toluidine on PbO2 and BDD anodes

International Nuclear Information System (INIS)

Hmani, Emna; Chaabane Elaoud, Sourour; Samet, Youssef; Abdelhedi, Ridha

2009-01-01

Electrochemical oxidation of O-Toluidine (OT) was studied by galvanostatic electrolysis using lead dioxide (PbO 2 ) and boron-doped diamond (BDD) as anodes. The influence of operating parameters, such as current density, initial concentration of OT and temperature was investigated. Measurements of chemical oxygen demand were used to follow the oxidation. The experimental data indicated that on PbO 2 and BDD anodes, OT oxidation takes place by reaction with electrogenerated hydroxyl radicals and is favoured by low current density and high temperature. Furthermore, BDD anodes offer significant advantages over PbO 2 in terms of current efficiency and oxidation rate.

High temperature oxidation behaviour of nanostructured cermet coatings in a mixed CO2 - O2 environment

Science.gov (United States)

Farrokhzad, M. A.; Khan, T. I.

2014-06-01

Nanostructured ceramic-metallic (cermet) coatings composed of nanosized ceramic particles (α-Al2O3 and TiO2) dispersed in a nickel matrix were co-electrodeposited and then oxidized at 500°C, 600°C and 700°C in a mixed gas using a Thermo-gravimetric Analysis (TGA) apparatus. The mixed gas was composed of 15% CO2, 10% O2 and 75% N2. This research investigates the effects of CO2 and O2 partial pressures on time-depended oxidation rates for coatings and compared them to the results from atmospheric oxidation under similar temperatures. The increase in partial pressure of oxygen due to the presence of CO2 at each tested temperature was calculated and correlated to the oxidation rate of the coatings. The results showed that the presence of CO2 in the system increased the oxidation rate of cermet coatings when compared to atmospheric oxidation at the same temperature. It was also shown that the increase in the oxidation rate is not the result of CO2 acting as the primary oxidant but as a secondary oxidant which results in an increase of the total partial pressure of oxygen and consequently higher oxidation rates. The WDS and XRD analyses results showed that the presence of nanosized TiO2 particles in a nickel matrix can improve oxidation behaviour of the coatings by formation of Ni-Ti compounds on oxidizing surface of the coating which was found beneficiary in reducing the oxidation rates for cermet coatings.

Uniform Fe3O4 coating on flower-like ZnO nanostructures by atomic layer deposition for electromagnetic wave absorption.

Science.gov (United States)

Wan, Gengping; Wang, Guizhen; Huang, Xianqin; Zhao, Haonan; Li, Xinyue; Wang, Kan; Yu, Lei; Peng, Xiange; Qin, Yong

2015-11-21

An elegant atomic layer deposition (ALD) method has been employed for controllable preparation of a uniform Fe3O4-coated ZnO (ZnO@Fe3O4) core-shell flower-like nanostructure. The Fe3O4 coating thickness of the ZnO@Fe3O4 nanostructure can be tuned by varying the cycle number of ALD Fe2O3. When serving as additives for microwave absorption, the ZnO@Fe3O4-paraffin composites exhibit a higher absorption capacity than the ZnO-paraffin composites. For ZnO@500-Fe3O4, the effective absorption bandwidth below -10 dB can reach 5.2 GHz and the RL values below -20 dB also cover a wide frequency range of 11.6-14.2 GHz when the coating thickness is 2.3 mm, suggesting its potential application in the treatment of the electromagnetic pollution problem. On the basis of experimental observations, a mechanism has been proposed to understand the enhanced microwave absorption properties of the ZnO@Fe3O4 composites.

Preparation and characterization of nanostructured ZrO2 coatings on dense and porous substrates

International Nuclear Information System (INIS)

Shi Jingyu; Verweij, Henk

2008-01-01

Nanostructured ZrO 2 coatings are prepared on both dense and porous substrates by wet-chemical deposition of non-agglomerated 5 nm precursor particle dispersions, followed by thermal processing. The precursor particle dispersions are made by modified emulsion precipitation and a purification treatment to remove reaction products and additives. The coatings are formed by depositing the precursor nanoparticle dispersion directly onto the substrate, followed by drying and heating at 600 deg. C. Scanning electron microscopy and cross-sectional transmission electron microscopy observations of the heat-treated coatings indicate that the ZrO 2 coating on dense Si wafer substrate has a homogeneous, dense particle packing structure with shallow meniscus-shaped depressions in the surface, and microcracks below the meniscus surface. On the other hand, coatings formed on a meso-porous γ-alumina membrane substrate are free of defects, but with a lower packing density. The mechanism of the substrate effect on the particle packing behavior and defect formation during coating deposition is discussed. It is expected that by using a thin porous substrate with reduced capillary force, a defect-free, homogenously dense-packed coating structure can be achieved

Electrochemical study and recovery of Pb using 1:2 choline chloride/urea deep eutectic solvent: A variety of Pb species PbSO4, PbO2, and PbO exhibits the analogous thermodynamic behavior

International Nuclear Information System (INIS)

Liao, Yu-Shun; Chen, Po-Yu; Sun, I-Wen

2016-01-01

Water-insoluble PbSO 4 , PbO 2 , and PbO are fairly soluble in choline chloride/urea deep eutectic solvent (ChCl/urea DES) in 1:2 molar ratio. Very interestingly, solution prepared from PbO 2 exhibits the almost identical electrochemical behavior as those from PbSO 4 and PbO, indicating that Pb(II) is formed in the DES regardless of what Pb compound is introduced. The electrochemical reduction of the Pb(II) species is determined as an irreversible process, and involves the three-dimensional (3D) instantaneous nucleation with diffusion-controlled growth. From the dependence of the diffusion coefficient on temperature, the activation energy for diffusion of PbSO 4 and PbO 2 is determined to be 33.7 and 34.1 kJ mol −1 , respectively. Electrodeposition of Pb was achieved potentiostatically and galvanostatically. The surface morphology of Pb deposits significantly depends on the applied potential and current. The coulombic efficiency of Pb electrodeposition is higher than 90%. Electrodeposition of Pb from a wet DES containing a mixture of three different Pb sources is also investigated. The XRD analysis confirmed that the electrodeposits consisted of metallic Pb.

Nanostructured glass–ceramic coatings for orthopaedic applications

Science.gov (United States)

Wang, Guocheng; Lu, Zufu; Liu, Xuanyong; Zhou, Xiaming; Ding, Chuanxian; Zreiqat, Hala

2011-01-01

Glass–ceramics have attracted much attention in the biomedical field, as they provide great possibilities to manipulate their properties by post-treatments, including strength, degradation rate and coefficient of thermal expansion. In this work, hardystonite (HT; Ca2ZnSi2O7) and sphene (SP; CaTiSiO5) glass–ceramic coatings with nanostructures were prepared by a plasma spray technique using conventional powders. The bonding strength and Vickers hardness for HT and SP coatings are higher than the reported values for plasma-sprayed hydroxyapatite coatings. Both types of coatings release bioactive calcium (Ca) and silicon (Si) ions into the surrounding environment. Mineralization test in cell-free culture medium showed that many mushroom-like Ca and phosphorus compounds formed on the HT coatings after 5 h, suggesting its high acellular mineralization ability. Primary human osteoblasts attach, spread and proliferate well on both types of coatings. Higher proliferation rate was observed on the HT coatings compared with the SP coatings and uncoated Ti-6Al-4V alloy, probably due to the zinc ions released from the HT coatings. Higher expression levels of Runx2, osteopontin and type I collagen were observed on both types of coatings compared with Ti-6Al-4V alloy, possibly due to the Ca and Si released from the coatings. Results of this study point to the potential use of HT and SP coatings for orthopaedic applications. PMID:21292725

A green preparation method of battery grade α-PbO based on Pb-O2 fuel cell

Science.gov (United States)

Wang, Pingyuan; Pan, Junqing; Gong, Shumin; Sun, Yanzhi

2017-08-01

In order to solve the problem of high pollution and high energy consumption of the current lead oxide (PbO) preparation processes, a new clean and energy saving preparation method for high purity α-PbO via discharge of a Pb-O2 fuel cell is reported. The fuel cell with metallic lead anode, oxygen cathode, and 30% NaOH electrolyte can provide a discharge voltage of 0.66-0.38 V corresponding to discharge current range of 5-50 mA cm-2. PbO is precipitated from the NaHPbO2-containing electrolyte through a cooling crystallization process after discharge process, and the XRD patterns indicate the structure is pure α-PbO. The mother liquid after crystallization can be recycled for the next batch. The obtained PbO mixed with 60% Shimadzu PbO is superior to the pure Shimadzu PbO in discharge capacity and cycle ability.

Preparation and in vitro evaluation of nanostructured TiO2/TCP composite coating by plasma electrolytic oxidation

International Nuclear Information System (INIS)

Hu, Hongjie; Liu, Xuanyong; Ding, Chuanxian

2010-01-01

Porous and nanostructured TiO 2 /tricalcium phosphate (TCP) composite coating on titanium substrate was prepared by plasma electrolytic oxidation (PEO). The microstructure and phase composition of the coating were characterized using scanning electron microscopy and X-ray diffraction. Its bioactivity was evaluated by simulated body fluid (SBF) immersion tests. MG63 cells were cultured on the surface of the coating to investigate its cytocompatibility. Potentiodynamic polarization tests were applied to measure its corrosion resistance. The results revealed that rough and hydrophilic TiO 2 /TCP composite coating with pores of several micrometers and grains of 50-200 nm was prepared by one-step PEO treatment. The TiO 2 /TCP composite coating showed good apatite-forming ability in SBF, and the TCP phase in the coating played an important role in inducing apatite formation. MG63 cells could adhere and proliferate on the surface of the coating, indicating its good cytocompatibility. The composite coating also exhibited good corrosion resistance in 0.9% NaCl solution.

Nanostructured diamond coatings for orthopaedic applications

Science.gov (United States)

CATLEDGE, S.A.; THOMAS, V.; VOHRA, Y.K.

2013-01-01

With increasing numbers of orthopaedic devices being implanted, greater emphasis is being placed on ceramic coating technology to reduce friction and wear in mating total joint replacement components, in order to improve implant function and increase device lifespan. In this chapter, we consider ultra-hard carbon coatings, with emphasis on nanostructured diamond, as alternative bearing surfaces for metallic components. Such coatings have great potential for use in biomedical implants as a result of their extreme hardness, wear resistance, low friction and biocompatibility. These ultra-hard carbon coatings can be deposited by several techniques resulting in a wide variety of structures and properties. PMID:25285213

Superhydrophobic ceramic coatings enabled by phase-separated nanostructured composite TiO2–Cu2O thin films

International Nuclear Information System (INIS)

Aytug, Tolga; Paranthaman, Parans M; Simpson, John T; Christen, David K; Bogorin, Daniela F; Mathis, John E

2014-01-01

By exploiting phase-separation in oxide materials, we present a simple and potentially low-cost approach to create exceptional superhydrophobicity in thin-film based coatings. By selecting the TiO 2 –Cu 2 O system and depositing through magnetron sputtering onto single crystal and metal templates, we demonstrate growth of nanostructured, chemically phase-segregated composite films. These coatings, after appropriate chemical surface modification, demonstrate a robust, non-wetting Cassie–Baxter state and yield an exceptional superhydrophobic performance, with water droplet contact angles reaching to ∼172° and sliding angles <1°. As an added benefit, despite the photo-active nature of TiO 2 , the chemically coated composite film surfaces display UV stability and retain superhydrophobic attributes even after exposure to UV (275 nm) radiation for an extended period of time. The present approach could benefit a variety of outdoor applications of superhydrophobic coatings, especially for those where exposure to extreme atmospheric conditions is required. (papers)

Interfacially enhancement of PBO/epoxy composites by grafting MWCNTs onto PBO surface through melamine as molecular bridge

Science.gov (United States)

Lv, Junwei; Wang, Bin; Ma, Qi; Wang, Wenjing; Xiang, Dong; Li, Mengyao; Zeng, Lan; Li, Hui; Li, Yuntao; Zhao, Chunxia

2018-06-01

Melamine and multi-walled carbon nanotubes (MWCNTs) were grafted onto Poly-p-phenylene benzobisoxazole (PBO) fiber surface effectively via layer-by-layer method. Both of them have been chemically bonded as fourier transform infrared spectroscopy (FTIR) confirmed. Grafting melamine overcame the inertness of PBO surface. Ammoniation was processed on PBO surface through grafting melamine so that the MWCNTs could be grafted onto PBO surface. Scanning electron microscopy (SEM) images indicated that melamine used as molecular bridge could increase MWCNTs’ quantity on PBO surface. X-ray photoelectron spectroscopy (XPS) results revealed the variation of chemical composition of PBO surface. Test of interfacial shear strength (IFSS) and tensile strength indicated the great mechanical properties of modified PBO fibers when combining with epoxy resin. Furthermore, whole reaction was processed under a simple condition. Results in this research also promised a potential method to modify PBO surface.

High temperature oxidation behaviour of nanostructured cermet coatings in a mixed CO2 – O2 environment

International Nuclear Information System (INIS)

Farrokhzad, M A; Khan, T I

2014-01-01

Nanostructured ceramic-metallic (cermet) coatings composed of nanosized ceramic particles (α-Al 2 O3 and TiO 2 ) dispersed in a nickel matrix were co-electrodeposited and then oxidized at 500°C, 600°C and 700°C in a mixed gas using a Thermo-gravimetric Analysis (TGA) apparatus. The mixed gas was composed of 15% CO 2 , 10% O 2 and 75% N 2 . This research investigates the effects of CO 2 and O 2 partial pressures on time-depended oxidation rates for coatings and compared them to the results from atmospheric oxidation under similar temperatures. The increase in partial pressure of oxygen due to the presence of CO 2 at each tested temperature was calculated and correlated to the oxidation rate of the coatings. The results showed that the presence of CO 2 in the system increased the oxidation rate of cermet coatings when compared to atmospheric oxidation at the same temperature. It was also shown that the increase in the oxidation rate is not the result of CO2 acting as the primary oxidant but as a secondary oxidant which results in an increase of the total partial pressure of oxygen and consequently higher oxidation rates. The WDS and XRD analyses results showed that the presence of nanosized TiO 2 particles in a nickel matrix can improve oxidation behaviour of the coatings by formation of Ni-Ti compounds on oxidizing surface of the coating which was found beneficiary in reducing the oxidation rates for cermet coatings

Nanostructured Photocatalytic TiO2 Coating Deposited by Suspension Plasma Spraying with Different Injection Positions

Science.gov (United States)

Liu, Xuezhang; Wen, Kui; Deng, Chunming; Yang, Kun; Deng, Changguang; Liu, Min; Zhou, Kesong

2018-02-01

High plasma power is beneficial for the deposition efficiency and adhesive strength of suspension-sprayed photocatalytic TiO2 coatings, but it confronts two challenges: one is the reduced activity due to the critical phase transformation of anatase into rutile, and the other is fragmented droplets which cannot be easily injected into the plasma core. Here, TiO2 coatings were deposited at high plasma power and the position of suspension injection was varied with the guidance of numerical simulation. The simulation was based on a realistic three-dimensional time-dependent numerical model that included the inside and outside of torch regions. Scanning electron microscopy was performed to study the microstructure of the TiO2 coatings, whereas x-ray diffraction was adopted to analyze phase composition. Meanwhile, photocatalytic activities of the manufactured TiO2 coatings were evaluated by the degradation of an aqueous solution of methylene blue dye. Fragmented droplets were uniformly injected into the plasma jet, and the solidification pathway of melting particles was modified by varying the position of suspension injection. A nanostructured TiO2 coating with 93.9% anatase content was obtained at high plasma power (48.1 kW), and the adhesive coating bonding to stainless steel exhibited the desired photocatalytic activity.

Bi-doped PbO2 anodes: Electrodeposition and physico-chemical properties

International Nuclear Information System (INIS)

Shmychkova, O.; Luk’yanenko, T.; Velichenko, A.; Meda, L.; Amadelli, R.

2013-01-01

The influence of bismuth ions on kinetics of lead dioxide electrodeposition from methanesulfonate electrolytes and physico-chemical properties of obtained coatings were studied. Experimental results are consistent with a mechanism previously proposed in the literature for lead dioxide electrodeposition. The presence of bismuth ions in the electrodeposition solution causes a decrease of rate constants of lead dioxide formation due to co-adsorption phenomena. Deposits from solutions containing bismuth ions appear shiny dark grey, and show good adhesion to metal support. SEM images reveal a compact structure with spindle-shaped submicron and nanosized crystals and X-ray diffractograms demonstrated that incorporation of bismuth diminishes the size of crystal particles. Oxygen evolution was investigated to test electrocatalytic activity. It is shown, that oxygen overpotential on modified electrodes is significantly higher than on non-modified PbO 2 -electrode, which depends on bismuth content in deposit and segregation of bismuth that induces surface heterogeneity due to sites with different electroactivity for water oxidation

Passivation properties of alumina for multicrystalline silicon nanostructure prepared by spin-coating method

Science.gov (United States)

Jiang, Ye; Shen, Honglie; Yang, Wangyang; Zheng, Chaofan; Tang, Quntao; Yao, Hanyu; Raza, Adil; Li, Yufang; Huang, Chunlai

2018-02-01

In this paper, we report passivation properties of inverted pyramidal nanostructure based multi-crystalline silicon (mc-Si) by Al2O3 films with spin-coating method. Precursors AlCl3 and Al(acac)3 for Al2O3 films were chosen for comparison. Al2O3/SiO x stacks were found to be able to passivate the nanostructured surface well. With the number of spin-coating up to five, the Al2O3 films could conformally attach the nanostructure. The weighted average reflectance values (ranging from 400-900 nm) of the passivated silicon surface could be reduced to 10.74% (AlCl3) and 11.12% (Al(acac)3), and the effective carrier lifetime could reach 7.84 and 16.98 μs, respectively. This work presented a potential process to fabricate low cost high efficiency mc-Si solar cells.

Coating of biodegradable magnesium alloy bone implants using nanostructured diopside (CaMgSi{sub 2}O{sub 6})

Energy Technology Data Exchange (ETDEWEB)

Razavi, Mehdi, E-mail: mehdi.razavi@okstate.edu [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Department of Anatomical Sciences and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Savabi, Omid [Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Beni, Batoul Hashemi [Department of Anatomical Sciences and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Razavi, Seyed Mohammad [School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Vashaee, Daryoosh [School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); and others

2014-01-01

Magnesium alloys with their biodegradable characteristic can be a very good candidate to be used in orthopedic implants. However, magnesium alloys may corrode and degrade too fast for applications in the bone healing procedure. In order to enhance the corrosion resistance and the in vitro bioactivity of a magnesium alloy, a nanostructured diopside (CaMgSi{sub 2}O{sub 6}) film was coated on AZ91 magnesium alloy through combined micro-arc oxidation (MAO) and electrophoretic deposition (EPD) methods. The crystalline structures, morphologies and compositions of the coated and uncoated substrates were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy. Polarization, electrochemical impedance spectroscopy, and immersion test in simulated body fluid (SBF) were employed to evaluate the corrosion resistance and the in vitro bioactivity of the samples. The results of our investigation showed that the nanostructured diopside coating deposited on the MAO layer increases the corrosion resistance and improves the in vitro bioactivity of the biodegradable magnesium alloy.

High temperature oxidation behaviour of nanostructured cermet coatings in amixed CO/sub 2/ - O/sub 2/ environment

International Nuclear Information System (INIS)

Farrokhzad, M. A.; Khan, T. I.

2013-01-01

Nanostructured ceramic-metallic (cermet) coatings composed of nanosized ceramic particles (alpha-Al /sub 2/O/sub 3/ and TiO/sub 2/) dispersed in a nickel matrix were co-electrodeposited and then oxidized at 500 degree C, 600 degree C and 700 degree C in a mixed gas using a Thermo-gravimetric Analysis (TGA) apparatus. The mixed gas was composed of 15 percentage CO/sub 2/, 10 percentage O/sub 2/ and 75 percentage N/sub 2/. This research investigates the effects of CO/sub 2/ and O/sub 2/ partial pressures on time-depended oxidation rates for coatings and compared them to the results from atmospheric oxidation under similar temperatures. The increase in partial pressure of oxygen due to the presence of CO/sub 2/ at each tested temperature was calculated and correlated to the oxidation rate of the coatings. The results showed that the presence of CO/sub 2/ in the system increased the oxidation rate of cermet coatings when compared to atmospheric oxidation at the same temperature. It was also shown that the increase in the oxidation rate is not the result of CO/sub 2/ acting as the primary oxidant but as a secondary oxidant which results in an increase of the total partial pressure of oxygen and consequently higher oxidation rates. The WDS and XRD analyses results showed that the presence of nanosized TiO/sub 2/ particles in a nickel matrix can improve oxidation behaviour of the coatings by formation of Nu i-Tau i compounds on oxidizing surface of the coating which was found beneficiary in reducing the oxidation rates for cermet coatings. (author)

Synthesis and characterization of ZnO nanostructures on noble-metal coated substrates

Energy Technology Data Exchange (ETDEWEB)

Dikovska, A.Og. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784 (Bulgaria); Atanasova, G.B. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia (Bulgaria); Avdeev, G.V. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia (Bulgaria); Nedyalkov, N.N. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784 (Bulgaria)

2016-06-30

Highlights: • ZnO nanostructures were fabricated on Au–Ag alloy coated silicon substrates by applying pulsed laser deposition. • Morphology of the ZnO nanostructures was related to the Au–Ag alloy content in the catalyst layer. • Increasing the Ag content in Au–Ag catalyst layer changes the morphology of the ZnO nanostructures from nanorods to nanobelts. - Abstract: In this work, ZnO nanostructures were fabricated on noble-metal (Au, Ag and Au–Ag alloys) coated silicon substrates by applying pulsed laser deposition. The samples were prepared at a substrate temperature of 550 °C, an oxygen pressure of 5 Pa, and a laser fluence of 2 J cm{sup −2} – process parameters usually used for deposition of smooth and dense thin films. The metal layer's role is substantial for the preparation of nanostructures. Heating of the substrate changed the morphology of the metal layer and, subsequently, nanoparticles were formed. The use of different metal particles resulted in different morphologies and properties of the ZnO nanostructures synthesized. The morphology of the ZnO nanostructures was related to the Au–Ag alloy's content of the catalyst layer. It was found that the morphology of the ZnO nanostructures evolved from nanorods to nanobelts as the ratio of Au/Ag in the alloy catalyst was varied. The use of a small quantity of Ag in the Au–Ag catalyst (Au{sub 3}Ag) layer resulted predominantly in the deposition of ZnO nanorods. A higher Ag content in the catalyst alloy (AuAg{sub 2}) layer resulted in the growth of a dense structure of ZnO nanobelts.

Gold coated metal nanostructures grown by glancing angle deposition and pulsed electroplating

Science.gov (United States)

Grüner, Christoph; Reeck, Pascal; Jacobs, Paul-Philipp; Liedtke, Susann; Lotnyk, Andriy; Rauschenbach, Bernd

2018-05-01

Nickel based nanostructures are grown by glancing angle deposition (GLAD) on flat and pre-patterned substrates. These fabricated porous thin films were subsequently coated by pulsed electroplating with gold. The morphology and conformity of the gold coating were investigated by scanning electron microscopy and X-ray diffraction. Controlled growth of closed gold layers on the nanostructures could be achieved, while the open-pore structure of the nanosculptured thin films was preserved. Such gold coated nanostructures are a candidate for optical sensing and catalysis applications. The demonstrated method can be applied for numerous material combinations, allowing to provide GLAD thin films with new surface properties.

Electromagnetic and Microwave Absorption Properties of Carbonyl Tetrapod-Shaped Zno Nanostructures Composite Coatings

Science.gov (United States)

Yu, Haibo; Qin, Hui; Huang, Yunhua

2012-08-01

CIP/T-ZnO/EP composite coatings with carbonyl iron powders (CIP) and tetrapodshaped ZnO (T-ZnO) nanostructures as absorbers, and epoxy resin (EP) as matrix were prepared. The complex permittivity, permeability and microwave absorption properties of the coatings were investigated in the frequency range of 2-18 GHz. The effects of the weight ratio (CIP/T-ZnO/EP), the thickness and the solidification temperature on microwave absorption properties were discussed. When the weight ratio (CIP/TZnO/ EP), the thickness and the solidification temperature is 28:2:22, 1.8 mm, and 10°C, respectively, the optimal wave absorption with the minimum reflection loss (RL) value of -22.38 dB at 15.67 GHz and the bandwidth (RLcoatings may have a promising application in Ku-band (12-18 GHz).

Phase transformations of nanostructured Zr-Y-O coatings under loading

Science.gov (United States)

Fedorischeva, M. V.; Kalashnikov, M. P.; Bozhko, I. A.; Mironov, Yu. P.; Sergeev, V. P.

2017-12-01

The deposition of nanostructured Zr-Y-O/Si-Al-N-based coatings was implemented by the pulse magnetron methods. The structural-phase state of the nanostructured coatings was studied with TEM and X-ray analysis. The phase transformation in Zr-Y-O layer was observed with the X-ray diffraction analysis in the "in-situ" mode under loading in conditions of free and constrained volumes. It was found, that there were martensitic phase transformations at certain deformation levels under the conditions of the free volume and martensitic phase transformations in the local regions of the coating layer with the structure fining in constrained volume.

A study of TiB2/TiB gradient coating by laser cladding on titanium alloy

Science.gov (United States)

Lin, Yinghua; Lei, Yongping; Li, Xueqiao; Zhi, Xiaohui; Fu, Hanguang

2016-07-01

TiB2/TiB gradient coating has been fabricated by a laser cladding technique on the surface of a Ti-6Al-4V substrate using TiB2 powder as the cladding material. The microstructure and mechanical properties of the gradient coating were analyzed by SEM, EPMA, XRD, TEM and an instrument to measure hardness. With the increasing distance from the coating surface, the content of TiB2 particles gradually decreased, but the content of TiB short fibers gradually increased. Meanwhile, the micro-hardness and the elastic modulus of the TiB2/TiB coating showed a gradient decreasing trend, but the fracture toughness showed a gradient increasing trend. The fracture toughness of the TiB2/TiB coating between the center and the bottom was improved, primarily due to the debonding of TiB2 particles and the high fracture of TiB short fibers, and the fracture position of TiB short fiber can be moved to an adjacent position. However, the debonding of TiB2 particles was difficult to achieve at the surface of the TiB2/TiB coating.

Morphology-control of VO2 (B) nanostructures in hydrothermal synthesis and their field emission properties

International Nuclear Information System (INIS)

Yin Haihong; Yu Ke; Zhang Zhengli; Zhu Ziqiang

2011-01-01

VO 2 (B) nanostructures were synthesized via a facile hydrothermal process using V 2 O 5 as source material and oxalic acid as reductant. Three nanostructures of nanorods, nanocarambolas and nanobundles were found existing in the products, and a continuous changing of morphology was found in the synthesis process, during which the proportion of these three types of nanostructures can be adjusted by altering the concentrations of oxalic acid. The microstructures were evaluated using X-ray diffraction and scanning and transmission electron microscopies, respectively. FE properties measurement of these three types of nanostructures showed that the nanobundles have the best field emission performance with a turn-on field of ∼1.4 V/μm and a threshold field of ∼5.38 V/μm. These characteristics make VO 2 (B) nanostructures a competitive cathode material in field emission devices.

Effects of sintering temperature on the pyrochlore phase in PZT nanotubes and their transformation to the perovskite phase by coating with PbO multilayers.

Science.gov (United States)

Han, Jin Kyu; Choi, Yong Chan; Jeon, Do Hyen; Lee, Min Ku; Bu, Sang Don

2014-11-01

We report the phase evolution of Pb(Zr0.52Ti0.48)O3 nanotubes (PZT-NTs), from the pyrochlore to perovskite phase, with an outer diameter of about 420 nm and a wall thickness of about 10 nm. The PZT-NTs were fabricated in pores of porous anodic alumina membrane (PAM) using a spin coating of PZT sol-gel solution and subsequent annealing at 500-700 degrees C in oxygen gas. The pyrochlore phase was found to be formed at 500 degrees C, and also found not to be transformed into the perovskite phase, even though annealing was performed at higher temperatures to 700 degrees C. Elementary distribution analysis of PZT-NTs embedded in PAM reveal that Pb diffusion from nanotubes into pore walls of PAM is one of the main reasons. By employing firstly an additional PbO coating on the pyrochlore nanotubes and then subsequent annealing at 700 degrees C, we have successfully achieved an almost pure perovskite phase in nanotubes. These results suggest that PbO acts as a Pb-compensation agent in the Pb- deficient PZT-NTs. Moreover, our method can be used in the synthesis of all metal-oxide materials, including volatile elements.

Plasmonic Switches and Sensors Based on PANI-Coated Gold Nanostructures

Science.gov (United States)

Jiang, Nina

Gold nanostructures have been received intense and growing attention due to their unique properties associated with localized surface plasmon resonance (LSPR). The frequency and strength of the LSPR are highly dependent on the dielectric properties of the surrounding environment around gold nanostructures. Such dependence offers the essential basis for the achievement of plasmonic switching and sensing. While the plasmonic response of gold nanostructures is tuned by changing their dielectric environment, the external stimuli inducing the changes in the dielectric environment will be read out through the plasmonic response of gold nanostructures. As a consequence, plasmonic sensors and switches can be engineered by integrating active media that can respond to external stimuli with gold nanostructures. In this thesis research, I have achieved the coating of polyaniline (PANI) ' a conductive polymer, on gold nanostructures, and exploited the application of the core/shell nanostructures in plasmonic switching and sensing. Large modulation of the longitudinal plasmon resonance of single gold nanorods is achieved by coating PANI shell onto gold nanorods to produce colloidal plasmonic switches. The dielectric properties of PANI shell can be tuned by changing the proton-doping levels, which allows for the modulation of the plasmonic response of gold nanorods. The coated nanorods are sparsely housed in a simple microfluidic chamber. HCl and NaOH solutions are alternately pumped through the chamber for the realization of proton doping and dedoping. The plasmonic switching behavior is examined by monitoring the single-particle scattering spectra under the proton-doped and dedoped state of PANI. The coated nanorods exhibit a remarkable switching performance, with the modulation depth and scattering peak shift reaching 10 dB and 100 nm, respectively. Electrodynamic simulations are employed to confirm the plasmon switching behavior. I have further investigated the modulation of

Comparative study of the friction and wear behavior of plasma sprayed conventional and nanostructured WC-12%Co coatings on stainless steel

International Nuclear Information System (INIS)

Zhao Xiaoqin; Zhou Huidi; Chen Jianmin

2006-01-01

Conventional and nanostructured WC-12%Co coatings were deposited on 1Cr18Ni9Ti stainless steel substrate using air plasma spraying. The hardness of the coatings was measured, while their friction and wear behavior sliding against Si 3 N 4 at room temperature and elevated temperatures up to 400 deg. C was comparatively studied. The microstructures and worn surface morphologies of the coatings were comparatively analyzed as well by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDXA). It was found that the as-sprayed WC-12%Co coatings were composed of WC as the major phase and W 2 C, WC 1-x , and W 3 Co 3 C as the minor phases. The plasma sprayed nanostructured WC-12%Co coating had much higher hardness and refined microstructures than the conventional WC-12%Co coating. This largely accounted for the better wear resistance of the nanostructured WC-12%Co coating than the conventional coating. Besides, the two types of WC-12%Co coatings showed minor differences in friction coefficients, though the nanostructured WC-12%Co coating roughly had slightly smaller friction coefficient than the conventional coating under the same sliding condition. Moreover, both the conventional and nanostructured WC-12%Co coatings recorded gradually increased wear rate with increasing temperature, and the nanostructured coating was less sensitive to the temperature rise in terms of the wear resistance. The worn surfaces of the conventional WC-12%Co coating at different sliding conditions showed more severe adhesion, microfracture, and peeling as compared to the nanostructured WC-12%Co coating, which well conformed to the corresponding wear resistance of the two types of coatings. The nanostructured WC-12%Co coating with a wear rate as small as 1.01 x 10 -7 mm 3 /Nm at 400 deg. C could be promising candidate coating for the surface-modification of some sliding components subject to harsh working conditions involving elevated

Controllable synthesis and field emission enhancement of Al{sub 2}O{sub 3} coated In{sub 2}O{sub 3} core-shell nanostructures

Energy Technology Data Exchange (ETDEWEB)

Wang Yang; Li Yawei; Yu Ke; Zhu Ziqiang, E-mail: yk5188@263.net [Key Laboratory of Polar Materials and Devices (Ministry of Education of China), Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China)

2011-03-16

Four types of indium oxide (In{sub 2}O{sub 3}) nanostructures were synthesized on Au-catalysed silicon substrate via a VLS method. A rod-like In{sub 2}O{sub 3} nanostructure was chosen to fabricate In{sub 2}O{sub 3}-Al{sub 2}O{sub 3} core-shell nanostructures with different shell thicknesses via a two-step method. Core-shell nanostructures with shell thickness of 30 nm are reprocessed by annealing and H{sub 2} plasma treating. Field emission (FE) properties of all the samples were measured and compared. It is found that Al{sub 2}O{sub 3} coatings remarkably decrease the effective work function and improve the FE capabilities of In{sub 2}O{sub 3} nanostructures (turn-on field decreases from 1.34 to 1.26 V {mu}m{sup -1}, threshold field decreases from 3.60 to 2.64 V {mu}m{sup -1}). Annealing and H{sub 2} plasma treating can promote the improvement even further (turn-on field 1.23 V {mu}m{sup -1}, 1.21 V {mu}m{sup -1} and threshold field 2.50 V {mu}m{sup -1}, 2.14 V {mu}m{sup -1}, respectively). The FE enhancement is attributed to the electron accumulation in the insulating Al{sub 2}O{sub 3} nanostructure and the electron redistribution at the heterojunction.

Development of Cr{sub 3}C{sub 2}-25(Ni20Cr) nanostructured coatings; Desenvolvimento de revestimentos nanostruturados de Cr{sub 3}C{sub 2}-25(Ni20Cr)

Energy Technology Data Exchange (ETDEWEB)

Cunha, Cecilio Alvares da

2012-07-01

This study is divided in two parts. The first part is about the preparation of nanostructured Cr{sub 3}C{sub 2}-25(Ni20Cr) powders by high energy milling followed by characterization of the milled and the as received powder. Analyses of some of the data obtained were done using a theoretical approach. The second part of this study is about the preparation and characterization of coatings prepared with the nanostructured as well as the as received Cr{sub 3}C{sub 2}-25(Ni20Cr) powders. The high temperature erosion-oxidation (E-O) behavior of the coatings prepared with the two types of powders has been compared based on a technological approach. The average crystallite size of the Cr{sub 3}C{sub 2}-25(Ni20Cr) powder decreased rapidly from 145 nm to 50 nm in the initial stages of milling and thereafter decreased slowly to a steady state value of around 10 nm with further increase in milling time. This steady state corresponds to the beginning of a dynamic recovery process. The maximum lattice strain ({epsilon} = 1,17%) was observed in powders milled for 16 hours, and this powders critical crystallite size was 28 nm. In contrast, the lattice parameter attained a minimum for powders milled for 16 hours. Upon reaching the critical crystallite size, the dislocation density attained a steady state regime and all plastic deformation introduced in the material there after was in the form of events occurring at the grain boundaries, due mainly to grain boundary sliding. The deformation energy stored in the crystal lattice of the Cr{sub 3}C{sub 2}-25(Ni20Cr) powders milled for different times was determined from enthalpy variation measurements. These results indicated that the maximum enthalpy variation ({delta}H = 722 mcal) also occurred for powders milled for 16 hours. In a similar manner, the maximum specific heat variation ({delta}C{sub p} = 0,278 cal/gK) occurred for powders milled for 16 hours. The following mechanical properties of Cr{sub 3}C{sub 2}-25(Ni20Cr) coatings

OXIDACIÓN ELECTROQUÍMICA DE LAMBDACIALOTRINA SOBRE ELECTRODOS DE PBO2-BI

Directory of Open Access Journals (Sweden)

Leonardo Cifuentes

2015-09-01

Full Text Available The electrochemical oxidation of lambdacyhalotrin in a triton X-100 water solution on a PbO2-Bi electrode has been studied. It was discovered that electrocatalytic degradation proceeded through the Langmuir-Hinshelwood (L-H mechanism. The Langmuir adsorption equilibrium constant of the organic compound on the PbO2-Bi surface (0.67 (±0.02 mg-1L and the L-H maximum reaction rate for lambdacyhalotrin oxidation (0.040 (±0.002 mg L-1 min-1 was also determined on the basis of kinetic data. Oxidation/mineralization was tested at electrode potential higher than 2.3 V vs. Ag/AgCl, in this conditions the higher degradation percent of 85 (±4 % has been obtained.

ELABORATION OF AN EPOXY COATING REINFORCED WITH ZIRCONIUM CARBIDE NANOSTRUCTURES

Directory of Open Access Journals (Sweden)

Lucia G. Díaz-Barriga

2013-12-01

Full Text Available This work shows the preparation of a transparent epoxy coating reinforced with 200 PPM of zirconium carbide nanostructures. The nanostructures of ZrC were prepared by mechanosynthesis. The additive characteristics analyzed by X-ray diffraction (XRD and scanning electron microscopy (SEM were presented. Epoxy coating adhesion on a steel plate was analyzed using MEB. Thermogravimetric analysis (TGA was performed to the reinforced paints between 20-700 °C. The reinforced enamel was compared with an enamel without nanostructures. There is not vaporization of reinforced enamel at a 95 y 100 °C with ZrC particles size of 10 µm y 120 nm respectively. The final enamel degradation is slower when there is a 14% by weight of the residue and 426 °C with 120nm diameter particles.

Composition and Performance of Nanostructured Zirconium Titanium Conversion Coating on Aluminum-Magnesium Alloys

Directory of Open Access Journals (Sweden)

Sheng-xue Yu

2013-01-01

Full Text Available Nanostructured conversion coating of Al-Mg alloy was obtained via the surface treatment with zirconium titanium salt solution at 25°C for 10 min. The zirconium titanium salt solution is composed of tannic acid 1.00 g·L−1, K2ZrF6 0.75 g·L−1, NaF 1.25 g·L−1, MgSO4 1.0 g/L, and tetra-n-butyl titanate (TBT 0.08 g·L−1. X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, and Fourier transform infrared spectrum (FT-IR were used to characterize the composition and structure of the obtained conversion coating. The morphology of the conversion coating was obtained by atomic force microscopy (AFM and scanning electron microscopy (SEM. Results exhibit that the zirconium titanium salt conversion coating of Al-Mg alloy contains Ti, Zr, Al, F, O, Mg, C, Na, and so on. The conversion coating with nm level thickness is smooth, uniform, and compact. Corrosion resistance of conversion coating was evaluated in the 3.5 wt.% NaCl electrolyte through polarization curves and electrochemical impedance spectrum (EIS. Self-corrosion current density on the nanostructured conversion coating of Al-Mg alloy is 9.7×10-8A·cm-2, which is only 2% of that on the untreated aluminum-magnesium alloy. This result indicates that the corrosion resistance of the conversion coating is improved markedly after chemical conversion treatment.

Hierarchical adaptive nanostructured PVD coatings for extreme tribological applications: the quest for nonequilibrium states and emergent behavior

Directory of Open Access Journals (Sweden)

German S Fox-Rabinovich, Kenji Yamamoto, Ben D Beake, Iosif S Gershman, Anatoly I Kovalev, Stephen C Veldhuis, Myram H Aguirre, Goulnara Dosbaeva and Jose L Endrino

2012-01-01

Full Text Available Adaptive wear-resistant coatings produced by physical vapor deposition (PVD are a relatively new generation of coatings which are attracting attention in the development of nanostructured materials for extreme tribological applications. An excellent example of such extreme operating conditions is high performance machining of hard-to-cut materials. The adaptive characteristics of such coatings develop fully during interaction with the severe environment. Modern adaptive coatings could be regarded as hierarchical surface-engineered nanostructural materials. They exhibit dynamic hierarchy on two major structural scales: (a nanoscale surface layers of protective tribofilms generated during friction and (b an underlying nano/microscaled layer. The tribofilms are responsible for some critical nanoscale effects that strongly impact the wear resistance of adaptive coatings. A new direction in nanomaterial research is discussed: compositional and microstructural optimization of the dynamically regenerating nanoscaled tribofilms on the surface of the adaptive coatings during friction. In this review we demonstrate the correlation between the microstructure, physical, chemical and micromechanical properties of hard coatings in their dynamic interaction (adaptation with environment and the involvement of complex natural processes associated with self-organization during friction. Major physical, chemical and mechanical characteristics of the adaptive coating, which play a significant role in its operating properties, such as enhanced mass transfer, and the ability of the layer to provide dissipation and accumulation of frictional energy during operation are presented as well. Strategies for adaptive nanostructural coating design that enhance beneficial natural processes are outlined. The coatings exhibit emergent behavior during operation when their improved features work as a whole. In this way, as higher-ordered systems, they achieve multifunctionality

Hierarchical adaptive nanostructured PVD coatings for extreme tribological applications: the quest for nonequilibrium states and emergent behavior.

Science.gov (United States)

Fox-Rabinovich, German S; Yamamoto, Kenji; Beake, Ben D; Gershman, Iosif S; Kovalev, Anatoly I; Veldhuis, Stephen C; Aguirre, Myriam H; Dosbaeva, Goulnara; Endrino, Jose L

2012-08-01

Adaptive wear-resistant coatings produced by physical vapor deposition (PVD) are a relatively new generation of coatings which are attracting attention in the development of nanostructured materials for extreme tribological applications. An excellent example of such extreme operating conditions is high performance machining of hard-to-cut materials. The adaptive characteristics of such coatings develop fully during interaction with the severe environment. Modern adaptive coatings could be regarded as hierarchical surface-engineered nanostructural materials. They exhibit dynamic hierarchy on two major structural scales: (a) nanoscale surface layers of protective tribofilms generated during friction and (b) an underlying nano/microscaled layer. The tribofilms are responsible for some critical nanoscale effects that strongly impact the wear resistance of adaptive coatings. A new direction in nanomaterial research is discussed: compositional and microstructural optimization of the dynamically regenerating nanoscaled tribofilms on the surface of the adaptive coatings during friction. In this review we demonstrate the correlation between the microstructure, physical, chemical and micromechanical properties of hard coatings in their dynamic interaction (adaptation) with environment and the involvement of complex natural processes associated with self-organization during friction. Major physical, chemical and mechanical characteristics of the adaptive coating, which play a significant role in its operating properties, such as enhanced mass transfer, and the ability of the layer to provide dissipation and accumulation of frictional energy during operation are presented as well. Strategies for adaptive nanostructural coating design that enhance beneficial natural processes are outlined. The coatings exhibit emergent behavior during operation when their improved features work as a whole. In this way, as higher-ordered systems, they achieve multifunctionality and high wear

Comparative study of silicate glasses containing Bi2O3, PbO and BaO: Radiation shielding and optical properties

International Nuclear Information System (INIS)

Kirdsiri, K.; Kaewkhao, J.; Chanthima, N.; Limsuwan, P.

2011-01-01

Research highlights: → We change Bi 2 O 3 , PbO and BaO concentration in silicate glasses. → The densities of Bi 2 O 3 glasses more than PbO glasses and BaO glasses. → The Um of Bi 2 O 3 glasses and PbO glasses are comparable and more than BaO glasses. → This suggests that Bi 2 O 3 can replace PbO in radiation shielding glasses. - Abstract: The radiation shielding and optical properties of xBi 2 O 3 :(100-x)SiO 2 , xPbO:(100-x)SiO 2 and xBaO:(100-x)SiO 2 glass systems (where 30 ≤ x ≤ 70 is the composition by weight%) have been investigated. Total mass attenuation coefficients (μ m ) of glasses at 662 keV were improved by increasing their Bi 2 O 3 and PbO content, which raised the photoelectric absorption in glass matrices. Raising the BaO content to the same fraction range, however, brought no significant change to μ m . These results indicate that photon is strongly attenuated in Bi 2 O 3 and PbO containing glasses, and but not in BaO containing glass. The results from the optical absorption spectra show an edge that was not sharply defined; clearly indicating the amorphous nature of glass samples. It is observed that the cutoff wavelength for Bi 2 O 3 containing glass was longer than PbO and BaO containing glasses.

Effects of TiB2 Particle and Short Fiber Sizes on the Microstructure and Properties of TiB2-Reinforced Composite Coatings

Science.gov (United States)

Lin, Yinghua; Yao, Jianhua; Wang, Liang; Zhang, Qunli; Li, Xueqiao; Lei, Yongping; Fu, Hanguang

2018-03-01

In this study, particle and short fiber-reinforced titanium matrix composite coatings are prepared via laser in situ technique using (0.5 and 50 μm) TiB2 and Ti powder as cladding materials. The microstructure and properties of the composite coatings are studied, and the changing mechanism of the microstructure is discussed. The results reveal that particle agglomeration is prone to appear with using fine TiB2 particles. Decomposition of the particles preferentially occurs with using coarse TiB2 particles. The cracks and pores on the surface of the coating are formed at a lower laser energy density. With the increase in the laser energy density, cracking on the surface of the coating diminishes, but the coating exhibits depression behavior. The depression extent of the coating using fine TiB2 particle as the reinforcement is much less than that of the coating using coarse TiB2 particle. Moreover, the size of the aggregate and the tendency of cracking can be reduced with the increase in Ti addition. Meanwhile, short TiB fiber bundles are formed by the diffusion mechanism of rod aggregate, and randomly oriented TiB short fibers are formed mainly by the dissolution-precipitation mechanism of fine TiB2 particles. Moreover, the growth of short TiB fibers can be in an alternating manner between B27 and Bf structures. The micro-hardness and wear resistance of the coatings are evidently higher than that of the titanium alloy substrate. The wear resistance of the large size TiB2 coating is higher than that of the small size TiB2 coating under the condition of low load.

Microstructure and properties of TiB2-TiB reinforced titanium matrix composite coating by laser cladding

Science.gov (United States)

Lin, Yinghua; Yao, Jianhua; Lei, Yongping; Fu, Hanguang; Wang, Liang

2016-11-01

TiB2 particle and TiB short fiber reinforced titanium matrix composite coatings were prepared utilizing in situ synthesized technique by laser cladding on the surface of Ti6Al4V alloy. Through the experiment, it was found that the surface of the single-track coatings appeared in the depression, but it can be improved by laser track overlapping. With the increase of laser power density, the amount of TiB short fiber was increased, and the distribution of TiB2 and TiB became more uniform from the top to bottom. The micro-hardness of TiB2/TiB coating showed a gradient decreasing trend, and the average micro-hardness of the coatings was two-fold higher than that of the substrate. Due to the strengthening effect of TiB2 particle and TiB short fiber, the wear volume loss of the center of the coating was approximately 30% less than that of the Ti-6Al-4V substrate, and the wear mechanism of the coating was mild fatigue particle detachment.

Tribological Properties of HVOF-Sprayed TiB2-NiCr Coatings with Agglomerated Feedstocks

Science.gov (United States)

Zhao, Zichun; Li, Hui; Yang, Tianlong; Zhu, Hongbin

2018-04-01

Boride materials have drawn great attention in surface engineering field, owing to their high hardness and good wear resistance. In our previous work, a plasma-sprayed TiB2-based cermet coating was deposited, but the coating toughness was significantly influenced by the formation of a brittle ternary phase (Ni20Ti3B6) derived from the reaction between TiB2 and metal binder. In order to suppress such a reaction occurred in the high-temperature spraying process, the high-velocity oxygen-fuel spraying technique was applied to prepare the TiB2-NiCr coating. Emphasis was paid on the microstructure, the mechanical properties, and the sliding wearing performance of the coating. The result showed that the HVOF-sprayed coating mainly consisted of hard ceramic particles including TiB2, CrB, and the binder phase. No evidence of Ni20Ti3B6 phase was found in the coating. The mechanical properties of HVOF-sprayed TiB2-NiCr coating were comparable to the conventional Cr3C2-NiCr coating. The frictional coefficient of the TiB2-NiCr coating was lower than the Cr3C2-NiCr coating when sliding against a bearing steel ball.

Tribological Properties of HVOF-Sprayed TiB2-NiCr Coatings with Agglomerated Feedstocks

Science.gov (United States)

Zhao, Zichun; Li, Hui; Yang, Tianlong; Zhu, Hongbin

2018-03-01

Boride materials have drawn great attention in surface engineering field, owing to their high hardness and good wear resistance. In our previous work, a plasma-sprayed TiB2-based cermet coating was deposited, but the coating toughness was significantly influenced by the formation of a brittle ternary phase (Ni20Ti3B6) derived from the reaction between TiB2 and metal binder. In order to suppress such a reaction occurred in the high-temperature spraying process, the high-velocity oxygen-fuel spraying technique was applied to prepare the TiB2-NiCr coating. Emphasis was paid on the microstructure, the mechanical properties, and the sliding wearing performance of the coating. The result showed that the HVOF-sprayed coating mainly consisted of hard ceramic particles including TiB2, CrB, and the binder phase. No evidence of Ni20Ti3B6 phase was found in the coating. The mechanical properties of HVOF-sprayed TiB2-NiCr coating were comparable to the conventional Cr3C2-NiCr coating. The frictional coefficient of the TiB2-NiCr coating was lower than the Cr3C2-NiCr coating when sliding against a bearing steel ball.

Bactericidal Effects of HVOF-Sprayed Nanostructured TiO2 on Pseudomonas aeruginosa

Science.gov (United States)

Jeffery, B.; Peppler, M.; Lima, R. S.; McDonald, A.

2010-01-01

Titanium dioxide (TiO2) has been shown to exhibit photocatalytic bactericidal activity. This preliminary study focused on examining the photocatalytic activity of high-velocity oxy-fuel (HVOF) sprayed nanostructured TiO2 coatings to kill Pseudomonas aeruginosa. The surfaces of the nanostructured TiO2 coatings were lightly polished before addition of the bacterial solution. Plates of P. aeruginosa were grown, and then suspended in a phosphate buffer saline (PBS) solution. The concentration of bacteria used was determined by a photo-spectrometer, which measured the amount of light absorbed by the bacteria-filled solution. This solution was diluted and pipetted onto the coating, which was exposed to white light in 30-min intervals, up to 120 min. It was found that on polished HVOF-sprayed coatings exposed to white light, 24% of the bacteria were killed after exposure for 120 min. On stainless steel controls, approximately 6% of the bacteria were not recovered. These preliminary results show that thermal-sprayed nanostructured TiO2 coatings exhibited photocatalytic bactericidal activity with P. aeruginosa.

Detection of gain enhancement in laser-induced fluorescence of rhodamine B lasing dye by silicon dioxide nanostructures-coated cavity

Science.gov (United States)

Al-Tameemi, Mohammed N. A.

2018-03-01

In this work, nanostructured silicon dioxide films are deposited by closed-field unbalanced direct-current (DC) reactive magnetron sputtering technique on two sides of quartz cells containing rhodamine B dye dissolved in ethanol with 10‒5 M concentration as a random gain medium. The preparation conditions are optimized to prepare highly pure SiO2 nanostructures with a minimum particle size of about 20 nm. The effect of SiO2 films as external cavity for the random gain medium is determined by the laser-induced fluorescence of this medium, and an increase of about 200% in intensity is observed after the deposition of nanostructured SiO2 thin films on two sides of the dye cell.

Nano-structured yttria-stabilized zirconia coating by electrophoretic deposition

Energy Technology Data Exchange (ETDEWEB)

Maleki-Ghaleh, H., E-mail: H_Maleki@sut.ac.ir [Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Rekabeslami, M. [Faculty of Mechanical Engineering, Materials Science and Engineering Division, K. N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Shakeri, M.S. [Materials and Energy Research Center, Karaj (Iran, Islamic Republic of); Siadati, M.H. [Faculty of Mechanical Engineering, Materials Science and Engineering Division, K. N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Javidi, M. [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of); Talebian, S.H. [Faculty of Petroleum Engineering, Universiti Technologi Petronas, Perak (Malaysia); Aghajani, H. [Department of Materials Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of)

2013-09-01

The most important role of thermal barrier coatings is to reduce the temperature of the substrate in high temperature applications. Nanoparticle zirconia might be a suitable choice for improving the efficiency of thermal barrier coatings. Nanostructured coatings have lower thermal conduction, higher thermal expansion and lower dimensional variations at higher temperatures in comparison with the microstructured coatings. Electrophoretic deposition has been preferred for thermal barrier coatings due to its simplicity, controllability and low cost. In the present study, three different suspensions of ZrO{sub 2}–8 wt%Y{sub 2}O{sub 3} (40 nm) made with ethanol, acetone and acetyl acetone were used. Electrophoretic deposition was conducted at a fixed voltage of 60 V for 120 s on aluminized Inconel 738-LC, and then heat treated at 1100{sup o}C for 4 h in air atmosphere. The coating morphology and elemental distribution were studied using scanning electron microscopy. It was observed that suspension media have an important effect on the quality of the final product. Acetyl acetone showed better dispersion of particles than the other two media. Consequently, deposition from acetyl acetone resulted in uniform and crack-free layers while those from ethanol and acetone were completely non-uniform due to agglomeration and low viscosity, respectively.

The poisoning effect of PbO on Mn-Ce/TiO{sub 2} catalyst for selective catalytic reduction of NO with NH{sub 3} at low temperature

Energy Technology Data Exchange (ETDEWEB)

Zhou, Lingling [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Li, Caiting, E-mail: ctli@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Zhao, Lingkui; Zeng, Guangming; Gao, Lei; Wang, Yan; Yu, Ming’e [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China)

2016-12-15

Highlights: • The poisoning effects of PbO-doped Mn-Ce/TiO{sub 2} catalysts for low temperature NH{sub 3}-SCR were investigated. • Low concentration of Mn{sup 4+} and chemisorbed oxygen (O{sub b}) were not favorable for the generation of intermediates. • The decreased Ce{sup 3+} and less reducible of manganese oxides hindered the redox cycle (Mn{sup 3+} + Ce{sup 4+} ↔ Mn{sup 4+} + Ce{sup 3+}). • The doping of PbO not only altered acid sites but also inhibited ammonia adsorption as well as activation. • The poisoning of PbO resulted in the decrease of ad-NO{sub x} species (only a spot of bidentate nitrates remained). - Abstract: Lead oxide (PbO) as one of the typical heavy metals in flue gas from power plants has strong accumulation as well as poisoning effects on SCR catalysts. In this paper, a series of PbO-doped Mn-Ce/TiO{sub 2} catalysts were synthesized by impregnation method. The poisoning effects of PbO over Mn-Ce/TiO{sub 2} samples for selective catalytic reduction of NO by NH{sub 3} were investigated based on catalytic activity test and characterizations. The NO conversion of Mn-Ce/TiO{sub 2} was greatly decreased after the addition of PbO. It was obvious that the NO conversion efficiency of Mn-Ce/TiO{sub 2} catalyst declined from 96.75% to about 40% at 200 °C when Pb:Mn molar ratio reached 0.5. Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Hydrogen temperature programmed reduction (H{sub 2}-TPR), Ammonia temperature programmed desorption (NH{sub 3}-TPD) and Fourier transform infrared spectroscopy (FT-IR) were carried out to study the deactivation reasons of PbO poisoned catalysts. Manganese oxides’ crystallization, less reducible of manganese and cerium oxides, the decreasing of surface area, Mn{sup 4+} as well as Ce{sup 3+} concentration and chemisorbed oxygen (O{sub b}) after the introduction of PbO, all of these resulted in a poor SCR performance

Electrochemical disinfection of simulated ballast water on PbO2/graphite felt electrode

International Nuclear Information System (INIS)

Chen, Shuiping; Hu, Weidong; Hong, Jianxun; Sandoe, Steve

2016-01-01

A novel PbO 2 /graphite felt electrode was constructed by electrochemical deposition of PbO 2 on graphite felt and characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) analysis. The prepared electrode is a viable technology for inactivation of Escherichia coli, Enterococcus faecalis, and Artemia salina as indicator organisms in simulated ballast water treatment, which meets the International Maritime Organization (IMO) Regulation D-2. The effects of contact time and current density on inactivation were investigated. An increase in current density generally had a beneficial effect on the inactivation of the three species. E.faecalis and A.salina were more resistant to electrochemical disinfection than E. coli. The complete disinfection of E.coli was achieved in <8 min at an applied current density of 253 A/m 2 . Complete inactivation of E. faecalis and A.salina was achieved at the same current density after 60 and 40 min of contact time, respectively. A. salina inactivation follows first-order kinetics. - Highlights: •A novel PbO 2 /graphite felt anode was developed for the electrochemical treatment of the simulated ballast water. •The technology meets the IMO D‐2 regulation and provides a high degree of removal of the microorganisms of ballast water without any additional chemical substances. •E.faecalis, E.coli, and A.salina cells in simulated ballast water were completely inactivated after 60, 8 and 40 min of contact time at 253 A/m 2 of current density, respectively.

Flower-like hydrogenated TiO2(B) nanostructures as anode materials for high-performance lithium ion batteries

Science.gov (United States)

Zhang, Zhonghua; Zhou, Zhenfang; Nie, Sen; Wang, Honghu; Peng, Hongrui; Li, Guicun; Chen, Kezheng

2014-12-01

Flower-like hydrogenated TiO2(B) nanostructures have been synthesized via a facile solvothermal approach combined with hydrogenation treatment. The obtained TiO2(B) nanostructures show uniform and hierarchical flower-like morphology with a diameter of 124 ± 5 nm, which are further constructed by primary nanosheets with a thickness of 10 ± 1.2 nm. The Ti3+ species and/or oxygen vacancies are well introduced into the structures of TiO2(B) after hydrogen reduction, resulting in an enhancement in the electronic conductivity (up to 2.79 × 10-3 S cm-1) and the modified surface electrochemical activity. When evaluated for lithium storage capacity, the hydrogenated TiO2(B) nanostructures exhibit enhanced electrochemical energy storage performances compared to the pristine TiO2(B) nanostructures, including high capacity (292.3 mA h g-1 at 0.5C), excellent rate capability (179.6 mA h g-1 at 10C), and good cyclic stability (98.4% capacity retention after 200 cycles at 10C). The reasons for these improvements are explored in terms of the increased electronic conductivity and the facilitation of lithium ion transport arising from the introduction of oxygen vacancies and the unique flower-like morphologies.

In vitro study of nanostructured diopside coating on Mg alloy orthopedic implants

International Nuclear Information System (INIS)

Razavi, Mehdi; Fathi, Mohammadhossein; Savabi, Omid; Vashaee, Daryoosh; Tayebi, Lobat

2014-01-01

The high corrosion rate of Mg alloys has hindered their application in various areas, particularly for orthopedic applications. In order to decrease the corrosion rate and to improve the bioactivity, mechanical stability and cytocompatibility of the Mg alloy, nanostructured diopside (CaMgSi 2 O 6 ) has been coated on AZ91 Mg alloy using a combined micro arc oxidation (MAO) and electrophoretic deposition (EPD) method. The crystalline structure, the morphology and the composition of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical corrosion test, immersion test, and compression test were used to evaluate the corrosion resistance, the in vitro bioactivity and the mechanical stability of the samples, respectively. The cytocompatibility of the samples was tested by the cell viability and the cell attachment of L-929 cells. The results confirmed that the diopside coating not only slows down the corrosion rate, but also enhances the in vitro bioactivity, mechanical stability and cytocompatibility of AZ91 Mg alloy. Therefore, Mg alloy coated with nanostructured diopside offers a promising approach for biodegradable bone implants. - Highlights: • The diopside coating was applied on Mg alloy using the combined MAO and EPD methods. • The corrosion resistance of the diopside coated Mg alloy was noticeably improved. • The in vitro bioactivity of the diopside coated Mg alloy was considerably increased. • The mechanical stability of biodegradable Mg alloy was enhanced by diopside coating. • The cytocompatibility of the Mg alloy was improved employing diopside coating

In vitro study of nanostructured diopside coating on Mg alloy orthopedic implants

Energy Technology Data Exchange (ETDEWEB)

Razavi, Mehdi, E-mail: mehdi.razavi@okstate.edu [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Savabi, Omid [Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Vashaee, Daryoosh [School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Tayebi, Lobat, E-mail: lobat.tayebi@okstate.edu [School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078 (United States)

2014-08-01

The high corrosion rate of Mg alloys has hindered their application in various areas, particularly for orthopedic applications. In order to decrease the corrosion rate and to improve the bioactivity, mechanical stability and cytocompatibility of the Mg alloy, nanostructured diopside (CaMgSi{sub 2}O{sub 6}) has been coated on AZ91 Mg alloy using a combined micro arc oxidation (MAO) and electrophoretic deposition (EPD) method. The crystalline structure, the morphology and the composition of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical corrosion test, immersion test, and compression test were used to evaluate the corrosion resistance, the in vitro bioactivity and the mechanical stability of the samples, respectively. The cytocompatibility of the samples was tested by the cell viability and the cell attachment of L-929 cells. The results confirmed that the diopside coating not only slows down the corrosion rate, but also enhances the in vitro bioactivity, mechanical stability and cytocompatibility of AZ91 Mg alloy. Therefore, Mg alloy coated with nanostructured diopside offers a promising approach for biodegradable bone implants. - Highlights: • The diopside coating was applied on Mg alloy using the combined MAO and EPD methods. • The corrosion resistance of the diopside coated Mg alloy was noticeably improved. • The in vitro bioactivity of the diopside coated Mg alloy was considerably increased. • The mechanical stability of biodegradable Mg alloy was enhanced by diopside coating. • The cytocompatibility of the Mg alloy was improved employing diopside coating.

Nanostructured Si-substituted hydroxyapatite coatings for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Rau, Julietta V., E-mail: giulietta.rau@ism.cnr.it [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133 Rome (Italy); Fosca, Marco [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, 100-00133 Rome (Italy); Cacciotti, Ilaria [Università di Roma “Tor Vergata”, Dipartimento di Ingegneria Industriale,UR INSTM “Roma Tor Vergata”, Via del Politecnico, 1-00133 Rome (Italy); Laureti, Sara [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via Salaria km 29.300-00016 Monterotondo Scalo (RM) (Italy); Bianco, Alessandra [Università di Roma “Tor Vergata”, Dipartimento di Ingegneria Industriale,UR INSTM “Roma Tor Vergata”, Via del Politecnico, 1-00133 Rome (Italy); Teghil, Roberto [Università della Basilicata, Dipartimento di Scienze, Via dell' Ateneo Lucano 10-85100, Potenza (Italy)

2013-09-30

In the present work, the Si-HAp coatings were deposited on titanium substrates by Pulsed Laser Deposition technique. For deposition, the Si-HAp targets (1.4 wt.% of Si), produced starting from wet synthesized powders, were used. The properties of coatings were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy and Vickers microhardness. The obtained Si-HAp coatings presented a nanosized structure, proper thickness and hardness for applications in orthopedical and dental surgery, aimed at improving the stability and the osteointegration of bone implants. - Highlights: ► Pulsed Laser Deposition method was applied to coat heated Titanium supports. ► Films were deposited using a target of Silicon-Hydroxyapatite sintered ceramics. ► Nanostructured crystalline hard film was grown replicating target composition. ► Prepared coating could be used for orthopedic and dental implants applications.

Nanostructured Si-substituted hydroxyapatite coatings for biomedical applications

International Nuclear Information System (INIS)

Rau, Julietta V.; Fosca, Marco; Cacciotti, Ilaria; Laureti, Sara; Bianco, Alessandra; Teghil, Roberto

2013-01-01

In the present work, the Si-HAp coatings were deposited on titanium substrates by Pulsed Laser Deposition technique. For deposition, the Si-HAp targets (1.4 wt.% of Si), produced starting from wet synthesized powders, were used. The properties of coatings were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy and Vickers microhardness. The obtained Si-HAp coatings presented a nanosized structure, proper thickness and hardness for applications in orthopedical and dental surgery, aimed at improving the stability and the osteointegration of bone implants. - Highlights: ► Pulsed Laser Deposition method was applied to coat heated Titanium supports. ► Films were deposited using a target of Silicon-Hydroxyapatite sintered ceramics. ► Nanostructured crystalline hard film was grown replicating target composition. ► Prepared coating could be used for orthopedic and dental implants applications

Preparation and characterization of dutasteride-loaded nanostructured lipid carriers coated with stearic acid-chitosan oligomer for topical delivery.

Science.gov (United States)

Noor, Norhayati Mohamed; Sheikh, Khalid; Somavarapu, Satyanarayana; Taylor, Kevin M G

2017-08-01

Dutasteride, used for treating benign prostate hyperplasia (BPH), promotes hair growth. To enhance delivery to the hair follicles and reduce systemic effects, in this study dutasteride has been formulated for topical application, in a nanostructured lipid carrier (NLC) coated with chitosan oligomer-stearic acid (CSO-SA). CSO-SA has been successfully synthesized, as confirmed using 1 H NMR and FTIR. Formulation of dutasteride-loaded nanostructured lipid carriers (DST-NLCs) was optimized using a 2 3 full factorial design. This formulation was coated with different concentrations of stearic acid-chitosan solution. Coating DST-NLCs with 5% SA-CSO increased mean size from 187.6±7.0nm to 220.1±11.9nm, and modified surface charge, with zeta potentials being -18.3±0.9mV and +25.8±1.1mV for uncoated and coated DST-NLCs respectively. Transmission electron microscopy showed all formulations comprised approximately spherical particles. DST-NLCs, coated and uncoated with CSO-SA, exhibited particle size stability over 60days, when stored at 4-8°C. However, NLCs coated with CSO (without conjugation) showed aggregation when stored at 4-8°C after 30days. The measured particle size for all formulations stored at 25°C suggested aggregation, which was greatest for DST-NLCs coated with 10% CSO-SA and 5% CSO. All nanoparticle formulations exhibited rapid release in an in vitro release study, with uncoated NLCs exhibiting the fastest release rate. Using a Franz diffusion cell, no dutasteride permeated through pig ear skin after 48h, such that it was not detected in the receptor chamber for all samples. The amount of dutasteride in the skin was significantly different (pchitosan conjugate was successfully prepared, and modified the surface charge of DST-NLCs from negative to positive. These stable, less cytotoxic, positively-charged dutasteride-loaded nanostructured lipid carriers, with stearic acid-chitosan oligomer conjugate, are appropriate for topical delivery and have

Nanostructure transition in Cr–C–N coatings deposited by pulsed closed field unbalanced magnetron sputtering

International Nuclear Information System (INIS)

Wu, Z.L.; Lin, J.; Moore, J.J.; Lei, M.K.

2012-01-01

Cr–C–N coatings with different compositions, i.e. (C + N)/Cr atomic ratios (x) of 0.81–2.77, were deposited using pulsed closed field unbalanced magnetron sputtering by varying the chromium and graphite target powers, the pulse configuration and the ratio of the nitrogen flow rate to the total gas flow rate. Three kinds of nanostructures were identified in the Cr–C–N coatings dependent on the x values: a nano-columnar structure of hexagonal closed-packed (hcp) Cr 2 (C,N) and face-centered cubic (fcc) Cr(C,N) at x = 0.81 and 1.03 respectively, a nanocomposite structure consisting of nanocrystalline Cr(C,N) embedded in an amorphous C(N) matrix at x = 1.26 and 1.78, and a Cr-containing amorphous C(N) structure at x = 2.77. A maximum hardness of 31.0 GPa and a high H/E ratio of 1.0 have been achieved in the nc-Cr(C,N)/a-C(N) nanocomposite structure at x = 1.26, whereas the coating with a Cr-containing amorphous C(N) structure had a minimum hardness of 10.9 GPa and a low H/E ratio of 0.08 at x = 2.77. The incorporation of carbon into the Cr–N coatings led to a phase transition from hcp-Cr 2 (C,N) to fcc-Cr(C,N) by the dissolution into the nanocrystallites, and promoted the amorphization of Cr–C–N coatings with the precipitation of amorphous C(N). It was found that a high x value over 1.0 in the Cr–C–N coatings is the composition threshold to the nanostructure transition. - Highlights: ► Nanostructure transition of Cr–C–N coatings depended on (C + N)/Cr atomic ratio. ► A nano-columnar structure formed at atomic ratio less than 1.0. ► A nc-Cr(C,N)/a-C(N) nanocomposite structure formed at atomic ratio of 1.0–2.7. ► A Cr-containing amorphous C(N) structure formed at atomic ratio more than 2.7. ► Maximum hardness of 31.0 GPa was for nanocomposite coatings at atomic ratio of 1.26.

Electrodes synthesized from carbon nanostructures coated with a smooth and conformal metal adlayer

Science.gov (United States)

Adzic, Radoslav; Harris, Alexander

2014-04-15

High-surface-area carbon nanostructures coated with a smooth and conformal submonolayer-to-multilayer thin metal films and their method of manufacture are described. The preferred manufacturing process involves the initial oxidation of the carbon nanostructures followed by a surface preparation process involving immersion in a solution with the desired pH to create negative surface dipoles. The nanostructures are subsequently immersed in an alkaline solution containing a suitable quantity of non-noble metal ions which adsorb at surface reaction sites. The metal ions are then reduced via chemical or electrical means. The nanostructures are exposed to a solution containing a salt of one or more noble metals which replace adsorbed non-noble surface metal atoms by galvanic displacement. The process can be controlled and repeated to obtain a desired film coverage. The resulting coated nanostructures may be used, for example, as high-performance electrodes in supercapacitors, batteries, or other electric storage devices.

Laser cladding of in situ TiB2/Fe composite coating on steel

International Nuclear Information System (INIS)

Du Baoshuai; Zou Zengda; Wang Xinhong; Qu Shiyao

2008-01-01

To enhance the wear resistance of mechanical components, laser cladding has been applied to deposit in situ TiB 2 /Fe composite coating on steel using ferrotitanium and ferroboron as the coating precursor. The phase constituents and microstructure of the composite coating were investigated using X-ray diffraction (XRD), scanning electron micrograph (SEM) and electron probe microanalysis (EPMA). Microhardness tester and block-on-ring wear tester were employed to measure the microhardness and dry-sliding wear resistance of the composite coating. Results show that defect-free composite coating with metallurgical joint to the steel substrate can be obtained. Phases presented in the coating consist of TiB 2 and α-Fe. TiB 2 particles which are formed in situ via nucleation-growth mechanism are distributed uniformly in the α-Fe matrix with blocky morphology. The microhardness and wear properties of the composite coating improved significantly in comparison to the as-received steel substrate due to the presence of the hard reinforcement TiB 2

Nanostructured hydroxyapatite/TiO2 composite coating applied to commercially pure titanium by a co-sputtering technique

International Nuclear Information System (INIS)

Lee, Baek-Hee; Koshizaki, Naoto

2008-01-01

We demonstrate an approach for the coating of nanostructured hydroxyapatite(HAP)/TiO 2 composite on commercially pure Ti (CP-Ti) by a co-sputtering process. HAP/TiO 2 composite film was obtained by controlling the processing pressure. It was observed that decomposition of HAP into CaO was easily induced during sputtering at 0.53 Pa, a typical sputtering condition for film deposition. However, HAP/TiO 2 composite film was obtained with the sputtering pressure of 2.67 Pa. The Ca/P ratio was nearly maintained at 1.66 by sputter deposition at 2.67 Pa. We further confirmed by analysis of plasma spectral emission that the variation of the hydroxyl (OH) radical present was due to the Ar pressure during sputtering. It has been shown that HAP coatings are dependent on the processing pressure, which the hydroxyl radical requires in order to create HAP

Controlling the Biodegradation of Magnesium Implants Through Nanostructured Calcium-Phosphate Coating

Science.gov (United States)

Iskandar, Maria Emil

Magnesium (Mg) alloys, a novel class of degradable, metallic biomaterials, have attracted growing interest as a promising alternative for medical implant and device applications due to their advantageous mechanical and biological properties. Moreover, Mg is biodegradable in the physiological environments. However, the major obstacle for Mg to be used as medical implants is its rapid degradation in physiological fluids. Therefore, the present key challenge lies in controlling Mg degradation rate in the physiological environment. The objective of this study was to develop a nanostructured-hydroxyapatite (nHA) coating on polished Mg implants to control the degradation and bone tissue integration of the implants. The nHA coatings were deposited on Mg using the Spire's patented TPA process to moderate the aggressive degradation of Mg and to improve quick osteointegration between Mg and natural bone. Nanostructured-HA coatings mimic the nanostructure and chemistry of natural bone, which will provide a desirable environment for bone tissue regeneration. Surface morphology, element compositions, and crystal structures were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and x-ray diffractometry (XRD), respectively. SEM images of the deposited nHA-coating was analyzed using ImageJ's quantitative image analysis tool, to determine the nHA-coating particle size and thickness. The degradation of nHA-coated and non-coated Mg samples was investigated by incubating samples in phosphate buffered saline (PBS) and revised simulated body fluid (r-SBF), under standard cell culture conditions. To mimic the in vivo cell response in the physiological environment, rat bone marrow stromal cells (BMSC) were harvested and cultured with nHA-coated and non-coated polished Mg samples to determine cytocompatibilty. The degradation results suggested that the nanocoatings positively mediated Mg degradation. It can therefore be concluded that nHA-coatings

Modification of implant material surface properties by means of oxide nano-structured coatings deposition

Science.gov (United States)

Safonov, Vladimir; Zykova, Anna; Smolik, Jerzy; Rogowska, Renata; Lukyanchenko, Vladimir; Kolesnikov, Dmitrii

2014-08-01

The deposition of functional coatings on the metal surface of artificial joints is an effective way of enhancing joint tribological characteristics. It is well-known that nanostructured oxide coatings have specific properties advantageous for future implant applications. In the present study, we measured the high hardness parameters, the adhesion strength and the low friction coefficient of the oxide magnetron sputtered coatings. The corrosion test results show that the oxide coating deposition had improved the corrosion resistance by a factor of ten for both stainless steel and titanium alloy substrates. Moreover, the hydrophilic nature of coated surfaces in comparison with the metal ones was investigated in the tensiometric tests. The surfaces with nanostructured oxide coatings demonstrated improved biocompatibility for in vitro and in vivo tests, attributed to the high dielectric constants and the high values of the surface free energy parameters.

Solvothermal synthesis of carbon coated N-doped TiO{sub 2} nanostructures with enhanced visible light catalytic activity

Energy Technology Data Exchange (ETDEWEB)

Yan Xuemin, E-mail: yanzhangmm2002@163.com [College of Chemistry and Environmental Engineering, Yangtze University, Jingzhou 434023 (China); Kang Jialing; Gao Lin; Xiong Lin; Mei Ping [College of Chemistry and Environmental Engineering, Yangtze University, Jingzhou 434023 (China)

2013-01-15

Highlights: Black-Right-Pointing-Pointer Chitosan was used as carbon and nitrogen resource to modify TiO{sub 2} nanostructure. Black-Right-Pointing-Pointer Nanocomposites with mesostructure were obtained by one-step solvothermal method. Black-Right-Pointing-Pointer Carbon species were modified on the surface of TiO{sub 2}. Black-Right-Pointing-Pointer Nitrogen was doped into the anatase titania lattice. Black-Right-Pointing-Pointer CTS-TiO{sub 2} nanocomposites show superior visible light photocatalytic activity. - Abstract: Visible light-active carbon coated N-doped TiO{sub 2} nanostructures(CTS-TiO{sub 2}) were prepared by a facile one-step solvothermal method with chitosan as carbon and nitrogen resource at 180 Degree-Sign C. The as-prepared samples were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), N{sub 2} adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy. The CTS-TiO{sub 2} nanocomposites possess anatase phase of nanocrystalline structure with average particle size of about 5-7 nm. A wormhole mesostructure can be observed in the CTS-TiO{sub 2} nanocomposites due to the constituent agglomerated of nanoparticles. It has been evidenced that the nitrogen was doped into the anatase titania lattice and the carbon species were modified on the surface of TiO{sub 2}. The photocatalytic activities of the as-prepared photocatalysts were measured by the degradation of methylene blue (MB) under visible light irradiation at {lambda} {>=} 400 nm. The results show that CTS-TiO{sub 2} nanostructures display a higher visible light photocatalytic activity than pure TiO{sub 2}, commercial P25 and C-coated TiO{sub 2} (C-TiO{sub 2}) photocatalysts. The higher photocatalytic activity could be attributed to the band-gap narrowed by N-doping and the accelerated separation of the photo-generated electrons

Preparation of PbS and PbO nanopowders from new Pb(II)(saccharine) coordination polymers

International Nuclear Information System (INIS)

Aslani, Alireza; Musevi, Seyid Javad; Şahin, Ertan; Yilmaz, Veysel T.

2014-01-01

Highlights: • The complex of compounds “[Pb(H 2 O)(μ-OAc)(μ-sac)] n ” are synthesized at nano and bulk size structurally diverse and show interesting three-dimensional coordination polymers. • Reduction of the particle size of the coordination polymers to a few dozen nanometers results in lower thermal stability when compared to the single crystalline samples. • This study demonstrates that the metal–organic framework may be suitable precursors for the preparation of nanoscale materials with interesting morphologies. - Abstract: Nanopowders and single crystal of new Pb(II) three-dimensional coordination polymer, [Pb(H 2 O)(μ-OAc)(μ-sac)] n “PASAC” were synthesized by a sonochemical and branched tube methods (Yılmaz et al., Z. Anorg. Allg. Chem. 629 (2003) 172). The new nano-structures of Pb(II) coordination polymer were characterized by X-ray crystallography analysis, scanning electron microscopy (SEM), X-ray powder diffraction (XRD), surface analysis (BET), and IR spectroscopy. The crystal structure of these compounds consists of three-dimensional polymeric units. The thermal stability of compounds was studied by thermal gravimetric analysis (TGA) and differential thermal analyses (DTA). PbS and PbO nano-structures were obtained by calcinations of the nano-structures of this coordination polymer at 600 °C

The Role of pH in PEG-b-PAAc Modification of Gadolinium Oxide Nanostructures for Biomedical Applications

Directory of Open Access Journals (Sweden)

Eva Hemmer

2012-01-01

Full Text Available Upconversion and near-infrared emitting Gd2O3:Er3+,Yb3+ nanostructured phosphors (nanoparticles and nanorods for applications in bioimaging have been synthesized by precipitation methods and hydrothermal treatment. Variation of the material synthesis conditions (additives and pH allows controlling particle size (40 nm to μm range and rod aspect ratio (5 to 18. It was shown that PEG-b-PAAc (poly(ethylene glycol poly(acrylic acid block polymer is suitable to provide the required chemical durability, dispersion stability, and noncytotoxic behaviour for biomedical applications, where the coating of Gd2O3 with a protecting and biocompatible layer is essential in order to prevent the release of toxic Gd3+ ions. Physicochemical properties of the Gd2O3:Er3+,Yb3+ nanostructures modified with PEG-b-PAAc have been investigated by TG-DTA, FT-IR, and DLS revealing a strong influence of modification conditions, namely, pH of the reaction media, on the nature of the PEG-b-PAAc layer.

TaxHf1−xB2–SiC multiphase oxidation protective coating for SiC-coated carbon/carbon composites

International Nuclear Information System (INIS)

Ren, Xuanru; Li, Hejun; Fu, Qiangang; Li, Kezhi

2014-01-01

Highlights: • Ta x Hf 1−x B 2 –SiC coating was prepared on SiC coated C/C by in-situ reaction method. • TaB 2 and HfB 2 were introduced in the form of solid solution Ta x Hf 1−x B 2 . • The coating could protect C/C for 1480 h with only 0.57% mass loss at 1773 K in air. • Oxidation layer consists of out Ta–Si–O compound layer and inner SiO 2 glass layer. • Ta–Si–O compound silicate layer presents a better stability than SiO 2 glass layer. - Abstract: A Ta x Hf 1−x B 2 –SiC coating was prepared by in-situ reaction method on SiC coated C/C composites. Ta x Hf 1−x B 2 phase is the form of solid solution between TaB 2 and HfB 2 . Isothermal oxidation behavior at 1773 K and ablation behavior of the coated C/C were tested. Ta x Hf 1−x B 2 –SiC/SiC coating could protect the C/C from oxidation at 1773 K for 1480 h and ablation above 2200 K for 40 s. During oxidation, oxides of Ta and Hf atoms exist as “pinning phases” in the compound glass layer consisted of outer Ta–Si–O compound silicate layer and inner SiO 2 glass layer, which was responsible for the excellent oxidation resistance

Study of SrBi4Ti4O15 (SBTi) dielectric properties of doped PbO

International Nuclear Information System (INIS)

Rodrigues Junior, C.A.; Silva Filho, J.M.; Freitas, D.B.; Oliveira, R.G.M.; Sombra, B.; Sales, J.C.

2012-01-01

The ceramic SrBi 4 Ti 4 O 15 (SBTI), cation-deficient perovskite A 5 B 4 O 15 , was prepared by the method of solid state reaction and then doped with PbO (in the range 2-10% by weight). The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and impedance spectroscopy at room temperature. The X-ray analysis was performed by the Rietveld refinement. The micrographs of the samples show globular-shaped grains (doped PbO). The dielectric properties: dielectric constant (Κ' or έ) and dielectric loss tangent (tan δ), were measured at room temperature in the frequency range 100 Hz - 1 MHz dielectric properties of these 1 MHz sample doped with 10 % PbO showed the dielectric constant Κ'= 168.34 and dielectric loss tangent tanδ, = 7,1.10 -2 . These results show a good possibility of miniaturization of electronic devices such as capacitors. (author)

Photocatalytic degradation of Lissamine Green B dye by using nanostructured sol–gel TiO{sub 2} films

Energy Technology Data Exchange (ETDEWEB)

Ćurković, Lidija, E-mail: lcurkov@fsb.hr [Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, 10000 Zagreb (Croatia); Ljubas, Davor [Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lučića 5, 10000 Zagreb (Croatia); Šegota, Suzana [Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb (Croatia); Bačić, Ivana [Forensic Science Centre Ivan Vučetić, Ministry of the Interior, Ilica 335, Zagreb (Croatia)

2014-08-01

Highlights: • Nanostructured photocatalytic TiO{sub 2} films were prepared by sol–gel methods. • The addition of PEG to the TiO{sub 2} film changes the surface morphology and roughness parameters. • The addition of PEG to the initial sols increases photocatalytic properties of TiO{sub 2}. • LGB water solution could be decolourised within 2 h. • The influence of photolysis and adsorption on the LGB removal from the solution is negligible. - Abstract: Nanostructured sol–gel TiO{sub 2} films were prepared on a glass substrate by means of the dip-coating technique with titanium tetraisopropoxide as a precursor. TiO{sub 2} sols were synthesized with and without the addition of polyethylene glycol (PEG) as a structure-directing agent. The synthesized sol–gel TiO{sub 2} were characterized by XRD, AFM, FTIR and Micro-Raman spectroscopy. The photocatalytic activity of the films was evaluated by the photocatalytic degradation of Lissamine Green B (LGB) dye (dissolved in water) as a model pollutant with the predominant irradiation wavelength of 365 nm (UV-A). It was found that the addition of PEG to the initial sol affects the surface morphology and the photocatalytic properties of prepared sol–gel TiO{sub 2} films. AFM analysis confirmed the presence of nanostructured sol–gel titania films on the glass substrate. Roughness parameters (R{sub a}, R{sub q}, and Z{sub max}) of the sol–gel TiO{sub 2} film with the addition of PEG are higher than the parameters of the sol–gel TiO{sub 2} film without the addition of PEG. The TiO{sub 2} film prepared with the addition of PEG has a higher surface density (a larger active surface area) and better photocatalytic activity in the degradation of the LGB dye solution than the TiO{sub 2} film prepared without the addition of PEG.

Fabrication of superconducting MgB2 nanostructures by an electron beam lithography-based technique

Science.gov (United States)

Portesi, C.; Borini, S.; Amato, G.; Monticone, E.

2006-03-01

In this work, we present the results obtained in fabrication and characterization of magnesium diboride nanowires realized by an electron beam lithography (EBL)-based method. For fabricating MgB2 thin films, an all in situ technique has been used, based on the coevaporation of B and Mg by means of an e-gun and a resistive heater, respectively. Since the high temperatures required for the fabrication of good quality MgB2 thin films do not allow the nanostructuring approach based on the lift-off technique, we structured the samples combining EBL, optical lithography, and Ar milling. In this way, reproducible nanowires 1 μm long have been obtained. To illustrate the impact of the MgB2 film processing on its superconducting properties, we measured the temperature dependence of the resistance on a nanowire and compared it to the original magnesium diboride film. The electrical properties of the films are not degraded as a consequence of the nanostructuring process, so that superconducting nanodevices may be obtained by this method.

The Functionalization of Nanostructures and Their Potential Applications in Edible Coatings

Directory of Open Access Journals (Sweden)

Ricardo M. González-Reza

2018-04-01

Full Text Available Nowadays, edible coatings incorporated with nanostructures as systems of controlled release of flavors, colorants and/or antioxidants and antimicrobial substances, also used for thermal and environmental protection of active compounds, represent a gap of opportunity to increase the shelf life of food highly perishable, as well as for the development of new products. These functionalized nanostructures have the benefit of incorporating natural substances obtained from the food industry that are rich in polyphenols, dietary fibers, and antimicrobial substances. In addition, the polymers employed on its preparation, such as polysaccharides, solid lipids and proteins that are low cost and developed through sustainable processes, are friendly to the environment. The objective of this review is to present the materials commonly used in the preparation of nanostructures, the main ingredients with which they can be functionalized and used in the preparation of edible coatings, as well as the advances that these structures have represented when used as controlled release systems, increasing the shelf life and promoting the development of new products that meet the characteristics of functionality for fresh foods ready to eat.

Nanostructured titanium–silver coatings with good antibacterial activity and cytocompatibility fabricated by one-step magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Bai, Long [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan (China); Hang, Ruiqiang, E-mail: hangruiqiang@tyut.edu.cn [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan (China); Gao, Ang [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Zhang, Xiangyu; Huang, Xiaobo; Wang, Yueyue; Tang, Bin [Research Institute of Surface Engineering, Taiyuan University of Technology, Taiyuan (China); Zhao, Lingzhou, E-mail: zhaolingzhou1983@hotmail.com [State Key Laboratory of Military Stomatology, Department of Periodontology, School of Stomatology, The Fourth Military Medical University, Xi’an (China); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2015-11-15

Graphical abstract: - Highlights: • We fabricate Ti–Ag coatings with different Ag contents and surface morphologies. • The Ti–Ag coatings possess long-term antibacterial ability. • Increased Ag contents in the coatings leads to enhanced osteoblast functions. - Abstract: Bacterial infection and loosing are serious complications for biomedical implants in the orthopedic, dental, and other biomedical fields and the ideal implants should combine good antibacterial ability and bioactivity. In this study, nanostructured titanium–silver (Ti–Ag) coatings with different Ag contents (1.2 to 21.6 at%) are prepared on Ti substrates by magnetron sputtering. As the Ag concentration is increased, the coatings change from having dense columnar crystals to sparse ones and eventually no columnar structure. The Ti–Ag coatings can effectively kill Staphylococcus aureus during the first few days and remain moderately antibacterial after immersion for 75 days. Compared to pure Ti, the Ti–Ag coatings show good cytocompatibility as indicated by good osteoblast adhesion, proliferation, intracellular total protein synthesis, and alkaline phosphatase (ALP) activity. In addition, cell spreading, collagen secretion, and extracellular matrix mineralization are promoted on the coatings with the proper Ag contents due to the nanostructured morphological features. Our results indicate that favorable antibacterial activity and osseointegration ability can be simultaneously achieved by regulating the Ag contents in Ti–Ag coatings.

Highly mesoporous α-Fe2O3 nanostructures: preparation, characterization and improved photocatalytic performance towards Rhodamine B (RhB)

International Nuclear Information System (INIS)

Bharathi, S; Nataraj, D; Mangalaraj, D; Masuda, Y; Senthil, K; Yong, K

2010-01-01

Single-crystalline porous hematite nanorods and spindle-like nanostructures were successfully synthesized by a low temperature reflux condensation method. Two different iron sources, namely, FeCl 3 ·6H 2 O and Fe(NO 3 ) 3 ·9H 2 O, were hydrolyzed in the presence of urea to selectively prepare nanorods and spindle-like nanostructures. Initially, the akagenite phase was obtained by refluxing the precursor for 12 h and then the as-prepared akagenite nanostructures were transformed to porous hematite nanostructures upon calcination at 300 0 C for 1 h. The shape and the aspect ratio of the 12 h refluxed sample was retained even after calcination and this shows the topotactic transformation of the nanostructure. TEM and HRTEM investigations have shown the porous nature of the prepared sample. Brunauer-Emmett-Teller and Barret-Joyner-Halenda measurements have shown a large surface area and distribution of mesopores in the nanorods sample. The photocatalytic activity of the prepared nanostructures towards RhB has reflected this variation in the pore size distribution and specific surface area, by showing a higher activity for the nanorods sample. Magnetic studies by VSM have shown a weak ferromagnetic behaviour in both the samples due to shape anisotropy.

Laser cladding of in situ TiB{sub 2}/Fe composite coating on steel

Energy Technology Data Exchange (ETDEWEB)

Du Baoshuai; Zou Zengda [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Wang Xinhong [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China)], E-mail: xinhongwang@sdu.edu.cn; Qu Shiyao [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China)

2008-08-15

To enhance the wear resistance of mechanical components, laser cladding has been applied to deposit in situ TiB{sub 2}/Fe composite coating on steel using ferrotitanium and ferroboron as the coating precursor. The phase constituents and microstructure of the composite coating were investigated using X-ray diffraction (XRD), scanning electron micrograph (SEM) and electron probe microanalysis (EPMA). Microhardness tester and block-on-ring wear tester were employed to measure the microhardness and dry-sliding wear resistance of the composite coating. Results show that defect-free composite coating with metallurgical joint to the steel substrate can be obtained. Phases presented in the coating consist of TiB{sub 2} and {alpha}-Fe. TiB{sub 2} particles which are formed in situ via nucleation-growth mechanism are distributed uniformly in the {alpha}-Fe matrix with blocky morphology. The microhardness and wear properties of the composite coating improved significantly in comparison to the as-received steel substrate due to the presence of the hard reinforcement TiB{sub 2}.

Electrochemical disinfection of simulated ballast water on PbO2/graphite felt electrode.

Science.gov (United States)

Chen, Shuiping; Hu, Weidong; Hong, Jianxun; Sandoe, Steve

2016-04-15

A novel PbO2/graphite felt electrode was constructed by electrochemical deposition of PbO2 on graphite felt and characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) analysis. The prepared electrode is a viable technology for inactivation of Escherichia coli, Enterococcus faecalis, and Artemia salina as indicator organisms in simulated ballast water treatment, which meets the International Maritime Organization (IMO) Regulation D-2. The effects of contact time and current density on inactivation were investigated. An increase in current density generally had a beneficial effect on the inactivation of the three species. E.faecalis and A.salina were more resistant to electrochemical disinfection than E. coli. The complete disinfection of E.coli was achieved in <8min at an applied current density of 253A/m(2). Complete inactivation of E. faecalis and A.salina was achieved at the same current density after 60 and 40min of contact time, respectively. A. salina inactivation follows first-order kinetics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Formation and surface characterization of nanostructured Al2O3 ...

Indian Academy of Sciences (India)

Administrator

Page 1. Electronic Supplementary Material. Graphical abstract. Formation and surface characterization of nanostructured Al2O3–TiO2 coatings by Vairamuthu Raj and Mohamed Sirajudeen Mumjitha. (pp 1411–1418).

Evaluations of MgB2 Coatings on 2'' Copper Discs for Superconducting Radio Frequency Applications

Science.gov (United States)

Withanage, Wenura; Tan, Teng; Lee, Namhoon; Banjade, Huta; Eremeev, Grigory; Welander, Paul; Valente-Feliciano, Anne-Marie; Kustom, Robert; Wolak, Matthäus; Nassiri, Alireza; Xi, Xiaoxing

We propose that coating the inner walls of copper RF cavities with superconducting MgB2 (Tc = 39 K) can result in a viable alternative to the already established niobium-based SRF technology. This approach improves the thermal conductivity, allows for operation at higher temperatures, and reduces the need for large helium refrigeration, thereby resulting in lower operational costs. For our studies, we grew MgB2 films via hybrid physical chemical vapor deposition (HPCVD) on 2'' Cu substrates. Since Mg and Cu readily form an alloy at higher temperatures, the HPCVD setup was modified in order to achieve lower deposition temperatures, minimize alloy formation, and provide high quality MgB2 films. This method yielded MgB2 coatings on 2'' Cu discs with transition temperatures around 38 K. The samples were characterized with regards to their RF attributes and showed similar performance in comparison to Nb reference samples. The presented results show that MgB2 coated copper can be a suitable alternative for use in SRF cavities.

Improved tribological properties of TiC with porous nanostructured TiO2 intermediate layer

International Nuclear Information System (INIS)

Shanaghi, Ali; Ahangarani, Shahrokh; Sabour Rouhaghdam, Ali Reza; Chu, Paul K.

2011-01-01

Highlights: ► The porous TiO 2 nanoparticle coating is deposited as an intermediate layer on steel. ► A homogenous and low friction TiC nanostructure coating is deposited by plasma CVD. ► Intermediate layer can be determined the nucleation and growth of the TiC coating. ► The porous interlayer improves the friction and wear of the TiC nanostructure coating. - Abstract: The mismatch in the thermal expansion coefficients between TiC coatings and steel substrates and residual stress in the TiC degrade the tribological properties. In this work, a porous nanostructured TiO 2 coating is deposited as an intermediate layer on hot-work steel (H 11 ) before final deposition of the TiC film. This intermediate layer is expected to reduce the interfacial energy, decreases the thermal mismatch between TiC and steel, and improves the tribological properties. Grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and pin-on-disk are used to study the structure as well as tribological properties such as friction, wear, and hardness. Our results reveal that the porous TiO 2 interlayer improves the friction, wear, hardness, and elastic modulus of the system.

Synthesis, characterization, and applications of electroactive polymeric nanostructures for organic coatings

Science.gov (United States)

Suryawanshi, Abhijit Jagnnath

Electroactive polymers (EAP) such as polypyrrole (PPy) and polyaniline (PANI) are being explored intensively in the scientific community. Nanostructures of EAPs have low dimensions and high surface area enabling them to be considered for various useful applications. These applications are in several fields including corrosion inhibition, capacitors, artificial muscles, solar cells, polymer light emitting diodes, and energy storage devices. Nanostructures of EAPs have been synthesized in different morphologies such as nanowires, nanorods, nanotubes, nanospheres, and nanocapsules. This variety in morphology is traditionally achieved using soft templates, such as surfactant micelles, or hard templates, such as anodized aluminum oxide (AAO). Templates provide stability and groundwork from which the polymer can grow, but the templates add undesirable expense to the process and can change the properties of the nanoparticles by integrating its own properties. In this study a template free method is introduced to synthesize EAP nanostructures of PPy and PANI utilizing ozone oxidation. The simple techniques involve ozone exposure to the monomer solution to produce aqueous dispersions of EAP nanostructures. The synthesized nanostructures exhibit uniform morphology, low particle size distribution, and stability against agglomeration. Ozone oxidation is further explored for the synthesis of silver-PPy (Ag-PPy) core-shell nanospheres (CSNs). Coatings containing PPy nanospheres were formulated to study the corrosion inhibition efficiency of PPy nanospheres. Investigation of the coatings using electrochemical techniques revealed that the PPy nanospheres may provide corrosion inhibition against filiform corrosion by oxygen scavenging mechanism. Finally, organic corrosion inhibitors were incorporated in PPy to develop efficient corrosion inhibiting systems, by using the synergistic effects from PPy and organic corrosion inhibitors.

A biodegradable AZ91 magnesium alloy coated with a thin nanostructured hydroxyapatite for improving the corrosion resistance.

Science.gov (United States)

Mukhametkaliyev, T M; Surmeneva, M A; Vladescu, A; Cotrut, C M; Braic, M; Dinu, M; Vranceanu, M D; Pana, I; Mueller, M; Surmenev, R A

2017-06-01

The main aim of this study was to investigate the properties of an AZ91 alloy coated with nanostructured hydroxyapatite (HA) prepared by radio frequency (RF) magnetron sputtering. The bioactivity and biomineralization of the AZ91 magnesium alloy coated with HA were investigated in simulated body fluid (SBF) via an in vitro test. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) analyses were performed. The samples were immersed in SBF to study the ability of the surface to promote the formation of an apatite layer as well as corrosion resistance and mass change of the HA-coated AZ91 alloy. Electrochemical tests were performed to estimate the corrosion behaviour of HA-coated and uncoated samples. The results revealed the capability of the HA coating to significantly improve the corrosion resistance of the uncoated AZ91 alloy. Copyright © 2017 Elsevier B.V. All rights reserved.

Controlling the degradation rate of AZ91 magnesium alloy via sol–gel derived nanostructured hydroxyapatite coating

Energy Technology Data Exchange (ETDEWEB)

Rojaee, Ramin, E-mail: raminrojaee@aim.com [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Raeissi, Keyvan [Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of)

2013-10-15

Magnesium (Mg) alloys have been introduced as new generation of biodegradable orthopedic materials in recent years since it has been proved that Mg is one of the main minerals required for osseous tissue revival. The main goal of the present study was to establish a desired harmony between the necessities of orthopedic patient body to Mg{sup 2+} ions and degradation rate of the Mg based implants as a new class of biodegradable/bioresorbable materials. This prospect was followed by providing a sol–gel derived nanostructured hydroxyapatite (n-HAp) coating on AZ91 alloy using dip coating technique. Phase structural analysis, morphology study, microstructure characterization, and functional group identification were performed using X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The prepared samples were immersed in simulated body fluid in order to study the formation of apatite-like precipitations, barricade properties of the n-HAp coating, and to estimate the dosage of released Mg{sup 2+} ions within a specified and limited time of implantation. Electrochemical polarization tests were carried out to evaluate and compare the corrosion behavior of the n-HAp coated and uncoated samples. The changes of the in vitro pH values were also evaluated. Results posed the noticeable capability of n-HAp coating on stabilizing alkalization behavior and improving the corrosion resistance of AZ91 alloy. It was concluded that n-HAp coated AZ91 alloy could be a good candidate as a type of biodegradable implant material for biomedical applications. - Highlights: • Nanostructured hydroxyapatite coatings were applied on Mg based alloy. • The whole corrosion process of Mg based alloy was controlled in body fluid. • This coating was able to act as a barrier against further release of Mg{sup 2+} ions. • The coating improved the stabilization of Mg alkalization behavior.

Controlling the degradation rate of AZ91 magnesium alloy via sol–gel derived nanostructured hydroxyapatite coating

International Nuclear Information System (INIS)

Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan

2013-01-01

Magnesium (Mg) alloys have been introduced as new generation of biodegradable orthopedic materials in recent years since it has been proved that Mg is one of the main minerals required for osseous tissue revival. The main goal of the present study was to establish a desired harmony between the necessities of orthopedic patient body to Mg 2+ ions and degradation rate of the Mg based implants as a new class of biodegradable/bioresorbable materials. This prospect was followed by providing a sol–gel derived nanostructured hydroxyapatite (n-HAp) coating on AZ91 alloy using dip coating technique. Phase structural analysis, morphology study, microstructure characterization, and functional group identification were performed using X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The prepared samples were immersed in simulated body fluid in order to study the formation of apatite-like precipitations, barricade properties of the n-HAp coating, and to estimate the dosage of released Mg 2+ ions within a specified and limited time of implantation. Electrochemical polarization tests were carried out to evaluate and compare the corrosion behavior of the n-HAp coated and uncoated samples. The changes of the in vitro pH values were also evaluated. Results posed the noticeable capability of n-HAp coating on stabilizing alkalization behavior and improving the corrosion resistance of AZ91 alloy. It was concluded that n-HAp coated AZ91 alloy could be a good candidate as a type of biodegradable implant material for biomedical applications. - Highlights: • Nanostructured hydroxyapatite coatings were applied on Mg based alloy. • The whole corrosion process of Mg based alloy was controlled in body fluid. • This coating was able to act as a barrier against further release of Mg 2+ ions. • The coating improved the stabilization of Mg alkalization behavior

Structural and optical properties of ZnO nanostructures electrochemically synthesized on AZO/Ag/AZO-multilayer-film-coated polyethersulfone substrates

International Nuclear Information System (INIS)

Oh, Dohyun; Yoo, Chanho; No, Youngsoo; Kim, Suyoun; Kim, Taewhan; Cho, Woonjo; Kim, Jinyoung

2012-01-01

ZnO nanostructures were formed on Al-doped ZnO (AZO)/Ag/AZO-multilayer-film-coated flexible polyethersulfone (PES) substrates at low temperature by using an electrochemical deposition method. The resistivity of the AZO/Ag/AZO multilayer films decreased with increasing thickness of the Ag film. X-ray diffraction patterns for the ZnO nanostructures showed that the crystal structure of the ZnO was hexagonal wurtzite and that the orientation was along the c-axis perpendicular to the substrate. Scanning electron microscopy images showed that the ZnO nanostructures grown at current densities of - 1.0 and - 1.5 mA/cm 2 were ZnO nanorods with diameters of 150 nm and ZnO nanoflowers with a planar dimension, respectively. Photoluminescence spectra showed that the band-edge emission peak of the ZnO nanostructures dominantly appeared in the ultraviolet region. These results showed that ZnO nanorods and nanoflowers with high quality were synthesized on AZO/Ag/AZO-multilayer-film-coated PES substrates.

Tribological properties of B{sub 4}C-TiB{sub 2}-TiC-Ni cermet coating produced by HVOF

Energy Technology Data Exchange (ETDEWEB)

Rafiei, Mahdi [Islamic Azad Univ., Najafabad (Iran, Islamic Republic of). Dept. of Materials Engineering; Isfahan Univ. of Technology, Isfahan (Iran, Islamic Republic of). Depr. of Materials Engineering; Shamanian, Morteza; Salehi, Mehdi [Isfahan Univ. of Technology, Isfahan (Iran, Islamic Republic of). Depr. of Materials Engineering; Mostaan, Hossein [Arak Univ., Arak (Iran, Islamic Republic of). Dept. of Materials and Metallurgical Engineering

2017-08-15

In this study, B{sub 4}C-TiB{sub 2}-TiC-Ni coating was sprayed on the surface of 4130 steel by high velocity oxy-fuel torch. The tribological behavior of samples was studied by ball on disk wear testing. Structural evolution of the coating was analyzed by X-ray diffractometry. The microstructure of the coating, wear track and Al{sub 2}O{sub 3} ball was investigated by scanning electron microscopy, field emission scanning electron microscopy and optical microscopy. Elemental analysis of the wear track was done by energy dispersive X-ray spectroscopy. It was found that a cermet coating containing B{sub 4}C, TiB{sub 2}, TiC and Ni phases with good bonding to the 4130 steel substrate with no sign of any cracking or pores was formed. The wear mechanism of the composite coating was delamination. The friction coefficient of samples was decreased with increasing load because of higher frictional heat and creation of more oxide islands.

Facile Synthesis and Tensile Behavior of TiO2 One-Dimensional Nanostructures

Directory of Open Access Journals (Sweden)

Li Shu-you

2009-01-01

Full Text Available Abstract High-yield synthesis of TiO2 one-dimensional (1D nanostructures was realized by a simple annealing of Ni-coated Ti grids in an argon atmosphere at 950 °C and 760 torr. The as-synthesized 1D nanostructures were single crystalline rutile TiO2 with the preferred growth direction close to [210]. The growth of these nanostructures was enhanced by using catalytic materials, higher reaction temperature, and longer reaction time. Nanoscale tensile testing performed on individual 1D nanostructures showed that the nanostructures appeared to fracture in a brittle manner. The measured Young’s modulus and fracture strength are ~56.3 and 1.4 GPa, respectively.

Freezing polystyrene-b-poly(2-vinylpyridine) micelle nanoparticles with different nanostructures and sizes.

Science.gov (United States)

Fan, Hailong; Jin, Zhaoxia

2014-04-28

Herein we report how to control the nanostructures and sizes of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) nanoparticles via manipulating freezing in solvent-exchange. By characterizing and analyzing the distinct structural features of the obtained nanoparticles, we recognized that micelle self-assembly happens in the precipitation of PS-b-P2VP when water is added into the block copolymer (BCP) solution. Solvent properties significantly influence micelle types that are vesicles in acetone/H2O and spherical micelles in tetrahydrofuran/H2O, respectively, thus further inducing different frozen nanostructures of the obtained nanoparticles, onion-like in acetone/H2O and large compound micelles in tetrahydrofuran/H2O. By changing the concentration of the block copolymers and the Vsolvent/VH2O ratio to modify the freezing stage at which block copolymer micelles are frozen, we can further control the size of the nanoparticles. Moreover, small molecules (phosphotungstic acid, pyrene, 1-pyrenebutyric acid) can be trapped into the block copolymer nanoparticles via the freezing process. Their distribution in the nanoparticles relies not only on the solvent property, but also on their interactions with block copolymers. The hybrid nanoparticles with ordered distribution of small molecules can be further changed to partially-void nanoparticles. Our study demonstrated that manipulating the freezing of block copolymers in the solvent exchange process is a simple and controllable fabrication method to generate BCP nanoparticles with different architectures.

Nanostructured multielement (TiHfZrNbVTa)N coatings before and after implantation of N+ ions (10{sup 18} cm{sup −2}): Their structure and mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Pogrebnjak, A.D., E-mail: alexp@i.ua [Sumy State University, Department of Nanoelectronics, 40007, R.-Korsakova 2, Sumy (Ukraine); Bondar, O.V., E-mail: oleksandr.v.bondar@gmail.com [Sumy State University, Department of Nanoelectronics, 40007, R.-Korsakova 2, Sumy (Ukraine); Borba, S.O. [Sumy State University, Department of Nanoelectronics, 40007, R.-Korsakova 2, Sumy (Ukraine); Abadias, G. [Institut Pprime, CNRS, Université de Poitiers, ISAE-ENSMA, F86962 Futuroscope Chasseneuil (France); Konarski, P. [Tele and Radio Research Institute, Ratuszowa 11, 03-450 Warsaw (Poland); Plotnikov, S.V. [D. Serikbaev East-Kazakhstan State Technical University, 070004, Ust-Kamenogorsk, 69 Protozanov St. (Kazakhstan); Beresnev, V.M. [V.N. Karazin Kharkiv National University, 61022, Svobody Sq. 4, Kharkiv (Ukraine); Kassenova, L.G. [Kazakh University of Economics, Finance and International Trade, St. Zhubanov 7, 010005 Astana (Kazakhstan); Drodziel, P. [Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin (Poland)

2016-10-15

Highlights: • (TiZrHfVNbTa)N coatings were deposited by vacuum–arc evaporation of a cathode. • Nanostructured coatings were investigated experimentally and by MD simulations. • Good correlation between experimental data and simulation results is observed. • Ion implantation formed amorphous, nanocrystalline and nanostructured layers. • Hardness changed from 12 GPa in the implanted layer to 38 GPa with the depth. - Abstract: Multielement high entropy alloy (HEA) nitride (TiHfZrNbVTa)N coatings were deposited by vacuum arc and their structural and mechanical stability after implantation of high doses of N{sup +} ions, 10{sup 18} cm{sup −2}, were investigated. The crystal structure and phase composition were characterized by X-ray diffraction (XRD) and Transmission Electron Microscopy, while depth-resolved nanoindentation tests were used to determine the evolution of hardness and elastic modulus along the implantation depth. XRD patterns show that coatings exhibit a main phase with fcc structure, which preferred orientation varies from (1 1 1) to (2 0 0), depending on the deposition conditions. First-principles calculations reveal that the presence of Nb atoms could favor the formation of solid solution with fcc structure in multielement HEA nitride. TEM results showed that amorphous and nanostructured phases were formed in the implanted coating sub-surface layer (∼100 nm depth). Concentration of nitrogen reached 90 at% in the near-surface layer after implantation, and decreased at higher depth. Nanohardness of the as-deposited coatings varied from 27 to 38 GPa depending on the deposition conditions. Ion implantation led to a significant decrease of the nanohardness to 12 GPa in the implanted region, while it reaches 24 GPa at larger depths. However, the H/E ratio is ⩾0.1 in the sub-surface layer due to N{sup +} implantation, which is expected to have beneficial effect on the wear properties.

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

Energy Technology Data Exchange (ETDEWEB)

Dave, V., E-mail: vdaditya1000@gmail.com [Department of Electrical Engineering,College of Technology and Engineerin, MPUAT Udaipur, 313001,India (India); Rao, G. P., E-mail: ragrao38@gmail.com; Tiwari, G. S., E-mail: tiwarigsin@yahoo.com [Department of Farm Machinery and Power Engineering, MPUAT Udaipur, 313001,India (India); Sanger, A., E-mail: amitsangeriitr@gmail.com; Kumar, A., E-mail: 01ashraj@gmail.com; Chandra, R., E-mail: ramesfic@gmail.com [Institute Instrumentation Centre, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

2016-04-13

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

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

International Nuclear Information System (INIS)

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

2016-01-01

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

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

Science.gov (United States)

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

2016-04-01

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

Coatings synthesised by the pulsed laser ablation of a B{sub 4}C/W{sub 2}B{sub 5} ceramic composite

Energy Technology Data Exchange (ETDEWEB)

Tadadjeu Sokeng, I., E-mail: ifriky@tlabs.ac.za [Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville campus, PO Box 1906, Bellville, 7530 (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Ngom, B.D. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Laboratoire de Photonique et de Nanofrabrication, Groupes de physique du Solide et Sciences des Matriaux (GPSSM), Facult des sciences et Techniques Universit Cheikh Anta Diop de Dakar (UCAD), B.P. 25114 Dakar, Fann Dakar (Senegal); Msimanga, M. [iThemba LABS Gauten, Private Bag 11, WITS 2050 Johannesburg (South Africa); Nuru, Z.Y.; Kotsedi, L.; Maaza, M. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Van Zyl, R.R. [Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville campus, PO Box 1906, Bellville, 7530 (South Africa)

2015-10-30

A pellet of B{sub 4}C/W{sub 2}B{sub 5} ceramic composite was characterised and subjected to pulsed laser ablation for the deposition of coatings on corning glass substrates. We reports an attempt to produce coatings from B{sub 4}C/W{sub 2}B{sub 5} by pulsed laser deposition (PLD). The thermal, electric and mechanical properties of B{sub 4}C/W{sub 2}B{sub 5} suggest that coatings synthesised from this composite can be used for space applications. The samples were characterised using X-ray Diffraction, Atomic Force Microscopy and Heavy Ion Elastic Recoil Detection Analysis. The characterisation of the samples deposited on soda lime corning glass showed that the laser energy used in this PLD was enough to obtain non amorphous coatings formed by some alteration of the tungsten carbide crystal lattice at room temperature, and that there was no stoichiometry transfer as would be expected from PLD. The coating also showed space applicable features worth investigating. - Highlights: • B{sub 4}C/W{sub 2}B{sub 5} ceramic composite was ablated for deposition on corning glass subtrates. • Non-amorphous coating was obtained at room temperature. • There was no stoichiometry transfer as would be expected from Pulsed Laser Deposition.

Matrix coatings based on anodic alumina with carbon nanostructures in the pores

Science.gov (United States)

Gorokh, G. G.; Pashechko, M. I.; Borc, J. T.; Lozovenko, A. A.; Kashko, I. A.; Latos, A. I.

2018-03-01

The nanoporous anodic alumina matrixes thickness of 1.5 mm and pore sizes of 45, 90 and 145 nm were formed on Si substrates. The tubular carbon nanostructures were synthesized into the matrixes pores by pyrolysis of fluid hydrocarbon xylene with 1% ferrocene. The structure and composition of the matrix coatings were examined by scanning electron microscopy, Auger analysis and Raman spectroscopy. The carbon nanostructures completely filled the pores of templates and uniformly covered the tops. The structure of carbon nanostructures corresponded to the structure of multiwall carbon nanotubes. Investigations of mechanical and tribological properties of nanostructured oxide-carbon composite performed by scratching and nanoindentation showed nonlinear dependencies of the frictional force, penetration depth of the cantilever, hardness and plane strain modulus on the load. It was found that the microhardness of the samples increases with reduced of alumina pore diameter, and the penetration depth of the cantilever into the film grows with carbon nanostructures size. The results showed the high mechanical strength of nanostructured oxide-carbon composite.

Highly mesoporous {alpha}-Fe{sub 2}O{sub 3} nanostructures: preparation, characterization and improved photocatalytic performance towards Rhodamine B (RhB)

Energy Technology Data Exchange (ETDEWEB)

Bharathi, S; Nataraj, D [Thin Films and Nanomaterials Lab, Department of Physics, Bharathiar University, Coimbatore 641046 (India); Mangalaraj, D [DRDO-BU Centre for Life Sciences, Bharathiar University, Coimbatore 641046 (India); Masuda, Y [National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560 (Japan); Senthil, K [Centre for Information Materials, Pohang University of Science and Technology, Pohang (Korea, Republic of); Yong, K, E-mail: de.natraj@gmail.co [Department of Chemical Engineering, Pohang University of Science and Technology, Pohang (Korea, Republic of)

2010-01-13

Single-crystalline porous hematite nanorods and spindle-like nanostructures were successfully synthesized by a low temperature reflux condensation method. Two different iron sources, namely, FeCl{sub 3{center_dot}}6H{sub 2}O and Fe(NO{sub 3}){sub 3{center_dot}}9H{sub 2}O, were hydrolyzed in the presence of urea to selectively prepare nanorods and spindle-like nanostructures. Initially, the akagenite phase was obtained by refluxing the precursor for 12 h and then the as-prepared akagenite nanostructures were transformed to porous hematite nanostructures upon calcination at 300 {sup 0}C for 1 h. The shape and the aspect ratio of the 12 h refluxed sample was retained even after calcination and this shows the topotactic transformation of the nanostructure. TEM and HRTEM investigations have shown the porous nature of the prepared sample. Brunauer-Emmett-Teller and Barret-Joyner-Halenda measurements have shown a large surface area and distribution of mesopores in the nanorods sample. The photocatalytic activity of the prepared nanostructures towards RhB has reflected this variation in the pore size distribution and specific surface area, by showing a higher activity for the nanorods sample. Magnetic studies by VSM have shown a weak ferromagnetic behaviour in both the samples due to shape anisotropy.

Shear strength of reinforced concrete beams strengthened by P.B.O. fiber mesh under loading

Directory of Open Access Journals (Sweden)

Blikharskyy Zinoviy

2017-01-01

Full Text Available This article presents experimental study of sheer strength of reinforced concrete beams without transverse steel reinforcement, which strengthened by composite materials. The feature of tests is that the beams’ strengthening is made under simultaneous action of loading. The research program involves a series of test beams with size 2100 × 200 × 100 mm and which contains control sample and three reinforced samples by reinforcing FRCM system. FRCM system consisting of two components: mineral mortar based on modified cement Ruredil X Mesh M750 and reinforcing P.B.O. fiber mesh Ruredil X Mesh Gold (Italy. The strength research of test samples was carried out with the shear distance to effective depth ratio a/d = 2. The strengthening loading levels were selected at 0.0, 0.3, 0.5 from shear strength of non strengthened control sample. As a result of experimental studies we found that during strengthening design the inclined cross section of beams we should take into account the existing level of loading. Using the strengthening system Ruredil X Mesh Gold the strengthening effect is reduced at 2.8 to 2.9 times while the existing level of loading increase from 0 to 50%.

Nanostructured transparent conducting oxide electrochromic device

Science.gov (United States)

Milliron, Delia; Tangirala, Ravisubhash; Llordes, Anna; Buonsanti, Raffaella; Garcia, Guillermo

2016-05-17

The embodiments described herein provide an electrochromic device. In an exemplary embodiment, the electrochromic device includes (1) a substrate and (2) a film supported by the substrate, where the film includes transparent conducting oxide (TCO) nanostructures. In a further embodiment, the electrochromic device further includes (a) an electrolyte, where the nanostructures are embedded in the electrolyte, resulting in an electrolyte, nanostructure mixture positioned above the substrate and (b) a counter electrode positioned above the mixture. In a further embodiment, the electrochromic device further includes a conductive coating deposited on the substrate between the substrate and the mixture. In a further embodiment, the electrochromic device further includes a second substrate positioned above the mixture.

High-temperature mass spectrometric study of the vaporization processes and thermodynamic properties of melts in the PbO-B2O3-SiO2 system.

Science.gov (United States)

Stolyarova, V L; Lopatin, S I; Shilov, A L; Shugurov, S M

2013-07-15

The unique properties of the PbO-B2O3-SiO2 system, especially its extensive range of glass-forming compositions, make it valuable for various practical applications. The thermodynamic properties and vaporization of PbO-B2O3-SiO2 melts are not well established so far and the data obtained on these will be useful for optimization of technology and thermodynamic modeling of glasses. High-temperature Knudsen effusion mass spectrometry was used to study vaporization processes and to determine the partial pressures of components of the PbO-B2O3-SiO2 melts. Measurements were performed with a MS-1301 mass spectrometer. Vaporization was carried out using two quartz effusion cells containing the sample under study and pure PbO (reference substance). Ions were produced by electron ionization at an energy of 25 eV. To facilitate interpretation of the mass spectra, the appearance energies of ions were also measured. Pb, PbO and O2 were found to be the main vapor species over the samples studied at 1100 K. The PbO activities as a function of the composition of the system were derived from the measured PbO partial pressures. The B2O3 and SiO2 activities, the Gibbs energy of formation, the excess Gibbs energy of formation and mass losses in the samples studied were calculated. Partial pressures of the vapor species over PbO-B2O3-SiO2 melts were measured at 1100 K in the wide range of compositions using the Knudsen mass spectrometric method. The data enabled the PbO, B2O3, and SiO2 activities in these melts to be derived and provided evidence of their negative deviations from ideal behavior. Copyright © 2013 John Wiley & Sons, Ltd.

Preparation and characterization of Eosin B- and Erythrosin J-sensitized nanostructured NiO thin film photocathodes

Energy Technology Data Exchange (ETDEWEB)

Vera, F. [Instituto de Quimica, Universidad Catolica de Valparaiso, Valparaiso (Chile); Schrebler, R. [Instituto de Quimica, Universidad Catolica de Valparaiso, Valparaiso (Chile); Munoz, E. [Instituto de Quimica, Universidad Catolica de Valparaiso, Valparaiso (Chile); Suarez, C. [Instituto de Quimica, Universidad Catolica de Valparaiso, Valparaiso (Chile); Cury, P. [Instituto de Quimica, Universidad Catolica de Valparaiso, Valparaiso (Chile); Gomez, H. [Instituto de Quimica, Universidad Catolica de Valparaiso, Valparaiso (Chile); Cordova, R. [Instituto de Quimica, Universidad Catolica de Valparaiso, Valparaiso (Chile); Marotti, R.E. [Instituto de Fisica, Facultad de Ingenieria, Universidad de la Republica, Herrera y Reissig 565, C.C. 30, 11000 Montevideo (Uruguay); Dalchiele, E.A. [Instituto de Fisica, Facultad de Ingenieria, Universidad de la Republica, Herrera y Reissig 565, C.C. 30, 11000 Montevideo (Uruguay)]. E-mail: dalchiel@fing.edu.uy

2005-11-01

Nickel oxide (NiO) thin films were prepared onto ITO/glass substrates by spin-coating, dipping and electrochemically. Studies of the morphological and structural properties of the films were done by atomic force microscopy (AFM). Photoelectrochemical and optical experiments were carried out in order to characterize the semiconductor properties of the nanostructured NiO thin films. The experiments were also done for Eosin B- and Erythrosin J-sensitized nanostructured NiO films, with the aim to visualize their potential application as photocatodes in tandem dye-sensitized solar cells (TDSSC). The NiO grown by dipping was the one presenting the best morphological properties. The photoelectrochemical results for all the bare NiO, NiO-Eosin B and NiO-Erythrosin J/electrolyte (I{sub 2}/I{sup -}) systems showed a p-type behavior. An enhancement in the photocurrent has been observed for the systems sensitized with the dyes. For the NiO/Erythrosin J system the enhancement of the current under illumination in comparison to the dark current was about 200%.

Preparation and characterization of Eosin B- and Erythrosin J-sensitized nanostructured NiO thin film photocathodes

International Nuclear Information System (INIS)

Vera, F.; Schrebler, R.; Munoz, E.; Suarez, C.; Cury, P.; Gomez, H.; Cordova, R.; Marotti, R.E.; Dalchiele, E.A.

2005-01-01

Nickel oxide (NiO) thin films were prepared onto ITO/glass substrates by spin-coating, dipping and electrochemically. Studies of the morphological and structural properties of the films were done by atomic force microscopy (AFM). Photoelectrochemical and optical experiments were carried out in order to characterize the semiconductor properties of the nanostructured NiO thin films. The experiments were also done for Eosin B- and Erythrosin J-sensitized nanostructured NiO films, with the aim to visualize their potential application as photocatodes in tandem dye-sensitized solar cells (TDSSC). The NiO grown by dipping was the one presenting the best morphological properties. The photoelectrochemical results for all the bare NiO, NiO-Eosin B and NiO-Erythrosin J/electrolyte (I 2 /I - ) systems showed a p-type behavior. An enhancement in the photocurrent has been observed for the systems sensitized with the dyes. For the NiO/Erythrosin J system the enhancement of the current under illumination in comparison to the dark current was about 200%

Improved tribological properties of TiC with porous nanostructured TiO{sub 2} intermediate layer

Energy Technology Data Exchange (ETDEWEB)

Shanaghi, Ali, E-mail: alishanaghi@gmail.com [Surface Engineering Laboratory, Materials Engineering Department, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Ahangarani, Shahrokh, E-mail: sh.ahangarani@gmail.com [Advanced Materials and Renewable Energies Department, Iranian Research Organization for Science and Technology, P.O. Box 15815-3538, Tehran (Iran, Islamic Republic of); Sabour Rouhaghdam, Ali Reza, E-mail: sabour01@modares.ac.ir [Surface Engineering Laboratory, Materials Engineering Department, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Chu, Paul K., E-mail: paul.chu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2011-12-15

Highlights: Black-Right-Pointing-Pointer The porous TiO{sub 2} nanoparticle coating is deposited as an intermediate layer on steel. Black-Right-Pointing-Pointer A homogenous and low friction TiC nanostructure coating is deposited by plasma CVD. Black-Right-Pointing-Pointer Intermediate layer can be determined the nucleation and growth of the TiC coating. Black-Right-Pointing-Pointer The porous interlayer improves the friction and wear of the TiC nanostructure coating. - Abstract: The mismatch in the thermal expansion coefficients between TiC coatings and steel substrates and residual stress in the TiC degrade the tribological properties. In this work, a porous nanostructured TiO{sub 2} coating is deposited as an intermediate layer on hot-work steel (H{sub 11}) before final deposition of the TiC film. This intermediate layer is expected to reduce the interfacial energy, decreases the thermal mismatch between TiC and steel, and improves the tribological properties. Grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and pin-on-disk are used to study the structure as well as tribological properties such as friction, wear, and hardness. Our results reveal that the porous TiO{sub 2} interlayer improves the friction, wear, hardness, and elastic modulus of the system.

Effect of plasma CVD operating temperature on nanomechanical properties of TiC nanostructured coating investigated by atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Shanaghi, Ali, E-mail: alishanaghi@gmail.com [Materials Engineering Department, Faculty of Engineering, Malayer University, P.O. Box: 95863-65719, Malayer (Iran, Islamic Republic of); Rouhaghdam, Ali Reza Sabour, E-mail: sabour01@modares.ac.ir [Surface Engineering Laboratory, Materials Engineering Department, Faculty of Engineering, Tarbiat Modares University, P.O. Box: 14115-143, Tehran (Iran, Islamic Republic of); Ahangarani, Shahrokh, E-mail: sh.ahangarani@gmail.com [Advanced Materials and Renewable Energies Department, Iranian Research Organization for Science and Technology, P.O. Box 15815-3538, Tehran (Iran, Islamic Republic of); Chu, Paul K., E-mail: paul.chu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2012-09-15

Highlights: ► The TiC{sub x} nanostructure coatings have been deposited by PACVD method. ► Dominant mechanism of growth structure at 490 °C is island-layer type. ► TiC{sub x} nanostructure coating applied at 490 °C, exhibits lowest friction coefficient. ► Young's moduli are 289.9, 400 and 187.6 GPa for 470, 490 and 510 °C, respectively. ► This higher elastic modulus and higher hardness of nanocoating obtain at 490 °C. -- Abstract: The structure, composition, and mechanical properties of nanostructured titanium carbide (TiC) coatings deposited on H{sub 11} hot-working tool steel by pulsed-DC plasma assisted chemical vapor deposition at three different temperatures are investigated. Nanoindentation and nanoscratch tests are carried out by atomic force microscopy to determine the mechanical properties such as hardness, elastic modulus, surface roughness, and friction coefficient. The nanostructured TiC coatings prepared at 490 °C exhibit lower friction coefficient (0.23) than the ones deposited at 470 and 510 °C. Increasing the deposition temperature reduces the Young's modulus and hardness. The overall superior mechanical properties such as higher hardness and lower friction coefficient render the coatings deposited at 490 °C suitable for wear resistant applications.

Effect of plasma CVD operating temperature on nanomechanical properties of TiC nanostructured coating investigated by atomic force microscopy

International Nuclear Information System (INIS)

Shanaghi, Ali; Rouhaghdam, Ali Reza Sabour; Ahangarani, Shahrokh; Chu, Paul K.

2012-01-01

Highlights: ► The TiC x nanostructure coatings have been deposited by PACVD method. ► Dominant mechanism of growth structure at 490 °C is island-layer type. ► TiC x nanostructure coating applied at 490 °C, exhibits lowest friction coefficient. ► Young's moduli are 289.9, 400 and 187.6 GPa for 470, 490 and 510 °C, respectively. ► This higher elastic modulus and higher hardness of nanocoating obtain at 490 °C. -- Abstract: The structure, composition, and mechanical properties of nanostructured titanium carbide (TiC) coatings deposited on H 11 hot-working tool steel by pulsed-DC plasma assisted chemical vapor deposition at three different temperatures are investigated. Nanoindentation and nanoscratch tests are carried out by atomic force microscopy to determine the mechanical properties such as hardness, elastic modulus, surface roughness, and friction coefficient. The nanostructured TiC coatings prepared at 490 °C exhibit lower friction coefficient (0.23) than the ones deposited at 470 and 510 °C. Increasing the deposition temperature reduces the Young's modulus and hardness. The overall superior mechanical properties such as higher hardness and lower friction coefficient render the coatings deposited at 490 °C suitable for wear resistant applications.

Use of diluted Ca(OH)2 suspensions and their transformation into nanostructured CaCO3 coatings: A case study in strengthening heritage materials (stucco, adobe and stone)

Science.gov (United States)

Lanzón, Marcos; Madrid, Juan Antonio; Martínez-Arredondo, Ana; Mónaco, Soledad

2017-12-01

In the conservation of heritage materials, the effectiveness of diluted nanolime suspensions in consolidating surfaces is scarcely explored. This paper aims to examine the surface modification of stucco, adobe and stone by deposition of Ca(OH)2 nanoparticles. The nanoparticles were applied in five consecutive coats and transformed into CaCO3 by atmospheric CO2 creating a compatible coating with the surface. The coatings were studied by erosion tests (pull-off tests) and examined by scanning electron microscopy (SEM) and optical microscopy. The tests confirmed the surface resistance was clearly improved due to formation of nanostructured cementing CaCO3 coatings. In addition, the coatings did not practically alter the surface colour due to the diluted nature of the suspensions. To conclude, Ca(OH)2 nanoparticles-based coatings are appropriate solutions to extend the durability of traditional heritage materials, such as stucco, adobe or stone.

Molecular beam epitaxy of three-dimensional Dirac material Sr3PbO

Science.gov (United States)

Samal, D.; Nakamura, H.; Takagi, H.

2016-07-01

A series of anti-perovskites including Sr3PbO are recently predicted to be a three-dimensional Dirac material with a small mass gap, which may be a topological crystalline insulator. Here, we report the epitaxial growth of Sr3PbO thin films on LaAlO3 using molecular beam epitaxy. X-ray diffraction indicates (001) growth of Sr3PbO, where [110] of Sr3PbO matches [100] of LaAlO3. Measurements of the Sr3PbO films with parylene/Al capping layers reveal a metallic conduction with p-type carrier density of ˜1020 cm-3. The successful growth of high quality Sr3PbO film is an important step for the exploration of its unique topological properties.

Ultrasonic-assisted synthesis of nano lead(II) coordination polymer as precursors for preparation of lead(II) oxide nano-structures: Thermal, optical properties and XRD studies.

Science.gov (United States)

Ghavidelaghdam, Elham; Shahverdizadeh, Gholam Hossein; Motameni Tabatabai, Javad; Mirtamizdoust, Babak

2018-04-01

Nano structure of a lead (II) coordination polymer [Pb 2 (C 2 Cl 3 O 2 ) 2 (NO 3 ) 2 (C l2 H 8 N 2 ) 2 ] n (1), has been synthesized by a sonochemical method in different concentrations. The nano particles were characterized by scanning electron microscopy (SEM) X-ray powder diffraction (XRD), FT-IR spectroscopy and elemental analyses. The thermal stability of nano structure is closely investigated via thermal gravimetric (TGA), and compared with crystalline structure. The compounds are then heated to 600 °C to produce PbO nano particles. The resulting PbO is characterized through XRD and SEM analyses. Concentration of initial reagents effects on size and morphology of nano-structured compound 1 have been studied and show that low concentrations of initial reagents decreased particles size and leaded to uniform nano particles morphology. The photoluminescence properties of the prepared compound, as crystalline and as nanoparticles, have been investigated. The result showed a good correlation between the size and emission wavelength. Copyright © 2017. Published by Elsevier B.V.

Effects of atmospheric air plasma treatment on interfacial properties of PBO fiber reinforced composites

Energy Technology Data Exchange (ETDEWEB)

Zhang, Chengshuang, E-mail: cszhang83@163.com; Li, Cuiyun; Wang, Baiya; Wang, Bin; Cui, Hong

2013-07-01

Poly(p-phenylene benzobisoxazole) (PBO) fiber was modified by atmospheric air plasma treatment. The effects of plasma treatment power and speed on both surface properties of PBO fibers and interfacial properties of PBO/epoxy composites were investigated. Surface chemical composition of PBO fibers were analyzed by X-ray photoelectron spectroscopy (XPS). Surface morphologies of the fibers and interface structures of the composites were examined using scanning electron microscopy (SEM). Interfacial adhesion property of the composites was evaluated by interlaminar shear strength (ILSS). Mechanical properties of PBO multifilament were measured by universal testing machine. The results indicate that atmospheric air plasma treatment introduced some polar or oxygen-containing groups to PBO fiber surfaces, enhanced surface roughness and changed surface morphologies of PBO fibers by plasma etching and oxidative reactions. The plasma treatment also improved interfacial adhesion of PBO/epoxy composites but has little effect on tensile properties of PBO multifilament. The ILSS of PBO/epoxy composites increased to 40.0 MPa after atmospheric air plasma treatment with plasma treatment power of 300 W and treatment speed of 6 m/min.

Enhanced interfacial contact between PbS and TiO2 layers in quantum dot solar cells using 2D-arrayed TiO2 hemisphere nanostructures

Science.gov (United States)

Lee, Wonseok; Ryu, Ilhwan; Lee, Haein; Yim, Sanggyu

2018-02-01

Two-dimensionally (2D) arrayed hemispherical nanostructures of TiO2 thin films were successfully fabricated using a simple procedure of spin-coating or dip-coating TiO2 nanoparticles onto 2D close-packed polystyrene (PS) nanospheres, followed by PS extraction. The nanostructured TiO2 film was then used as an n-type layer in a lead sulfide (PbS) colloidal quantum dot solar cell. The TiO2 nanostructure could provide significantly increased contacts with subsequently deposited PbS quantum dot layer. In addition, the periodically arrayed nanostructure could enhance optical absorption of the cell by redirecting the path of the incident light and increasing the path length passing though the active layer. As a result, the power conversion efficiency (PCE) reached 5.13%, which is approximately a 1.7-fold increase over that of the control cell without nanostructuring, 3.02%. This PCE enhancement can mainly be attributed to the increase of the short-circuit current density from 19.6 mA/cm2 to 30.6 mA/cm2, whereas the open-circuit voltage and fill factor values did not vary significantly.

Microstructure and Tribological Performance of TiB2-NiCr Composite Coating Deposited by APS

Directory of Open Access Journals (Sweden)

Ning Zhang

2017-12-01

Full Text Available Nickel chromium (NiCr powders with different titanium diboride (TiB2 additions (20, 40 and 60 wt % were prepared with a mechanical alloying method and then sprayed using an air plasma spraying technology. The microstructure and phase composite of the powders and the cross-sections of deposited coatings were analyzed with a scanning electronic microscope and X-ray diffraction. The tribological performance of the coatings was studied using a pin-on-disk tribometer at room temperature. The weight loss of the as-sprayed coating was measured by using a high accuracy weighing balance. Cr3C2-25NiCr coating was produced and tested for comparison. The morphologies of the worn surface were then investigated. Parts of debris with some scratches were found, presenting typical signs of abrasive wear and showing slight adhesive wear on the surface. The 20 wt % additive TiB2 coating demonstrated the highest microhardness and the lowest coefficient of friction. The wear resistance of the metal-ceramic composites coatings was enhanced with the addition of TiB2.

Dielectric and electrical conductivity studies of bulk lead (II) oxide (PbO)

Energy Technology Data Exchange (ETDEWEB)

Darwish, A.A.A., E-mail: aaadarwish@gmail.com [Department of Physics, Faculty of Education at Al-Mahweet, Sana’a University, Al-Mahwit (Yemen); Department of Physics, Faculty of Science, University of Tabuk, P.O. Box 741, Tabuk 71491, Tabuk (Saudi Arabia); El-Zaidia, E.F.M.; El-Nahass, M.M. [Department of Physics, Faculty of Education, Ain Shams University, Rorxy, Cairo 11757 (Egypt); Hanafy, T.A. [Department of Physics, Faculty of Science, University of Tabuk, P.O. Box 741, Tabuk 71491, Tabuk (Saudi Arabia); Department of Physics, Faculty of Science, Fayoum University, 63514 El Fayoum (Egypt); Al-Zubaidi, A.A. [Department of Physics, Faculty of Science, University of Tabuk, P.O. Box 741, Tabuk 71491, Tabuk (Saudi Arabia)

2014-03-15

Highlights: • The AC measurements of PbO were measured at temperature range 313–523 K. • The dielectric constants increased with temperature. • The mechanism responsible for AC conduction is electronic hopping. -- Abstract: The dielectric properties, the impedance spectroscopy and AC conductivity of bulk PbO have been investigated as a function of frequency and temperature. The measurements were carried out in the frequency range from 40 to 5 × 10{sup 6} Hz and in temperature range from 313 to 523 K. The frequency response of dielectric constant, ε{sub 1}, and dielectric loss index, ε{sub 2}, as a function of temperature were studied. The values of ε{sub 1} and ε{sub 2} were found to decrease with the increase in frequency. However, they increase with the increase in temperature. The presence of a single arc in the complex modulus spectrum at different temperatures confirms the single-phase character of the PbO. The AC conductivity exhibited a universal dynamic response: σ{sub AC} = Aω{sup s}. The AC conductivity was also found to increase with increasing temperature and frequency. The correlation barrier hopping (CBH) model was found to apply to the AC conductivity data. The calculated values of s were decreased with temperature. This behavior reveals that the conduction mechanism for PbO samples is CBH. The activation energy for AC conductivity decreases with increasing frequency. This confirms that the hopping conduction to the dominant mechanism for PbO samples.

Superhydrophobic Bilayer Coating Based on Annealed Electrospun Ultrathin Poly(ε-caprolactone Fibers and Electrosprayed Nanostructured Silica Microparticles for Easy Emptying Packaging Applications

Directory of Open Access Journals (Sweden)

Juliana Lasprilla-Botero

2018-05-01

Full Text Available A coating rendering superhydrophobic properties to low-density polyethylene (LDPE films used in packaging applications was herein generated by means of the electrohydrodynamic processing (EHDP technique. To this end, electrospun ultrathin poly(ε-caprolactone (PCL fibers, followed by electrosprayed nanostructured silica (SiO2 microparticles, were deposited on top of the LDPE film. Various electrospinning and electrospraying times were tested and optimized followed by a thermal post-treatment to provide physical adhesion between the bilayer coating and the LDPE substrate. The morphology, hydrophobicity, permeance to limonene, and thermal stability of the resultant nanostructured coatings were characterized. It was observed that by controlling both the deposition time of the electrospun ultrathin PCL fibers and the electrosprayed SiO2 microparticles, as well as the conditions of the thermal post-treatment, effective superhydrophobic coatings were developed onto the LDPE films. The resultant multilayer presented a hierarchical micro/nanostructured surface with an apparent contact angle of 157° and a sliding angle of 8°. The addition of silica reduced, to some extent, the limonene (aroma barrier, likely due to the increased surface-to-volume ratio, which allowed permeant sorption to occur but improved the thermal stability of the LDPE/PCL film. As a result, the developed multilayer system of LDPE/PCL/SiO2 has significant potential for use in easy-to-empty packaging applications of high water activity products.

In situ fabrication of nanostructured titania coating on the surface of titanium wire: A new approach for preparation of solid-phase microextraction fiber

International Nuclear Information System (INIS)

Cao Dandan; Lue Jianxia; Liu Jingfu; Jiang Guibin

2008-01-01

Nanostructured titania-based solid-phase microextraction (SPME) fibers were fabricated through the in situ oxidation of titanium wires with H 2 O 2 (30%, w/w) at 80 deg. C for 24 h. The obtained SPME fibers possess a ∼1.2 μm thick nanostructured coating consisting of ∼100 nm titania walls and 100-200 nm pores. The use of these fibers for headspace SPME coupled with gas chromatography with electron capture detection (GC-ECD) resulted in improved analysis of dichlorodiphenyltrichloroethane (DDT) and its degradation products. The presented method to detect DDT and its degradation products has high sensitivity (0.20-0.98 ng L -1 ), high precision (relative standard deviation R.S.D. = 9.4-16%, n = 5), a wide linear range (5-5000 ng L -1 ), and good linearity (coefficient of estimation R 2 = 0.991-0.998). As the nanostructured titania was in situ formed on the surface of a titanium wire, the coating was uniformly and strongly adhered on the titanium wire. Because of the inherent chemical stability of the titania coating and the mechanical durability of the titanium wire substrate, this new SPME fiber exhibited long life span (over 150 times)

Structural transformations of TiO{sub 2} films with deposition temperature and electrical properties of nanostructure n-TiO{sub 2}/p-Si heterojunction diode

Energy Technology Data Exchange (ETDEWEB)

Aksoy, Seval; Caglar, Yasemin, E-mail: yasemincaglar@anadolu.edu.tr

2014-11-15

Highlights: • Titanium oxide (TiO{sub 2}) films have been deposited on p-Si substrates by sol gel spin coating technique. • The effect of deposition temperatures on structural and morphological properties of TiO{sub 2} films. • The electrical parameters of nanostructure n-TiO{sub 2}/p-Si heterojunction diode such as n, R{sub s} and ϕ{sub b} were investigated. - Abstract: Titanium oxide (TiO{sub 2}) films have been deposited on p-Si substrates by sol–gel method using spin coating technique. Structural and morphological properties were studied as a function of deposition temperatures by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The deposition temperatures were chosen from 700 °C to 1100 °C. Crystallization of the anatase phase and its transformation to the rutile phase were observed at 700 °C and 800 °C, respectively. The fabrication of nanostructure n-TiO{sub 2}/p-Si heterojunction diode was formed by using T7 film deposited at 700 °C. The electrical parameters such as barrier height (ϕ{sub b}) and ideality factor (n) of nanostructure n-TiO{sub 2}/p-Si heterojunction diode were investigated by using I–V measurements and observed to be 0.58 eV and 5.39, respectively. Also, the values of ϕ{sub b} and series resistance (R{sub s}) were determined by using Cheung’s and Norde methods. From the I–V measurements taken at room temperature, the space charge limited (SCLC) mechanism was determined at the low voltage region. The obtained results showed that n-TiO{sub 2}/p-Si heterojunction diode is a good candidate for the applications of semiconductor electronic devices.

Electrospark deposition of Al2O3–TiB2/Ni composite-phase surface coatings on Cu–Cr–Zr alloy electrodes

Directory of Open Access Journals (Sweden)

Ping Luo

2015-03-01

Full Text Available To improve electrode life during the resistance spot welding of galvanized steel plates, an Al2O3–TiB2 composite coating was synthesized on the surfaces of spot-welding electrodes through an electrospark deposition process. The microstructure, elemental composition, phase structure, and mechanical properties of the coating were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, and microhardness testing. It was found that extensive cracking occurred in the monolithic Al2O3–TiB2 coating and at the coating–electrode interface. When the Al2O3–TiB2 coating was deposited on electrodes precoated with Ni, the number of defects decreased significantly. Further, delamination did not occur, and fewer cracks were formed. The average hardness of the multilayered Al2O3–TiB2/Ni coating was approximately 2200 HV and higher than that of the monolithic Al2O3–TiB2 coating (1100 HV.

Au-coated 3-D nanoporous titania layer prepared using polystyrene-b-poly(2-vinylpyridine) block copolymer nanoparticles.

Science.gov (United States)

Shin, Won-Jeong; Basarir, Fevzihan; Yoon, Tae-Ho; Lee, Jae-Suk

2009-04-09

New nanoporous structures of Au-coated titania layers were prepared by using amphiphilic block copolymer nanoparticles as a template. A 3-D template composed of self-assembled quaternized polystyrene-b-poly(2-vinylpyridine) (Q-PS-b-P2VP) block copolymer nanoparticles below 100 nm was prepared. The core-shell-type nanoparticles were well ordered three-dimensionally using the vertical immersion method on the substrate. The polar solvents were added to the polymer solution to prevent particle merging at 40 degrees C when considering the interaction between polymer nanoparticles and solvents. Furthermore, Au-coated PS-b-P2VP nanoparticles were prepared using thiol-capped Au nanoparticles (3 nm). The 3-D arrays with Au-coated PS-b-P2VP nanoparticles as a template contributed to the preparation of the nanoporous Au-coated titania layer. Therefore, the nanoporous Au-coated titania layer was fabricated by removing PS-b-P2VP block copolymer nanoparticles by oxygen plasma etching.

A biodegradable AZ91 magnesium alloy coated with a thin nanostructured hydroxyapatite for improving the corrosion resistance

Energy Technology Data Exchange (ETDEWEB)

Mukhametkaliyev, T.M.; Surmeneva, M.A. [National Research Tomsk Polytechnic University, 634050, Lenin Avenue 43, Tomsk (Russian Federation); Vladescu, A. [National Research Tomsk Polytechnic University, 634050, Lenin Avenue 43, Tomsk (Russian Federation); National Institute for Optoelectronics, 409 Atomistilor St., RO77125 Magurele (Romania); Cotrut, C.M. [National Research Tomsk Polytechnic University, 634050, Lenin Avenue 43, Tomsk (Russian Federation); Politehnica University of Bucharest, 313 Spl. Independentei, Bucharest (Romania); Braic, M.; Dinu, M. [National Institute for Optoelectronics, 409 Atomistilor St., RO77125 Magurele (Romania); Vranceanu, M.D. [Politehnica University of Bucharest, 313 Spl. Independentei, Bucharest (Romania); Pana, I. [National Institute for Optoelectronics, 409 Atomistilor St., RO77125 Magurele (Romania); Faculty of Physics, Bucharest University, 405 Atomistilor St., RO77125 Magurele (Romania); Mueller, M. [Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, 70569 Stuttgart (Germany); Surmenev, R.A., E-mail: rsurmenev@gmail.com [National Research Tomsk Polytechnic University, 634050, Lenin Avenue 43, Tomsk (Russian Federation)

2017-06-01

The main aim of this study was to investigate the properties of an AZ91 alloy coated with nanostructured hydroxyapatite (HA) prepared by radio frequency (RF) magnetron sputtering. The bioactivity and biomineralization of the AZ91 magnesium alloy coated with HA were investigated in simulated body fluid (SBF) via an in vitro test. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) analyses were performed. The samples were immersed in SBF to study the ability of the surface to promote the formation of an apatite layer as well as corrosion resistance and mass change of the HA-coated AZ91 alloy. Electrochemical tests were performed to estimate the corrosion behaviour of HA-coated and uncoated samples. The results revealed the capability of the HA coating to significantly improve the corrosion resistance of the uncoated AZ91 alloy. - Highlights: • The nanostructured HA layer allows to control the degradation rate of the AZ91 alloy. • The HA coating significantly reduces the corrosion current density. • The HA coating significantly improves the polarization resistance in vitro. • The RF magnetron deposited HA coating promotes calcium-phosphate precipitation in SBF.

A biodegradable AZ91 magnesium alloy coated with a thin nanostructured hydroxyapatite for improving the corrosion resistance

International Nuclear Information System (INIS)

Mukhametkaliyev, T.M.; Surmeneva, M.A.; Vladescu, A.; Cotrut, C.M.; Braic, M.; Dinu, M.; Vranceanu, M.D.; Pana, I.; Mueller, M.; Surmenev, R.A.

2017-01-01

The main aim of this study was to investigate the properties of an AZ91 alloy coated with nanostructured hydroxyapatite (HA) prepared by radio frequency (RF) magnetron sputtering. The bioactivity and biomineralization of the AZ91 magnesium alloy coated with HA were investigated in simulated body fluid (SBF) via an in vitro test. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) analyses were performed. The samples were immersed in SBF to study the ability of the surface to promote the formation of an apatite layer as well as corrosion resistance and mass change of the HA-coated AZ91 alloy. Electrochemical tests were performed to estimate the corrosion behaviour of HA-coated and uncoated samples. The results revealed the capability of the HA coating to significantly improve the corrosion resistance of the uncoated AZ91 alloy. - Highlights: • The nanostructured HA layer allows to control the degradation rate of the AZ91 alloy. • The HA coating significantly reduces the corrosion current density. • The HA coating significantly improves the polarization resistance in vitro. • The RF magnetron deposited HA coating promotes calcium-phosphate precipitation in SBF.

Morphological and microstructural characterization of nanostructured pure α-phase W coatings on a wide thickness range

Energy Technology Data Exchange (ETDEWEB)

Gordillo, N., E-mail: nuri.gordillo@gmail.com [Instituto de Fusión Nuclear, ETSI de Industriales, Universidad Politécnica de Madrid, C/José Gutierrez Abascal, 2, E-28006 Madrid (Spain); CEI Campus Moncloa, UCM-UPM, Madrid (Spain); Panizo-Laiz, M. [Instituto de Fusión Nuclear, ETSI de Industriales, Universidad Politécnica de Madrid, C/José Gutierrez Abascal, 2, E-28006 Madrid (Spain); Tejado, E. [Department of Materials Science, Research Centre on Safety and Durability of Structures and Materials (CISDEM), UPM-CSIC, C/Profesor Aranguren s/n, E-28040 Madrid (Spain); Centro Nacional de Investigaciones Metalúrgicas, CENIM-CSIC, Madrid (Spain); Fernandez-Martinez, I. [Instituto de Energía Solar (IES), Universidad Politécnica de Madrid, Avenida Complutense s/n, E-28040 Madrid (Spain); Instituto de Microelectrónica de Madrid, IMM-CNM-CSIC, Isaac Newton 8 PTM, Tres Cantos, E-28760 Madrid (Spain); Rivera, A. [Instituto de Fusión Nuclear, ETSI de Industriales, Universidad Politécnica de Madrid, C/José Gutierrez Abascal, 2, E-28006 Madrid (Spain); Pastor, J.Y. [Department of Materials Science, Research Centre on Safety and Durability of Structures and Materials (CISDEM), UPM-CSIC, C/Profesor Aranguren s/n, E-28040 Madrid (Spain); Castro, C. Gómez de [Departamento de Física de Materiales, Facultad de CC. Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, E-28040 Madrid (Spain); and others

2014-10-15

Highlights: • Pure α-phase tungsten nanostructures were deposited by DC-magnetron sputtering. • Non-delaminated coatings were achieved at powers ≤50 W. • The coating thicknesses vary from 30 nm up to ∼4.0 μm. • The influence of the substrate on the coating properties was investigated. • We report on the morphological, microstructural and mechanical properties. - Abstract: Nanostructured tungsten (nanoW) coatings have been deposited by DC magnetron sputtering. First, the influence of the sputtering power on the adhesion of the coatings to the substrate was investigated by depositing coatings at powers varying from 30 up to 220 W. Non-delaminated coatings were achieved at powers ≤50 W. Second, the influence of coating thickness on the morphological, microstructural and mechanical properties was investigated for films deposited at 50 W with thicknesses varying from 30 nm up to ∼4.0 μm. SEM images reveal that all the films are highly compact, consisting of nanometer sized columns that grow perpendicular to the substrate. XRD data evidence that films are monophasic, being made of pure α-phase. All coatings show compressive stress and low micro-strain. Nanoindentation tests show that coatings have a hardness higher than that reported for coarse grained W. No significant dependence of the previous properties on coating thickness was observed. Finally, the influence of the substrate on coatings properties was studied, by depositing a W coating at a power of 50 W on a commercial steel substrate: no significant dependence was found.

Effects of nanostructured, diamondlike, carbon coating and nitrocarburizing on the frictional properties and biocompatibility of orthodontic stainless steel wires.

Science.gov (United States)

Zhang, Hao; Guo, Shuyu; Wang, Dongyue; Zhou, Tingting; Wang, Lin; Ma, Junqing

2016-09-01

To evaluate and compare the effects of nanostructured, diamondlike, carbon (DLC) coating and nitrocarburizing on the frictional properties and biocompatibility of orthodontic stainless steel archwires. Plasma-enhanced chemical vapor deposition technology was applied to coat DLC films onto the surface of austenitic stainless steel wires, and salt-bath nitrocarburizing technology was employed to achieve surface hardening of other wires. Surface and cross-sectional characteristics, microhardness, modulus of elasticity, friction resistance, corrosion resistance, and cell toxicity of the modified and control wires were analyzed. The surfaces of the DLC-coated and nitrocarburized wires were both smooth and even. Compared with the control, the DLC-coated wires were increased in surface hardness 1.46 times, decreased in elastic modulus, reduced in kinetic friction coefficient by 40.71%, and decreased in corrosion current density by two orders of magnitude. The nitrocarburized wire was increased in surface hardness 2.39 times, exhibited an unchanged elastic modulus, demonstrated a decrease in maximum static friction force of 22.2%, and rose in corrosion current density two orders of magnitude. Cytotoxicity tests revealed no significant toxicity associated with the modified wires. DLC coating and nitrocarburizing significantly improved the surface hardness of the wires, reduced friction, and exhibited good biocompatibility. The nanostructured DLC coating provided excellent corrosion resistance and good elasticity, and while the nitrocarburizing technique substantially improved frictional properties, it reduced the corrosion resistance of the stainless steel wires to a lesser extent.

Fabricating ordered functional nanostructures onto polycrystalline substrates from the bottom-up

International Nuclear Information System (INIS)

Torres, María; Pardo, Lorena; Ricote, Jesús; Fuentes-Cobas, Luís E.; Rodriguez, Brian J.; Calzada, M. Lourdes

2012-01-01

Microemulsion-mediated synthesis has emerged as a powerful bottom-up procedure for the preparation of ferroelectric nanostructures onto substrates. However, periodical order has yet to be achieved onto polycrystalline Pt-coated Si substrates. Here, we report a new methodology that involves microemulsion-mediated synthesis and the controlled modification of the surface of the substrate by coating it with a template-layer of water-micelles. This layer modifies the surface tension of the substrate and yields a periodic arrangement of ferroelectric crystalline nanostructures. The size of the nanostructures is decreased to the sub-50 nm range and they show a hexagonal order up to the third neighbors, which corresponds to a density of 275 Gb in −2 . The structural analysis of the nanostructures by synchrotron X-ray diffraction confirms that the nanostructures have a PbTiO 3 perovskite structure, with lattice parameters of a = b = 3.890(0) Å and c = 4.056(7) Å. Piezoresponse force microscopy confirmed the ferro-piezoelectric character of the nanostructures. This simple methodology is valid for the self-assembly of other functional oxides onto polycrystalline substrates, enabling their reliable integration into micro/nano devices.

Lead Oxide- PbO Humidity Sensor

Directory of Open Access Journals (Sweden)

Sk. Khadeer Pasha

2010-11-01

Full Text Available Alcohol thermal route has been used to synthesize nanocrystalline PbO at a low temperature of 75 oC using lead acetate. The synthesized PbO (P75 was annealed in the temperatures ranging from 200-500 oC for 2 h to study the effect of crystal structure and phase changes and were labeled as P200, P300, P400 and P500, respectively. X-Ray diffraction and FT-IR spectroscopy were carried out to identify the structural phases and vibrational stretching frequencies respectively. The TEM images revealed the porous nature of P75 sample which is an important criterion for the humidity sensor. The dc resistance measurements were carried out in the relative humidity (RH range 5-98 %. Among the different prepared, P75 possessed the highest humidity sensitivity of 6250, while the heat treated sample P500 have a low sensitivity of 330. The response and recovery characteristics of the maximum sensitivity sample P75 were 170 s and 40 s respectively.

Increasing the stability of DNA nanostructure templates by atomic layer deposition of Al2O3 and its application in imprinting lithography

Directory of Open Access Journals (Sweden)

Hyojeong Kim

2017-11-01

Full Text Available We present a method to increase the stability of DNA nanostructure templates through conformal coating with a nanometer-thin protective inorganic oxide layer created using atomic layer deposition (ALD. DNA nanotubes and origami triangles were coated with ca. 2 nm to ca. 20 nm of Al2O3. Nanoscale features of the DNA nanostructures were preserved after the ALD coating and the patterns are resistive to UV/O3 oxidation. The ALD-coated DNA templates were used for a direct pattern transfer to poly(L-lactic acid films.

Application of Nano-Structured Coatings for Mitigation of Flow-Accelerated Corrosion in Secondary Pipe Systems of Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Kim, Seung Hyun; Kim, Jong Jin; Yoo, Seung Chang; Huh, Jae Hoon; Kim, Ji Hyun [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

2014-05-15

Flow-accelerated corrosion (FAC) is a complex corrosion process combined with mechanical reaction with fluid. There were lots of research to mitigate FAC such as controlling temperature or water chemistry but in this research, we adopt active coating techniques especially nano-particle reinforced coatings. One of the general characteristics of FAC and its mitigation is that surface friction due to surface morphology makes a significant effect on FAC. Therefore to form a uniform coating layers, nano-particles including TiO2, SiC, Fe-Cr-W and Graphene were utilized. Those materials are known as greatly improve the corrosion resistance of substrates such as carbon steels but their effects on mitigation of FAC are not revealed clearly. Therefore in this research, the FAC resistive performance of nano-structured coatings were tested by electrochemical impedance spectroscopy (EIS) in room temperature 15 wt% sulfuric acid. As the flow-accelerated corrosion inhibitors in secondary piping system of nuclear power plants, various kinds of nano-structured coatings were prepared and tested in room-temperature electrochemical cells. SHS7740 with two types of Densifiers, electroless nickel plating with TiO2 are prepared. Electropolarization curves shows the outstanding corrosion mitigation performance of SHS7740 but EIS results shows the promising potential of Ni-P and Ni-P-TiO2 electroless nickel plating. For future work, high-temperature electrochemical analysis system will be constructed and in secondary water chemistry will be simulated.

Multistep structural transition of hydrogen trititanate nanotubes into TiO2-B nanotubes: a comparison study between nanostructured and bulk materials

International Nuclear Information System (INIS)

Morgado, Edisson Jr; Jardim, P M; Marinkovic, Bojan A; Rizzo, Fernando C; Abreu, Marco A S de; Zotin, Jose L; Araujo, Antonio S

2007-01-01

H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO 2 followed by proton exchange were compared to their bulk H 2 Ti 3 O 7 counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H 2 Ti 3 O 7 nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H 2 Ti 3 O 7 converts into TiO 2 (B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 deg. C through topotactic mechanisms with the intermediate formation of nanostructured H 2 Ti 6 O 13 and H 2 Ti 12 O 25 , which are more condensed layered titanates eventually rearranging to TiO 2 (B). Our results suggest that the intermediate tunnel structure H 2 Ti 12 O 25 is the final layered intermediate phase, on which TiO 2 (B) nucleates and grows. The conversion of nanostructured TiO 2 (B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology

Multistep structural transition of hydrogen trititanate nanotubes into TiO2-B nanotubes: a comparison study between nanostructured and bulk materials.

Science.gov (United States)

Morgado, Edisson; Jardim, P M; Marinkovic, Bojan A; Rizzo, Fernando C; de Abreu, Marco A S; Zotin, José L; Araújo, Antonio S

2007-12-12

H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO(2) followed by proton exchange were compared to their bulk H(2)Ti(3)O(7) counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H(2)Ti(3)O(7) nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H(2)Ti(3)O(7) converts into TiO(2)(B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 degrees C through topotactic mechanisms with the intermediate formation of nanostructured H(2)Ti(6)O(13) and H(2)Ti(12)O(25), which are more condensed layered titanates eventually rearranging to TiO(2)(B). Our results suggest that the intermediate tunnel structure H(2)Ti(12)O(25) is the final layered intermediate phase, on which TiO(2)(B) nucleates and grows. The conversion of nanostructured TiO(2)(B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology.

Multistep structural transition of hydrogen trititanate nanotubes into TiO2-B nanotubes: a comparison study between nanostructured and bulk materials

Science.gov (United States)

Morgado, Edisson, Jr.; Jardim, P. M.; Marinkovic, Bojan A.; Rizzo, Fernando C.; de Abreu, Marco A. S.; Zotin, José L.; Araújo, Antonio S.

2007-12-01

H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO2 followed by proton exchange were compared to their bulk H2Ti3O7 counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H2Ti3O7 nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H2Ti3O7 converts into TiO2(B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 °C through topotactic mechanisms with the intermediate formation of nanostructured H2Ti6O13 and H2Ti12O25, which are more condensed layered titanates eventually rearranging to TiO2(B). Our results suggest that the intermediate tunnel structure H2Ti12O25 is the final layered intermediate phase, on which TiO2(B) nucleates and grows. The conversion of nanostructured TiO2(B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology.

Near zero reflection by nanostructured anti-reflection coating design for Si substrates

Science.gov (United States)

Al-Fandi, Mohamed; Makableh, Yahia F.; Khasawneh, Mohammad; Rabady, Rabi

2018-05-01

The nanostructure design of near zero reflection coating for Si substrates by using ZnO Nanoneedles (ZnONN) is performed and optimized for the visible spectral range. The design investigates the ZnONN tip to body ratio effect on the anti-reflection coating properties. Different tip to body ratios are used on Si substrates. Around zero reflection is achieved by the Nanoneedles structure design presented in this work, leading to minimal reflection losses from the Si surface. The current design evolves a solution to optical losses and surface contamination effects associated with Si solar cells.

In situ fabrication of nanostructured titania coating on the surface of titanium wire: A new approach for preparation of solid-phase microextraction fiber

Energy Technology Data Exchange (ETDEWEB)

Cao Dandan [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Environmental Science Division, School of Earth and Space Science, University of Science and Technology of China, Hefei, Anhui Province 230026 (China); Lue Jianxia [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Liu Jingfu [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)], E-mail: jfliu@rcees.ac.cn; Jiang Guibin [State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)

2008-03-17

Nanostructured titania-based solid-phase microextraction (SPME) fibers were fabricated through the in situ oxidation of titanium wires with H{sub 2}O{sub 2} (30%, w/w) at 80 deg. C for 24 h. The obtained SPME fibers possess a {approx}1.2 {mu}m thick nanostructured coating consisting of {approx}100 nm titania walls and 100-200 nm pores. The use of these fibers for headspace SPME coupled with gas chromatography with electron capture detection (GC-ECD) resulted in improved analysis of dichlorodiphenyltrichloroethane (DDT) and its degradation products. The presented method to detect DDT and its degradation products has high sensitivity (0.20-0.98 ng L{sup -1}), high precision (relative standard deviation R.S.D. = 9.4-16%, n = 5), a wide linear range (5-5000 ng L{sup -1}), and good linearity (coefficient of estimation R{sup 2} = 0.991-0.998). As the nanostructured titania was in situ formed on the surface of a titanium wire, the coating was uniformly and strongly adhered on the titanium wire. Because of the inherent chemical stability of the titania coating and the mechanical durability of the titanium wire substrate, this new SPME fiber exhibited long life span (over 150 times)

Nanostructured and nanolayer coatings based on nitrides of the metals structure study and structure and composition standard samples set development

Directory of Open Access Journals (Sweden)

E. B. Chabina

2014-01-01

Full Text Available Researches by methods of analytical microscopy and the x-ray analysis have allowed to develop a set of standard samples of composition and structure of the strengthening nanostructured and nanolayer coatings for control of the strengthening nanostructured and nanolayer coatings based on nitrides of the metals used to protect critical parts of the compressor of the gas turbine engine from dust erosion, corrosion and oxidation.

Osseointegration is improved by coating titanium implants with a nanostructured thin film with titanium carbide and titanium oxides clustered around graphitic carbon

International Nuclear Information System (INIS)

Veronesi, Francesca; Giavaresi, Gianluca; Fini, Milena; Longo, Giovanni; Ioannidu, Caterina Alexandra; Scotto d'Abusco, Anna; Superti, Fabiana; Panzini, Gianluca; Misiano, Carlo; Palattella, Alberto; Selleri, Paolo; Di Girolamo, Nicola; Garbarino, Viola; Politi, Laura; Scandurra, Roberto

2017-01-01

Titanium implants coated with a 500 nm nanostructured layer, deposited by the Ion Plating Plasma Assisted (IPPA) technology, composed of 60% graphitic carbon, 25% titanium oxides and 15% titanium carbide were implanted into rabbit femurs whilst into the controlateral femurs uncoated titanium implants were inserted as control. At four time points the animals were injected with calcein green, xylenol orange, oxytetracycline and alizarin. After 2, 4 and 8 weeks femurs were removed and processed for histology and static and dynamic histomorphometry for undecalcified bone processing into methylmethacrylate, sectioned, thinned, polished and stained with Toluidine blue and Fast green. The overall bone-implant contacts rate (percentage of bone-implant contacts/weeks) of the TiC coated implant was 1.6 fold than that of the uncoated titanium implant. The histomorphometric analyses confirmed the histological evaluations. More precisely, higher Mineral Apposition Rate (MAR, μm/day) (p < 0.005) and Bone Formation Rate (BFR, μm 2 /μm/day) (p < 0.0005) as well as Bone Implant Contact (Bic) and Bone Ingrowth values (p < 0.0005) were observed for the TiC coated implants compared to uncoated implants. In conclusion the hard nanostructured TiC layer protects the bulk titanium implant against the harsh conditions of biological tissues and in the same time, stimulating adhesion, proliferation and activity of osteoblasts, induces a better bone-implant contacts of the implant compared to the uncoated titanium implant. - Highlights: • Ti implants were coated with a nanostructured film composed of C gr , TiC and TiO x . • The TiC layer stimulates adhesion, proliferation and activity of osteoblasts. • Uncoated and TiC coated titanium implants were implanted in rabbit femurs. • Bone-implant contacts of TiC coated implants were higher than that of uncoated. • Mineral Apposition Rate of TiC coated implants were higher than that of uncoated.

In vivo study of nanostructured diopside (CaMgSi2O6) coating on magnesium alloy as biodegradable orthopedic implants

International Nuclear Information System (INIS)

Razavi, Mehdi; Fathi, Mohammadhossein; Savabi, Omid; Razavi, Seyed Mohammad; Heidari, Fariba; Manshaei, Maziar; Vashaee, Daryoosh; Tayebi, Lobat

2014-01-01

Highlights: • In vitro biocompatibility of biodegradable Mg alloy was improved by diopside coating. • In vivo biocompatibility of biodegradable Mg alloy was improved by diopside coating. • Degradation behavior of biodegradable Mg alloy was improved by diopside coating. - Abstract: In order to improve the corrosion resistance and bioactivity of a biodegradable magnesium alloy, we have recently prepared a nanostructured diopside (CaMgSi 2 O 6 ) coating on AZ91 magnesium alloy through a combined micro-arc oxidation (MAO) and electrophoretic deposition (EPD) method (reported elsewhere). In this work, we performed a detailed biocompatibility analysis of the implants made by this material and compared their performance with those of the uncoated and micro arc oxidized magnesium implants. The biocompatibility evaluation of samples was performed by culturing L-929 cells and in vivo animal study, including implantation of samples in greater trochanter of rabbits, radiography and histological examinations. The results from both the in vitro and in vivo studies indicated that the diopside/MAO coated magnesium implant significantly enhanced cell viability, biodegradation resistance and new bone formation compared with both the uncoated and the micro-arc oxidized magnesium implants. Our data provides an example of how the proper surface treatment of magnesium implants can overcome their drawbacks in terms of high degradation rate and gas bubble formation under physiological conditions

Electrochemical impedance spectroscopy and corrosion behaviour of Al2O3-Ni nano composite coatings

International Nuclear Information System (INIS)

Ciubotariu, Alina-Crina; Benea, Lidia; Lakatos-Varsanyi, Magda; Dragan, Viorel

2008-01-01

In this paper, the results on the electrochemical impedance spectroscopy and corrosion properties of electrodeposited nanostructured Al 2 O 3 -Ni composite coatings are presented. The nanocomposite coatings were obtained by codeposition of alumina nanoparticles (13 nm) with nickel during plating process. The coating thickness was 50 μm on steel support and an average of nano Al 2 O 3 particles inside of coatings at 15 vol.% was present. The structure of the coatings was investigated by scanning electron microscopy (SEM). It has been found that the codeposition of Al 2 O 3 particles with nickel disturbs the nickel coating's regular surface structure. The electrochemical behavior of the coatings in the corrosive solutions was investigated by polarization potentiodynamic and electrochemical impedance spectroscopy methods. As electrochemical test solutions 0.5 M sodium chloride and 0.5 M potassium sulphate were used in a three electrode open cell. The corrosion potential is shifted to more negative values for nanostructured coatings in 0.5 M sodium chloride. The polarization resistance in 0.5 M sodium chloride decreases in 24 h, but after that increases slowly. In 0.5 M potassium sulphate solution the polarization resistance decreases after 2 h and after 30 h of immersion the polarization resistance is higher than that of the beginning value. The corrosion rate calculated by polarization potentiodynamic curves obtained after 30 min from immersion in solution is smaller for nanostructured coatings in 0.5 M potassium sulphate (4.74 μm/year) and a little bit bigger in 0.5 M sodium chloride (5.03 μm/year)

Nano-structure TiO2 film coating on 316L stainless steel via sol-gel technique for blood compatibility improvement

Directory of Open Access Journals (Sweden)

Mohammadreza Foruzanmehr

2014-04-01

Full Text Available   Objective(s: Titanium oxides are known to be appropriate hemocompatible materials which are suggested as coatings for blood-contacting devices. Little is known about the influence of nanometric crystal structure, layer thickness, and semiconducting characteristics of TiO2 on blood hemostasis.   Materials and Methods: Having used sol-gel dip coating method in this study, TiO2 thin films were deposited on nano-scale electro-polished stainless steel 316L with 1 to 5 nano-sized layers. Surface morphology and structure of the film were studied with X-ray diffraction and atomic force microscopy. Blood compatibility was also determined by measuring the platelet activation (CD62P expression, platelet adhesion (Scanning Electron Microscopy, and the blood clotting time on these samples. Results: The films were compact and smooth and existed mainly in the form of anatase. By increasing the number of TiO2 thin layer, clotting time greatly extended, and the population of activated platelet and P-selectine expression changed according to the surface characteristics of each layer. Conclusion: The findings revealed that stainless steel 316L coated with nano-structured TiO2 layer improved blood compatibility, in terms of both blood platelet activity and coagulation cascade, which can decrease the thrombogenicity of blood contacting devices which were made from stainless steel.

Effects of PbO on the oxide films of incoloy 800HT in simulated primary circuit of PWR

International Nuclear Information System (INIS)

Tan, Yu; Yang, Junhan; Wang, Wanwan; Shi, Rongxue; Liang, Kexin; Zhang, Shenghan

2016-01-01

Effects of trace PbO on oxide films of Incoloy 800HT were investigated in simulated primary circuit water chemistry of PWR, also with proper Co addition. The trace PbO addition in high temperature water blocked the protective spinel oxides formation of the oxide films of Incoloy 800HT. XPS results indicated that the lead, added as PbO into the high temperature water, shows not only +2 valance but also +4 and 0 valances in the oxide film of 800HT co-operated with Fe, Cr and Ni to form oxides films. Potentiodynamic polarization results indicated that as PbO concentration increased, the current densities of the less protective oxide films of Incoloy 800HT decreased in a buffer solution tested at room temperature. The capacitance results indicated that the donor densities of oxidation film of Incoloy 800HT decreased as trace PbO addition into the high temperature water. - Highlights: • Trace PbO addition into the high temperature water block the formation of spinel oxides on Incoloy 800HT. • The donor density of oxide film decreases with trace PbO addition. • The current density of potentiodynamic polarization decreases of oxide film with trace PbO addition.

Injection moulding antireflective nanostructures

DEFF Research Database (Denmark)

Christiansen, Alexander Bruun; Clausen, Jeppe Sandvik; Mortensen, N. Asger

2014-01-01

We present a method for injection moulding antireflective nanostructures on large areas, for high volume production. Nanostructured black silicon masters were fabricated by mask-less reactive ion etching, and electroplated with nickel. The nickel shim was antistiction coated and used in an inject......We present a method for injection moulding antireflective nanostructures on large areas, for high volume production. Nanostructured black silicon masters were fabricated by mask-less reactive ion etching, and electroplated with nickel. The nickel shim was antistiction coated and used...

Injection moulding antireflective nanostructures

DEFF Research Database (Denmark)

Christiansen, Alexander Bruun; Clausen, Jeppe Sandvik; Mortensen, N. Asger

We present a method for injection moulding antireflective nanostructures on large areas, for high volume production. Nanostructured black silicon masters were fabricated by mask-less reactive ion etching, and electroplated with nickel. The nickel shim was antistiction coated and used in an inject......We present a method for injection moulding antireflective nanostructures on large areas, for high volume production. Nanostructured black silicon masters were fabricated by mask-less reactive ion etching, and electroplated with nickel. The nickel shim was antistiction coated and used...

Effect of LaB6 on the thermal shock property of MoSi2-SiC coating for carbon/carbon composites

International Nuclear Information System (INIS)

Li Ting; Li Hejun; Shi Xiaohong

2013-01-01

Highlights: ► LaB 6 -MoSi 2 -SiC and MoSi 2 -SiC multi-composition coatings were coated on C/C composites by pack cementation. ► The microstructure and thermal shock resistance of both coatings were investigated. ► The addition of LaB 6 can increase the compactness, flexural strength and fracture toughness of the MoSi 2 -SiC coating simultaneously. ► Both coatings bond well with the substrates before and after thermal cycling oxidation between 1773 K and room temperature. ► The LaB 6 -MoSi 2 -SiC coated C/C shows better thermal shock resistance than the MoSi 2 -SiC coated C/C. - Abstract: LaB 6 -MoSi 2 -SiC and MoSi 2 -SiC coatings were prepared on the surface of carbon/carbon composites by pack cementation method. The crystal structures of the coatings were measured by X-ray diffraction. The morphologies and element distributions were also analyzed by scanning electron microscopy and energy dispersive spectroscopy, respectively. The effect of LaB 6 on the microstructure and thermal shock resistance of MoSi 2 -SiC coating was investigated. The results indicated that the LaB 6 -MoSi 2 -SiC coating possessed a denser structure and superior thermal shock resistance. After 25 times of thermal cycling oxidation between 1773 K and room temperature, the weight losses of the LaB 6 -MoSi 2 -SiC and MoSi 2 -SiC coated samples were 0.627% and 2.019%, respectively.

Effect of Al-B2O3-TiO2 Exothermic System on Performances of Fly Ash Glass/Ceramic Composite Coating

Directory of Open Access Journals (Sweden)

Yajun An

2018-01-01

Full Text Available Glass/ceramic composite coatings were prepared on 40Cr steel matrix by thermo-chemical reaction with fly ash and a small amount of SiO2, Al2O3, MgO, and albite as main raw materials. On this basis, adding 10% Al-TiO2-B2O3 exothermic system, the morphology, phase, thermal shock resistance, and corrosion resistance of the coating were tested, and the influence of exothermic system on the structure and properties of the composite coating was studied. The experimental results show that the addition of exothermic system can promote the formation of NaB15, TiB2, Na2B4O7, Ca2Al2SiO7, and other new phases by thermo-chemical reaction; when compared to the composite coating without addition of exothermic system, combined with a good interface, higher compactness, and lower porosity. The highest micro hardness can be reached 725HV0.1. The number of thermal shock from 700 °C to room temperature can reach more than 50 times; acid, salt, oil immersion corrosion test, composite coating with exothermic system relative to the matrix increased by 27.40 times, 3.97 times, and 1.88 times, respectively. The overall performance is better than that of the composite coating without exothermic system.

Acoustoelectric Effect on the Responses of SAW Sensors Coated with Electrospun ZnO Nanostructured Thin Film

Directory of Open Access Journals (Sweden)

Zafer Ziya Ozturk

2012-08-01

Full Text Available In this study, zinc oxide (ZnO was a very good candidate for improving the sensitivity of gas sensor technology. The preparation of an electrospun ZnO nanostructured thin film on a 433 MHz Rayleigh wave based Surface Acoustic Wave (SAW sensor and the investigation of the acoustoelectric effect on the responses of the SAW sensor are reported. We prepared an electrospun ZnO nanostructured thin film on the SAW devices by using an electrospray technique. To investigate the dependency of the sensor response on the structure and the number of the ZnO nanoparticles, SAW sensors were prepared with different coating loads. The coating frequency shifts were adjusted to fall between 100 kHz and 2.4 MHz. The sensor measurements were performed against VOCs such as acetone, trichloroethylene, chloroform, ethanol, n-propanol and methanol vapor. The sensor responses of n-propanol have opposite characteristics to the other VOCs, and we attributed these characteristics to the elastic effect/acoustoelectric effect.

A study on erosive wear behavior of HVOF sprayed nanostructured WC-CoCr coatings

International Nuclear Information System (INIS)

Thakur, Lalit; Arora, Navneet

2013-01-01

WC-CoCr cermet coatings were deposited on stainless steel substrate using high-velocity oxy-fuel (HVOF) thermal spray process. The coatings were developed with two different thermal spray powders: one has WC grains of conventional micron size and the other is composed of nanosized (near-nanostructured) grains. HVOF spraying was assisted with in-flight particle temperature and velocity measurement system to control the process parameters that have resulted in quality coatings. Cavitation erosion testing was performed using a vibratory test apparatus based on ASTM standard G32-98. Surface morphology of powders and coatings was examined using the FESEM images, and phase identification was performed by XRD analysis. The erosion behavior of coatings and mechanism of material removal was discussed by examining the microstructure images of worn-out surfaces. WC-CoCr cermet coating deposited with nanosized WC grains exhibited higher cavitation erosion resistance as compared to conventional coating.

A study on erosive wear behavior of HVOF sprayed nanostructured WC-CoCr coatings

Energy Technology Data Exchange (ETDEWEB)

Thakur, Lalit; Arora, Navneet [Indian Institute of Technology Roorkee, Roorkee (India)

2013-05-15

WC-CoCr cermet coatings were deposited on stainless steel substrate using high-velocity oxy-fuel (HVOF) thermal spray process. The coatings were developed with two different thermal spray powders: one has WC grains of conventional micron size and the other is composed of nanosized (near-nanostructured) grains. HVOF spraying was assisted with in-flight particle temperature and velocity measurement system to control the process parameters that have resulted in quality coatings. Cavitation erosion testing was performed using a vibratory test apparatus based on ASTM standard G32-98. Surface morphology of powders and coatings was examined using the FESEM images, and phase identification was performed by XRD analysis. The erosion behavior of coatings and mechanism of material removal was discussed by examining the microstructure images of worn-out surfaces. WC-CoCr cermet coating deposited with nanosized WC grains exhibited higher cavitation erosion resistance as compared to conventional coating.

CrCuAgN PVD nanocomposite coatings: Effects of annealing on coating morphology and nanostructure

Energy Technology Data Exchange (ETDEWEB)

Liu, Xingguang, E-mail: xingguangliu1@gmail.com [Department of Materials Science and Engineering, Sir Robert Hadfield Building, The University of Sheffield, Mappin Street, Sheffield, S1 3JD (United Kingdom); Iamvasant, Chanon, E-mail: ciamvasant1@sheffield.ac.uk [Department of Materials Science and Engineering, Sir Robert Hadfield Building, The University of Sheffield, Mappin Street, Sheffield, S1 3JD (United Kingdom); Liu, Chang, E-mail: chang.liu@sheffield.ac.uk [Department of Materials Science and Engineering, Sir Robert Hadfield Building, The University of Sheffield, Mappin Street, Sheffield, S1 3JD (United Kingdom); Matthews, Allan, E-mail: allan.matthews@manchester.ac.uk [Pariser Building - B24 ICAM, School of Materials, The University of Manchester, Manchester, M13 9PL (United Kingdom); Leyland, Adrian, E-mail: a.leyland@sheffield.ac.uk [Department of Materials Science and Engineering, Sir Robert Hadfield Building, The University of Sheffield, Mappin Street, Sheffield, S1 3JD (United Kingdom)

2017-01-15

Highlights: • Coatings with nitrogen content up to 16 at.% exhibit a metallic Cr solid solution, even after post-coat annealing at 300 °C and 500 °C. • At higher N/Cr atomic ratios (approaching Cr{sub 2}N stoichiometry), chromium was still inclined to exist in solid solution with nitrogen, rather than as a ceramic nitride phase, even after annealing at 500 °C. • Transportation of Cu and Ag to the surface depends on annealing temperature, annealing duration, nitrogen concentration and ‘global’ Cu + Ag concentration. • Incorporation of copper appears to be a powerful strategy to enhance Ag mobility at low concentration (∼3 at.% Ag in this study) under moderately high service temperature. • A significant decrease in friction coefficient was obtained at room temperature after annealing, or during sliding wear testing at elevated temperature. - Abstract: CrCuAgN PVD nanocomposite coatings were produced using pulsed DC unbalanced magnetron sputtering. This investigation focuses on the effects of post-coat annealing on the surface morphology, phase composition and nanostructure of such coatings. In coatings with nitrogen contents up to 16 at.%, chromium exists as metallic Cr with N in supersaturated solid solution, even after 300 °C and 500 °C post-coat annealing. Annealing at 300 °C did not obviously change the phase composition of both nitrogen-free and nitrogen-containing coatings; however, 500 °C annealing resulted in significant transformation of the nitrogen-containing coatings. The formation of Ag aggregates relates to the (Cu + Ag)/Cr atomic ratio (threshold around 0.2), whereas the formation of Cu aggregates relates to the (Cu + Ag + N)/Cr atomic ratio (threshold around 0.5). The primary annealing-induced changes were reduced solubility of Cu, Ag and N in Cr, and the composition altering from a mixed ultra-fine nanocrystalline and partly amorphous phase constitution to a coarser, but still largely nanocrystalline structure. It was also

Cu-Au alloy nanostructures coated with aptamers: a simple, stable and highly effective platform for in vivo cancer theranostics

Science.gov (United States)

Ye, Xiaosheng; Shi, Hui; He, Xiaoxiao; Yu, Yanru; He, Dinggeng; Tang, Jinlu; Lei, Yanli; Wang, Kemin

2016-01-01

and lower cost was introduced to generate a novel Cu-Au alloy nanostructure produced by a simple, gentle and one-pot synthetic method. Having the good qualities of both Cu and Au, the irregularly-shaped Cu-Au alloy nanostructures showed several advantages over traditional Au nanorods, including a broad and intense near-infrared (NIR) absorption band from 400 to 1100 nm, an excellent heating performance under laser irradiation at different wavelengths and even a notable photostability against melting. Then, via a simple conjugation of fluorophore-labeled aptamers on the Cu-Au alloy nanostructures, active targeting and signal output were simultaneously introduced, thus constructing a theranostic platform based on fluorophore-labeled, aptamer-coated Cu-Au alloy nanostructures. By using human leukemia CCRF-CEM cancer and Cy5-labeled aptamer Sgc8c (Cy5-Sgc8c) as the model, a selective fluorescence imaging and NIR photothermal therapy was successfully realized for both in vitro cancer cells and in vivo tumor tissues. It was revealed that Cy5-Sgc8c-coated Cu-Au alloy nanostructures were not only capable of robust target recognition and stable signal output for molecular imaging in complex biological systems, but also killed target cancer cells in mice with only five minutes of 980 nm irradiation. The platform was found to be simple, stable, biocompatible and highly effective, and shows great potential as a versatile tool for cancer theranostics. Electronic supplementary information (ESI) available: Fig. S1, S2 and Table S1. See DOI: 10.1039/c5nr07017a

Frictional forces between hydrophilic and hydrophobic particle coated nanostructured surfaces

DEFF Research Database (Denmark)

Hansson, Petra M; Claesson, Per M.; Swerin, Agne

2013-01-01

Friction forces have long been associated with the famous Amontons' rule that states that the friction force is linearly dependent on the applied normal load, with the proportionality constant being known as the friction coefficient. Amontons' rule is however purely phenomenological and does...... not in itself provide any information on why the friction coefficient is different for different material combinations. In this study, friction forces between a colloidal probe and nanostructured particle coated surfaces in an aqueous environment exhibiting different roughness length scales were measured...... by utilizing the atomic force microscope (AFM). The chemistry of the surfaces and the probe was varied between hydrophilic silica and hydrophobized silica. For hydrophilic silica surfaces, the friction coefficient was significantly higher for the particle coated surfaces than on the flat reference surface. All...

Growth of ZnO nanostructures on Au-coated Si: Influence of growth temperature on growth mechanism and morphology

DEFF Research Database (Denmark)

Kumar, Rajendra; McGlynn, E.; Biswas, M.

2008-01-01

ZnO nanostructures were grown on Au-catalyzed Si silicon substrates using vapor phase transport at growth temperatures from 800 to 1150 degrees C. The sample location ensured a low Zn vapor supersaturation during growth. Nanostructures grown at 800 and 850 degrees C showed a faceted rodlike...... growth tended to dominate resulting in the formation of a porous, nanostructured morphology. In all cases growth was seen only on the Au-coated region. Our results show that the majority of the nanostructures grow via a vapor-solid mechanism at low growth temperatures with no evidence of Au nanoparticles...

Neutron irradiation and high temperature effects on amorphous Fe-based nano-coatings on steel - A macroscopic assessment

Science.gov (United States)

Simos, N.; Zhong, Z.; Dooryhee, E.; Ghose, S.; Gill, S.; Camino, F.; Şavklıyıldız, İ.; Akdoğan, E. K.

2017-06-01

The study revealed that loss of ductility in an amorphous Fe-alloy coating on a steel substrate composite structure was essentially prevented from occurring, following radiation with modest neutron doses of ∼2 × 1018 n/cm2. At the higher neutron dose of ∼2 × 1019, macroscopic stress-strain analysis showed that the amorphous Fe-alloy nanostructured coating, while still amorphous, experienced radiation-induced embrittlement, no longer offering protection against ductility loss in the coating-substrate composite structure. Neutron irradiation in a corrosive environment revealed exemplary oxidation/corrosion resistance of the amorphous Fe-alloy coating, which is attributed to the formation of the Fe2B phase in the coating. To establish the impact of elevated temperatures on the amorphous-to-crystalline transition in the amorphous Fe-alloy, electron microscopy was carried out which confirmed the radiation-induced suppression of crystallization in the amorphous Fe-alloy nanostructured coating.

Photoelectrochemical properties of hierarchical ZnO micro-nanostructure sensitized with Sb2S3 nanoparticles

Directory of Open Access Journals (Sweden)

Zhimin GUO

2016-02-01

Full Text Available By using electrochemical deposition method, and assisted with additions of PEG-400 and EDA, well-aligned ZnO nanorods and hierarchical ZnO micro-nanostructure are fabricated directly on indium doped tin oxide coated conducting glass (ITO substrate. The shell-core Sb2S3/ZnO nanorod structure and the shell-core hierarchical Sb2S3/ZnO micro-nanostructure are prepared by chemical bath deposition method. SEM, XRD, UV-Vis and photocurrent test are used to characterize the morphology, nanostructures and their photoelectrochemical properties. The studies show that the photocurrent on the array membranes with shell-core hierarchical Sb2S3/ZnO micro-nanostructure is apparently higher than that with shell-core Sb2S3/ZnO nanorods array.

Nanostructured composite reinforced material

Science.gov (United States)

Seals, Roland D [Oak Ridge, TN; Ripley, Edward B [Knoxville, TN; Ludtka, Gerard M [Oak Ridge, TN

2012-07-31

A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

Electrical and structural characterisation of nanostructured titania coatings deposited on interdigitated electrode system

International Nuclear Information System (INIS)

Milanovic, Marija; Stojanovic, Goran; Nikolic, Ljubica M.; Radovanovic, Milan; Skoric, Branko; Miletic, Aleksandar

2011-01-01

Highlights: → La/TiO 2 and Nb/TiO 2 nanocrystalline coatings as interdigitated electrode system for sensors. → A method for the computation of conductivity and relative permittivity was proposed. → Nb causes an increase of electrical properties, while La has the opposite effect. - Abstract: This paper presents the electrical properties of La- and Nb-doped nanostructured titanium dioxide (TiO 2 ) thin coatings deposited on the alumina substrate with gold electrodes in the interdigitated form to obtain appropriate devices for sensor application. Electrical parameters such as conductivity σ and permittivity ε were calculated using measured values of phase angle θ m , capacitance C m and resistance R m . These values were measured using an HP-4194A Impedance/Gain-Phase Analyzer with a Z-probe in the frequency range from 10 3 Hz to 10 8 Hz. The measured results showed that with addition of 2, 4 or 6 at% of lanthanum, conductivity and permittivity of analysed samples are decreasing, whereas the addition of niobium in the same percentage follows the opposite trend.

Multistep structural transition of hydrogen trititanate nanotubes into TiO{sub 2}-B nanotubes: a comparison study between nanostructured and bulk materials

Energy Technology Data Exchange (ETDEWEB)

Morgado, Edisson Jr [PETROBRAS S.A./CENPES, Research and Development Centre, Avenida Horacio Macedo, 950, Cidade Universitaria, Quadra 7, 21941-598 Rio de Janeiro-RJ (Brazil); Jardim, P M [Department of Materials Science and Metallurgy, Pontifical Catholic University, CP 38008, 22453-900 Rio de Janeiro-RJ (Brazil); Marinkovic, Bojan A [Department of Materials Science and Metallurgy, Pontifical Catholic University, CP 38008, 22453-900 Rio de Janeiro-RJ (Brazil); Rizzo, Fernando C [Department of Materials Science and Metallurgy, Pontifical Catholic University, CP 38008, 22453-900 Rio de Janeiro-RJ (Brazil); Abreu, Marco A S de [PETROBRAS S.A./CENPES, Research and Development Centre, Avenida Horacio Macedo, 950, Cidade Universitaria, Quadra 7, 21941-598 Rio de Janeiro-RJ (Brazil); Zotin, Jose L [PETROBRAS S.A./CENPES, Research and Development Centre, Avenida Horacio Macedo, 950, Cidade Universitaria, Quadra 7, 21941-598 Rio de Janeiro-RJ (Brazil); Araujo, Antonio S [Department of Chemistry, Federal University of Rio Grande do Norte, CP 1662, 59078-970 Natal-RN (Brazil)

2007-12-12

H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO{sub 2} followed by proton exchange were compared to their bulk H{sub 2}Ti{sub 3}O{sub 7} counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H{sub 2}Ti{sub 3}O{sub 7} nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H{sub 2}Ti{sub 3}O{sub 7} converts into TiO{sub 2}(B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 deg. C through topotactic mechanisms with the intermediate formation of nanostructured H{sub 2}Ti{sub 6}O{sub 13} and H{sub 2}Ti{sub 12}O{sub 25}, which are more condensed layered titanates eventually rearranging to TiO{sub 2}(B). Our results suggest that the intermediate tunnel structure H{sub 2}Ti{sub 12}O{sub 25} is the final layered intermediate phase, on which TiO{sub 2}(B) nucleates and grows. The conversion of nanostructured TiO{sub 2}(B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology.

Xanthine oxidase functionalized Ta2O5 nanostructures as a novel scaffold for highly sensitive SPR based fiber optic xanthine sensor.

Science.gov (United States)

Kant, Ravi; Tabassum, Rana; Gupta, Banshi D

2018-01-15

Fabrication and characterization of a surface plasmon resonance based fiber optic xanthine sensor using entrapment of xanthine oxidase (XO) enzyme in several nanostructures of tantalum (v) oxide (Ta 2 O 5 ) have been reported. Chemical route was adopted for synthesizing Ta 2 O 5 nanoparticles, nanorods, nanotubes and nanowires while Ta 2 O 5 nanofibers were prepared by electrospinning technique. The synthesized Ta 2 O 5 nanostructures were characterized by photoluminescence, scanning electron microscopy, UV-Visible spectra and X-ray diffraction pattern. The probes were fabricated by coating an unclad core of the fiber with silver layer followed by the deposition of XO entrapped Ta 2 O 5 nanostructures. The crux of sensing mechanism relies on the modification of dielectric function of sensing layer upon exposure to xanthine solution of diverse concentrations, reflected in terms of shift in resonance wavelength. The sensing probe coated with XO entrapped Ta 2 O 5 nanofibers has been turned out to possess maximum sensitivity amongst the synthesized nanostructures. The probe was optimized in terms of pH of the sample and the concentration of XO entrapped in Ta 2 O 5 nanofibers. The optimized sensing probe possesses a remarkably good sensitivity of 26.2nm/µM in addition to linear range from 0 to 3µM with an invincible LOD value of 0.0127µM together with a response time of 1min. Furthermore, probe selectivity with real sample analysis ensure the usage of the sensor for practical scenario. The results reported open a novel perspective towards a sensitive, rapid, reliable and selective detection of xanthine. Copyright © 2017 Elsevier B.V. All rights reserved.

Osseointegration is improved by coating titanium implants with a nanostructured thin film with titanium carbide and titanium oxides clustered around graphitic carbon

Energy Technology Data Exchange (ETDEWEB)

Veronesi, Francesca [Laboratory of Preclinical and Surgical Studies, Rizzoli Orthopedic Institute, Via Di Barbiano 1/10, Bologna 40136 (Italy); Giavaresi, Gianluca; Fini, Milena [Laboratory of Preclinical and Surgical Studies, Rizzoli Orthopedic Institute, Via Di Barbiano 1/10, Bologna 40136 (Italy); Laboratory of Biocompatibility, Innovative Technologies and Advanced Therapies, Department Rizzoli RIT, Via Di Barbiano 1/10, Bologna 40136 (Italy); Longo, Giovanni [CNR Istituto di Struttura della Materia, CNR, Via del Fosso del Cavaliere 100, 00133 Roma (Italy); Ioannidu, Caterina Alexandra; Scotto d' Abusco, Anna [Dept. of Biochemical Sciences, Sapienza University of Roma, Ple A. Moro 5, 00185 Roma (Italy); Superti, Fabiana; Panzini, Gianluca [Dept. of Technologies and Health, Istituto Superiore di Sanità, Viale Regina Elena, 299 Roma (Italy); Misiano, Carlo [Romana Film Sottili, Anzio, Roma (Italy); Palattella, Alberto [Dept. of Clinical Sciences and Translational Medicine, Tor Vergata University, Via Montpellier 1, 00133 Roma (Italy); Selleri, Paolo; Di Girolamo, Nicola [Exotic Animals Clinic, Via S. Giovannini 53, 00137 Roma (Italy); Garbarino, Viola [Dept. of Radiology, S.M. Goretti Hospital, Via G. Reni 2, 04100 Latina (Italy); Politi, Laura [Dept. of Biochemical Sciences, Sapienza University of Roma, Ple A. Moro 5, 00185 Roma (Italy); Scandurra, Roberto, E-mail: roberto.scandurra@uniroma1.it [Dept. of Biochemical Sciences, Sapienza University of Roma, Ple A. Moro 5, 00185 Roma (Italy)

2017-01-01

Titanium implants coated with a 500 nm nanostructured layer, deposited by the Ion Plating Plasma Assisted (IPPA) technology, composed of 60% graphitic carbon, 25% titanium oxides and 15% titanium carbide were implanted into rabbit femurs whilst into the controlateral femurs uncoated titanium implants were inserted as control. At four time points the animals were injected with calcein green, xylenol orange, oxytetracycline and alizarin. After 2, 4 and 8 weeks femurs were removed and processed for histology and static and dynamic histomorphometry for undecalcified bone processing into methylmethacrylate, sectioned, thinned, polished and stained with Toluidine blue and Fast green. The overall bone-implant contacts rate (percentage of bone-implant contacts/weeks) of the TiC coated implant was 1.6 fold than that of the uncoated titanium implant. The histomorphometric analyses confirmed the histological evaluations. More precisely, higher Mineral Apposition Rate (MAR, μm/day) (p < 0.005) and Bone Formation Rate (BFR, μm{sup 2}/μm/day) (p < 0.0005) as well as Bone Implant Contact (Bic) and Bone Ingrowth values (p < 0.0005) were observed for the TiC coated implants compared to uncoated implants. In conclusion the hard nanostructured TiC layer protects the bulk titanium implant against the harsh conditions of biological tissues and in the same time, stimulating adhesion, proliferation and activity of osteoblasts, induces a better bone-implant contacts of the implant compared to the uncoated titanium implant. - Highlights: • Ti implants were coated with a nanostructured film composed of C{sub gr}, TiC and TiO{sub x}. • The TiC layer stimulates adhesion, proliferation and activity of osteoblasts. • Uncoated and TiC coated titanium implants were implanted in rabbit femurs. • Bone-implant contacts of TiC coated implants were higher than that of uncoated. • Mineral Apposition Rate of TiC coated implants were higher than that of uncoated.

European coatings conference - Marine coatings. Proceedings

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-07-01

This volume contains 13 lectures (manuscripts or powerpoint foils) with the following topics: 1. Impact of containerization on polyurethane and polyurea in marine and protective coatings (Malte Homann); 2. The application of combinatorial/high-throughput methods to the development of marine coatings (Bret Chisholm); 3. Progress and perspectives in the AMBIO (advanced nanostructured surfaces for the control of biofouling) Project (James Callow); 4. Release behaviour due to shear and pull-off of silicone coatings with a thickness gradient (James G. Kohl); 5. New liquid rheology additives for high build marine coatings (Andreas Freytag); 6. Effective corrosion protection with polyaniline, polpyrrole and polythiophene as anticorrosice additives for marine paints (Carlos Aleman); 7. Potential applications of sol gel technology for marine applications (Robert Akid); 8: Performance of biocide-free Antifouling Coatings for leisure boats (Bernd Daehne); 9. Novel biocidefree nanostructured antifouling coatings - can nano do the job? (Corne Rentrop); 10. One component high solids, VOC compliant high durability finish technology (Adrian Andrews); 11. High solid coatings - the hybrid solution (Luca Prezzi); 12. Unique organofunctional silicone resins for environmentally friendly high-performance coatings (Dieter Heldmann); 13. Silicone-alkyd paints for marine applications: from battleship-grey to green (Thomas Easton).

Comparing nanostructured hydroxyapatite coating on AZ91 alloy samples via sol-gel and electrophoretic deposition for biomedical applications.

Science.gov (United States)

Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan

2014-12-01

Magnesium is one of the most critical elements in hard tissues regeneration and therefore causes speeding up the restoration of harmed bones, while high deterioration rate of magnesium in body fluid restricts it to be used as biodegradable implants. Alloying magnesium with some relatively nobler metals such as aluminium, zinc, rare earth elements, magnesium-bioceramics composites, and surface modification techniques are some of the routes to control magnesium corrosion rate. In this study AZ91 magnesium alloy had been coated by nanostructured hydroxyapatite via sol-gel dip coating and electrophoretical methods to survey the final barricade properties of the obtained coatings. In order to perform electrophoretic coating, powders were prepared by sol-gel method, and then the powders deposited on substrates utilizing direct current electricity. Zeta potentials of the electrophoresis suspensions were measured to determine a best mode for good quality coatings. Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM) were used to confirm nanoscale dimension, and the uniformity of the nanostructured hydroxyapatite coating, respectively. Fourier Transform-Infrared and X-ray diffraction analysis were utilized for functional group and phase structure evaluation of the prepared coatings, correspondingly. Electrochemical corrosion tests were performed in SBF at 37±1 (°)C which revealed considerable increase in corrosion protection resistivity and corrosion current density for electrophoretic coated specimens versus sol-gel coated specimens. Results showed that both sol-gel and electrophoretical techniques seem to be suitable to coat magnesium alloys for biomedical applications but electrophoretic coating technique is a better choice due to the more homogeneity and more crystalline structure of the coating.

Carbon-coated boron using low-cost naphthalene for substantial enhancement of Jc in MgB2 superconductor

Energy Technology Data Exchange (ETDEWEB)

Ranot, Mahipal; Shinde, K. P.; Oh, Y. S.; Kang, S. H.; Jang, S. H.; Hwang, D. Y.; Chung, K. C. [Korea Institute of Materials Science, Changwon (Korea, Republic of)

2017-09-15

Carbon coating approach is used to prepare carbon-doped MgB{sub 2} bulk samples using low-cost naphthalene (C{sub 10}H{sub 8}) as a carbon source. The coating of carbon (C) on boron (B) powders was achieved by direct pyrolysis of naphthalene at 120 degrees C and then the C-coated B powders were mixed well with appropriate amount of Mg by solid state reaction method. X-ray diffraction analysis revealed that there is a noticeable shift in (100) and (110) Bragg reflections towards higher angles, while no shift was observed in (002) reflections for MgB2 doped with carbon. As compared to un-doped MgB{sub 2}, a systematic enhancement in Jc(H) properties with increasing carbon doping level was observed for naphthalene-derived C-doped MgB{sub 2} samples. The substantial enhancement in Jc is most likely due to the incorporation of C into MgB{sub 2} lattice and the reduction in crystallite size, as evidenced by the increase in the FWHM values for doped samples.

Neutron irradiation and high temperature effects on amorphous Fe-based nano-coatings on steel – A macroscopic assessment

International Nuclear Information System (INIS)

Simos, N.; Zhong, Z.; Dooryhee, E.; Ghose, S.; Gill, S.

2017-01-01

Here, this study revealed that loss of ductility in an amorphous Fe-alloy coating on a steel substrate composite structure was essentially prevented from occurring, following radiation with modest neutron doses of ~2 x 10 18 n/cm 2 . At the higher neutron dose of ~2 x 10 19 , macroscopic stress-strain analysis showed that the amorphous Fe-alloy nanostructured coating, while still amorphous, experienced radiation-induced embrittlement, no longer offering protection against ductility loss in the coating-substrate composite structure. Neutron irradiation in a corrosive environment revealed exemplary oxidation/corrosion resistance of the amorphous Fe-alloy coating, which is attributed to the formation of the Fe 2 B phase in the coating. To establish the impact of elevated temperatures on the amorphous-to-crystalline transition in the amorphous Fe-alloy, electron microscopy was carried out which confirmed the radiation-induced suppression of crystallization in the amorphous Fe-alloy nanostructured coating.

Understanding the wetting properties of nanostructured selenium coatings: the role of nanostructured surface roughness and air-pocket formation

Directory of Open Access Journals (Sweden)

Tran PA

2013-05-01

Full Text Available Phong A Tran,1,2 Thomas J Webster31Department of Chemical and Biomolecular Engineering, University of Melbourne, Melbourne, VIC, Australia; 2The Particulate Fluid Processing Centre, University of Melbourne, Melbourne, VIC, Australia; 3Department of Chemical Engineering and Program in Bioengineering, Northeastern University, Boston, MA, USAAbstract: Wetting properties of biomaterials, in particular nanomaterials, play an important role, as these influence interactions with biological elements, such as proteins, bacteria, and cells. In this study, the wetting phenomenon of titanium substrates coated with selenium nanoparticles was studied using experimental and mathematical modeling tools. Importantly, these selenium-coated titanium substrates were previously reported to increase select protein adsorption (such as vitronectin and fibronectin, to decrease bacteria growth, and increase bone cell growth. Increased selenium nanoparticle coating density resulted in higher contact angles but remained within the hydrophilic regime. This trend was found in disagreement with the Wenzel model, which is widely used to understand the wetting properties of rough surfaces. The trend also did not fit well with the Cassie–Baxter model, which was developed to understand the wetting properties of composite surfaces. A modified wetting model was thus proposed in this study, to understand the contributing factors of material properties to the hydrophilicity/hydrophobicity of these nanostructured selenium-coated surfaces. The analysis and model created in this study can be useful in designing and/or understanding the wetting behavior of numerous biomedical materials and in turn, biological events (such as protein adsorption as well as bacteria and mammalian cell functions.Keywords: hydrophilicity, hydrophobicity, Wenzel model, Cassie–Baxter model, free energy, implant material, proteins, cells, bacteria

Electrophoretic deposition of nanostructured hydroxyapatite coating on AZ91 magnesium alloy implants with different surface treatments

Energy Technology Data Exchange (ETDEWEB)

Rojaee, Ramin, E-mail: raminrojaee@aim.com [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Raeissi, Keyvan [Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of)

2013-11-15

Bio-absorbable magnesium (Mg) based alloys have been introduced as innovative orthopedic implants during recent years. It has been specified that rapid degradation of Mg based alloys in physiological environment should be restrained in order to be utilized in orthopedic trauma fixation and vascular intervention. In this developing field of healthcare materials, micro-arc oxidation (MAO), and MgF{sub 2} conversion coating were exploited as surface pre-treatment of AZ91 magnesium alloy to generate a nanostructured hydroxyapatite (n-HAp) coating via electrophoretic deposition (EPD) method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) techniques were used to characterize the obtained powder and coatings. The potentiodynamic polarization tests were carried out to evaluate the corrosion behavior of the coated and uncoated specimens, and in vitro bioactivity evaluation were performed in simulated body fluid. Results revealed that the MAO/n-HAp coated AZ91 Mg alloy samples with a rough topography and lower corrosion current density leads to a lower Mg degradation rate accompanied by high bioactivity.

Electrophoretic deposition of nanostructured hydroxyapatite coating on AZ91 magnesium alloy implants with different surface treatments

International Nuclear Information System (INIS)

Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan

2013-01-01

Bio-absorbable magnesium (Mg) based alloys have been introduced as innovative orthopedic implants during recent years. It has been specified that rapid degradation of Mg based alloys in physiological environment should be restrained in order to be utilized in orthopedic trauma fixation and vascular intervention. In this developing field of healthcare materials, micro-arc oxidation (MAO), and MgF 2 conversion coating were exploited as surface pre-treatment of AZ91 magnesium alloy to generate a nanostructured hydroxyapatite (n-HAp) coating via electrophoretic deposition (EPD) method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) techniques were used to characterize the obtained powder and coatings. The potentiodynamic polarization tests were carried out to evaluate the corrosion behavior of the coated and uncoated specimens, and in vitro bioactivity evaluation were performed in simulated body fluid. Results revealed that the MAO/n-HAp coated AZ91 Mg alloy samples with a rough topography and lower corrosion current density leads to a lower Mg degradation rate accompanied by high bioactivity.

Electrophoretic deposition of nanostructured hydroxyapatite coating on AZ91 magnesium alloy implants with different surface treatments

Science.gov (United States)

Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan

2013-11-01

Bio-absorbable magnesium (Mg) based alloys have been introduced as innovative orthopedic implants during recent years. It has been specified that rapid degradation of Mg based alloys in physiological environment should be restrained in order to be utilized in orthopedic trauma fixation and vascular intervention. In this developing field of healthcare materials, micro-arc oxidation (MAO), and MgF2 conversion coating were exploited as surface pre-treatment of AZ91 magnesium alloy to generate a nanostructured hydroxyapatite (n-HAp) coating via electrophoretic deposition (EPD) method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) techniques were used to characterize the obtained powder and coatings. The potentiodynamic polarization tests were carried out to evaluate the corrosion behavior of the coated and uncoated specimens, and in vitro bioactivity evaluation were performed in simulated body fluid. Results revealed that the MAO/n-HAp coated AZ91 Mg alloy samples with a rough topography and lower corrosion current density leads to a lower Mg degradation rate accompanied by high bioactivity.

Photocatalytic performance of Sn-doped and undoped TiO2 nanostructured thin films under UV and vis-lights

International Nuclear Information System (INIS)

Arpac, E.; Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, Nadir; Sayilkan, H.

2007-01-01

Sn-doped and undoped nano-TiO 2 particles have been synthesized by hydrotermal process without solvent at 200 deg. C in 1 h. Nanostructure-TiO 2 based thin films have been prepared on glass substrate by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, SEM, BET and UV-vis-NIR techniques. The photocatalytic performance of the films were tested for degradation of Malachite Green dye in solution under UV and vis-lights. The results showed that (a) hydrothermally synthesized nano-TiO 2 particles are fully anatase crystalline form and are easily dispersed in water, (b) the coated surfaces have nearly super-hydrophilic properties and (c) the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO 2 thin film

Optically enhanced SnO{sub 2}/CdSe core/shell nanostructures grown by sol-gel spin coating method

Energy Technology Data Exchange (ETDEWEB)

Kumar, Vijay, E-mail: vijaynadda83@gmail.com; Goswami, Y. C. [School of Physical Sciences, ITM University, Turari, Gwalior, MP 474001 (India); Rajaram, P. [School of Studies in Physics, Jiwaji University, Gwalior MP 474011 (India)

2015-08-28

Synthesis of SnO{sub 2}/CdSe metal oxide/ chalcogenide nanostructures on glass micro slides using ultrasonic sol-gel process followed by spin coating has been reported. Stannous chloride, cadmium chloride and selenium dioxide compounds were used for Sn, Cd and Se precursors respectively. Ethylene glycol was used as complexing agent. The samples were characterized by XRD, SEM, AFM and UV-spectrophotometer. All the peaks shown in diffractograms are identified for SnO{sub 2}. Peak broadening observed in core shell due to stress behavior of CdSe lattice. Scanning electron microscope and AFM exhibits the conversion of cluster in to nanorods structures forms. Atomic force microscope shows the structures in nanorods form and a roughness reduced 1.5194 nm by the deposition of CdSe. Uv Visible spectra shows a new absorption edge in the visible region make them useful for optoelectronic applications.

In vivo study of nanostructured diopside (CaMgSi{sub 2}O{sub 6}) coating on magnesium alloy as biodegradable orthopedic implants

Energy Technology Data Exchange (ETDEWEB)

Razavi, Mehdi, E-mail: mrzavi2659@gmail.com [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Savabi, Omid [Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Razavi, Seyed Mohammad [School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Heidari, Fariba; Manshaei, Maziar [Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan 81746-73461 (Iran, Islamic Republic of); Vashaee, Daryoosh [School of Electrical and Computer Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); Tayebi, Lobat, E-mail: lobat.tayebi@okstate.edu [School of Materials Science and Engineering, Helmerich Advanced Technology Research Center, Oklahoma State University, Tulsa, OK 74106 (United States); School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078 (United States)

2014-09-15

Highlights: • In vitro biocompatibility of biodegradable Mg alloy was improved by diopside coating. • In vivo biocompatibility of biodegradable Mg alloy was improved by diopside coating. • Degradation behavior of biodegradable Mg alloy was improved by diopside coating. - Abstract: In order to improve the corrosion resistance and bioactivity of a biodegradable magnesium alloy, we have recently prepared a nanostructured diopside (CaMgSi{sub 2}O{sub 6}) coating on AZ91 magnesium alloy through a combined micro-arc oxidation (MAO) and electrophoretic deposition (EPD) method (reported elsewhere). In this work, we performed a detailed biocompatibility analysis of the implants made by this material and compared their performance with those of the uncoated and micro arc oxidized magnesium implants. The biocompatibility evaluation of samples was performed by culturing L-929 cells and in vivo animal study, including implantation of samples in greater trochanter of rabbits, radiography and histological examinations. The results from both the in vitro and in vivo studies indicated that the diopside/MAO coated magnesium implant significantly enhanced cell viability, biodegradation resistance and new bone formation compared with both the uncoated and the micro-arc oxidized magnesium implants. Our data provides an example of how the proper surface treatment of magnesium implants can overcome their drawbacks in terms of high degradation rate and gas bubble formation under physiological conditions.

Microstructure evolution of Fe-based nanostructured bainite coating by laser cladding

International Nuclear Information System (INIS)

Guo, Yanbing; Li, Zhuguo; Yao, Chengwu; Zhang, Ke; Lu, Fenggui; Feng, Kai; Huang, Jian; Wang, Min; Wu, Yixiong

2014-01-01

Highlights: • The laser cladding and isothermal holding are used to fabricate nanobainite coating. • Fine prior austenite is obtained to accelerate the bainite transformation. • Low transformation temperature results in fine bainite ferrite and film austenite. • Retained austenite volume fraction in bainite coating is determined by XRD. • Evolution of carbon content in austenite and ferrite is analyzed. - Abstract: A Fe-based coating with nano-scale bainitic microstructure was fabricated using laser cladding and subsequent isothermal heat treatment. The microstructure of the coating was observed and analyzed using optical microscope (OM), field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The results showed that nanostructured bainitic ferrite and carbon-enriched retained austenite distributed uniformly in the coating. Blocky retained austenite was confined to the prior austenite grain boundaries resulting from the elements segregation. The bainitic microstructure obtained at 250 °C had a finer scale compared with that obtained at 300 °C. The volume fraction of austenite increased with increasing transformation temperature for the fully transformed bainitic coating. The bainitic transformation was accelerated as a result of the fine prior austenite generated during the laser cladding. The evolution of the carbon contents in bainitic ferrite and retained austenite revealed the diffusionless mechanism of the bainitic transformation

Composite Cu/Fe/MgB{sub 2} superconducting wires and MgB{sub 2}/YSZ/Hastelloy coated conductors for ac and dc applications

Energy Technology Data Exchange (ETDEWEB)

Glowacki, B A [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge (United Kingdom); Majoros, M [Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge (United Kingdom); Vickers, M [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge (United Kingdom); Eisterer, M [Atomic Institute of the Austrian Universities, A-1020 Vienna (Austria); Toenies, S [Atomic Institute of the Austrian Universities, A-1020 Vienna (Austria); Weber, H W [Atomic Institute of the Austrian Universities, A-1020 Vienna (Austria); Fukutomi, M [National Institute for Materials Science, Superconducting Materials Center, 1-2-1, Sengen, Ibaraki (Japan); Komori, K [National Institute for Materials Science, Superconducting Materials Center, 1-2-1, Sengen, Ibaraki (Japan); Togano, K [National Institute for Materials Science, Superconducting Materials Center, 1-2-1, Sengen, Ibaraki (Japan)

2003-02-01

We discuss the results of a study of MgB{sub 2} multifilamentary conductors and coated conductors from the point of view of their future dc and ac applications. The correlation between the slope of the irreversibility line induced by neutron irradiation defects and in situ structural imperfections and the critical temperature and critical current density is discussed with respect to the conductor performance and applicability. We debate the possible origin of the observed anomalous decrease of ac susceptibility at 50 K in copper clad in situ powder-in-tube MgB{sub 2} wires. Different conductor preparation methods and conductor architectures, and attainable critical current densities are presented. Some numerical results on critical currents, thermal stability and ac losses of future MgB{sub 2} multifilamentary and coated conductors with magnetic cladding of their filaments are also discussed.

Impact of structure and morphology of nanostructured ceria coating on AISI 304 oxidation kinetics

International Nuclear Information System (INIS)

Aadhavan, R.; Suresh Babu, K.

2017-01-01

Highlights: • Ceria coating reduced the oxidation kinetics of AISI304 by 3–4 orders. • Lower deposition rate (0.1 Å/s) resulted in dense and uniform coating. • Substrate temperature of 100 °C provided coating with smaller crystallite size. • Surface morphology of the coating has strong influence in oxidation protection. - Abstract: Nanostructured ceria-based coatings are shown to be protective against high-temperature oxidation of AISI 304 due to the dynamics of oxidation state and associated defects. However, the processing parameters of deposition have a strong influence in determining the structural and morphological aspects of ceria. The present work focuses on the effect of variation in substrate temperature (50–300 °C) and deposition rate (0.1–50 Å/s) of ceria in electron beam physical vapour evaporation method and correlates the changes in structure and morphology to high-temperature oxidation protection. Unlike deposition rate, substrate temperature exhibited a profound influence on crystallite size (7–18 nm) and oxygen vacancy concentration. Upon isothermal oxidation at 1243 K for 24 h, bare AISI 304 exhibited a linear mass gain with a rate constant of 3.0 ± 0.03 × 10"−"3 kg"2 m"−"4 s"−"1 while ceria coating lowered the kinetics by 3–4 orders. Though the thickness of the coating was kept constant at 2 μm, higher deposition rate offered one order lower protection due to the porous nature of the coating. Variation in the substrate temperature modulated the porosity as well as oxygen vacancy concentration and displayed the best protection for coatings deposited at moderate substrate temperature. The present work demonstrates the significance of selecting appropriate processing parameters to obtain the required morphology for efficient high-temperature oxidation protection.

Impact of structure and morphology of nanostructured ceria coating on AISI 304 oxidation kinetics

Energy Technology Data Exchange (ETDEWEB)

Aadhavan, R.; Suresh Babu, K., E-mail: sureshbabu.nst@pondiuni.edu.in

2017-07-31

Highlights: • Ceria coating reduced the oxidation kinetics of AISI304 by 3–4 orders. • Lower deposition rate (0.1 Å/s) resulted in dense and uniform coating. • Substrate temperature of 100 °C provided coating with smaller crystallite size. • Surface morphology of the coating has strong influence in oxidation protection. - Abstract: Nanostructured ceria-based coatings are shown to be protective against high-temperature oxidation of AISI 304 due to the dynamics of oxidation state and associated defects. However, the processing parameters of deposition have a strong influence in determining the structural and morphological aspects of ceria. The present work focuses on the effect of variation in substrate temperature (50–300 °C) and deposition rate (0.1–50 Å/s) of ceria in electron beam physical vapour evaporation method and correlates the changes in structure and morphology to high-temperature oxidation protection. Unlike deposition rate, substrate temperature exhibited a profound influence on crystallite size (7–18 nm) and oxygen vacancy concentration. Upon isothermal oxidation at 1243 K for 24 h, bare AISI 304 exhibited a linear mass gain with a rate constant of 3.0 ± 0.03 × 10{sup −3} kg{sup 2} m{sup −4} s{sup −1} while ceria coating lowered the kinetics by 3–4 orders. Though the thickness of the coating was kept constant at 2 μm, higher deposition rate offered one order lower protection due to the porous nature of the coating. Variation in the substrate temperature modulated the porosity as well as oxygen vacancy concentration and displayed the best protection for coatings deposited at moderate substrate temperature. The present work demonstrates the significance of selecting appropriate processing parameters to obtain the required morphology for efficient high-temperature oxidation protection.

Effects of air dielectric barrier discharge plasma treatment time on surface properties of PBO fiber

International Nuclear Information System (INIS)

Wang Qian; Chen Ping; Jia Caixia; Chen, Mingxin; Li Bin

2011-01-01

In this paper, the effects of air dielectric barrier discharge (DBD) plasma treatment time on surface properties of poly(p-phenylene benzobisoxazole) (PBO) fiber were investigated. The surface characteristics of PBO fiber before and after the plasma treatments were analyzed by dynamic contact angle (DCA) analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). DCA measurements indicated that the surface wettability of PBO fiber was improved significantly by increasing the fiber surface free energy via air DBD plasma treatments. The results were confirmed by the improvement of adhesion of a kind of thermoplastic resin to PBO fiber which was observed by SEM, showing that more resin was adhering evenly to the fiber surface. AFM measurement revealed that the surface topography of PBO fiber became more complicated and the surface roughness was greatly enhanced after the plasma treatments, and XPS analysis showed that some new polar groups (e.g. -O-C=O) were introduced on plasma treated PBO fiber surface. The results of this study also showed that the surface properties of PBO fiber changed with the elongation of plasma treatment time.

Electrocatalytic reduction of H2O2 by Pt nanoparticles covalently bonded to thiolated carbon nanostructures

International Nuclear Information System (INIS)

You, Jung-Min; Kim, Daekun; Jeon, Seungwon

2012-01-01

Highlights: ► Novel thiolated carbon nanostructures – platinum nanoparticles [t-GO-C(O)-pt and t-MWCNT-C(O)-S-pt] have been synthesized, and [t-GO-C(O)-pt and t-MWCNT-C(O)-S-pt] denotes as t-GO-pt and t-MWCNT-Pt in manuscript, respectively. ► The modified electrode denoted as PDDA/t-GO-pt/GCE was used for the electrochemical determination of H 2 O 2 for the first time. ► The results show that PDDA/t-GO-pt nanoparticles have the promising potential as the basic unit of the electrochemical biosensors for the detection of H 2 O 2 . ► The proposed H 2 O 2 biosensors exhibited wide linear ranges and low detection limits, giving fast responses within 10 s. - Abstract: Glassy carbon electrodes were coated with thiolated carbon nanostructures – multi-walled carbon nanotubes and graphene oxide. The subsequent covalent addition of platinum nanoparticles and coating with poly(diallydimethylammonium chloride) resulted in biosensors that detected hydrogen peroxide through its electrocatalytic reduction. The sensors were easily and quickly prepared and showed improved sensitivity to the electrocatalytic reduction of H 2 O 2 . The Pt nanoparticles covalently bonded to the thiolated carbon nanostructures were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. Cyclic voltammetry and amperometry were used to characterize the biosensors’ performances. The sensors exhibited wide linear ranges and low detection limits, giving fast responses within 10 s, thus demonstrating their potential for use in H 2 O 2 analysis.

Electrochemical impedance spectroscopy and corrosion behaviour of Al{sub 2}O{sub 3}-Ni nano composite coatings

Energy Technology Data Exchange (ETDEWEB)

Ciubotariu, Alina-Crina [Dunarea de Jos, University of Galati, Metallurgy and Materials Science Faculty, Competences Center Interfaces-Tribocorrosion-Electrochemical Systems, CC-ITES, 47 Domneasca Street, 80008 Galati (Romania)], E-mail: Alina.Ciubotariu@ugal.ro; Benea, Lidia [Dunarea de Jos, University of Galati, Metallurgy and Materials Science Faculty, Competences Center Interfaces-Tribocorrosion-Electrochemical Systems, CC-ITES, 47 Domneasca Street, 80008 Galati (Romania); Lakatos-Varsanyi, Magda [Bay Zoltan Foundation, Institute for Materials Science and Technology, Budapest H-1116 (Hungary); Dragan, Viorel [Dunarea de Jos, University of Galati, Metallurgy and Materials Science Faculty, Competences Center Interfaces-Tribocorrosion-Electrochemical Systems, CC-ITES, 47 Domneasca Street, 80008 Galati (Romania)

2008-05-20

In this paper, the results on the electrochemical impedance spectroscopy and corrosion properties of electrodeposited nanostructured Al{sub 2}O{sub 3}-Ni composite coatings are presented. The nanocomposite coatings were obtained by codeposition of alumina nanoparticles (13 nm) with nickel during plating process. The coating thickness was 50 {mu}m on steel support and an average of nano Al{sub 2}O{sub 3} particles inside of coatings at 15 vol.% was present. The structure of the coatings was investigated by scanning electron microscopy (SEM). It has been found that the codeposition of Al{sub 2}O{sub 3} particles with nickel disturbs the nickel coating's regular surface structure. The electrochemical behavior of the coatings in the corrosive solutions was investigated by polarization potentiodynamic and electrochemical impedance spectroscopy methods. As electrochemical test solutions 0.5 M sodium chloride and 0.5 M potassium sulphate were used in a three electrode open cell. The corrosion potential is shifted to more negative values for nanostructured coatings in 0.5 M sodium chloride. The polarization resistance in 0.5 M sodium chloride decreases in 24 h, but after that increases slowly. In 0.5 M potassium sulphate solution the polarization resistance decreases after 2 h and after 30 h of immersion the polarization resistance is higher than that of the beginning value. The corrosion rate calculated by polarization potentiodynamic curves obtained after 30 min from immersion in solution is smaller for nanostructured coatings in 0.5 M potassium sulphate (4.74 {mu}m/year) and a little bit bigger in 0.5 M sodium chloride (5.03 {mu}m/year)

Enhanced bioactivity and biocompatibility of nanostructured hydroxyapatite coating by hydrothermal annealing

International Nuclear Information System (INIS)

Hahn, Byung-Dong; Lee, Jeong-Min; Park, Dong-Soo; Choi, Jong-Jin; Ryu, Jungho; Yoon, Woon-Ha; Choi, Joon-Hwan; Lee, Byoung-Kuk; Kim, Jong-Woo; Kim, Hyoun-Ee; Kim, Seong-Gon

2011-01-01

The crystallinity of hydroxyapatite (HA) coatings prepared by aerosol deposition may be increased by heating in air or low-temperature hydrothermal processing. From the X-ray diffraction and Fourier transform infrared spectroscopy results, it was revealed that the crystallinity of the HA coatings significantly increased after the post-annealing. Transmission electron microscopy showed that the conventional furnace heating induced the substantial growth of the HA crystallites, whereas the hydrothermal treatment did not bring about any remarkable change in the HA crystallite size, which remained below 20 nm. The bioactivity of the HA coatings was estimated by the acellular simulated body fluid immersion test. After immersion for 7 days, newly-precipitated apatite crystals were only observed on the surfaces of the samples hydrothermally treated at 170 and 190 deg. C. In addition, the alkaline phosphatase activity of MC3T3-E1 preosteoblast cells cultured on the hydrothermally treated samples was significantly higher than those on the as-deposited coating and conventional furnace heated samples. The enhanced bioactivity and excellent biological in vitro cellular response of the hydrothermally treated samples were attributed to their nanostructured nature and high degree of crystallinity.

Nanostructured sol-gel coatings doped with cerium nitrate as pre-treatments for AA2024-T3

International Nuclear Information System (INIS)

Zheludkevich, M.L.; Serra, R.; Montemor, M.F.; Yasakau, K.A.; Salvado, I.M. Miranda; Ferreira, M.G.S.

2005-01-01

Nanostructured hybrid sol-gel coatings doped with cerium ions were investigated in the present work as pre-treatments for the AA2024-T3 alloy. The sol-gel films have been synthesized from tetraethylorthosilicate (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) precursors. Additionally the hybrid sol was doped with zirconia nanoparticles prepared from hydrolyzed tetra-n-propoxyzirconium (TPOZ). Cerium nitrate, as corrosion inhibitor, was added into the hybrid matrix or into the oxide nanoparticles. The chemical composition and the structure of the hybrid sol-gel films were studied by XPS (X-ray photoelectron spectroscopy) and AFM (atomic force microscopy), respectively. The evolution of the corrosion protection properties of the sol-gel films was studied by EIS (electrochemical impedance spectroscopy), which can provide quantitative information on the role of the different pre-treatments. Different equivalent circuits, for different stages of the corrosion processes, were used in order to model the coating degradation. The models were supported by SEM (scanning electron microscopy) measurements. The results show that the sol-gel films containing zirconia nanoparticles present improved barrier properties. Doping the hybrid nanostructured sol-gel coatings with cerium nitrate leads to additional improvement of the corrosion protection. The zirconia particles present in the sol-gel matrix seem to act as nanoreservoirs providing a prolonged release of cerium ions. The nanostructured sol-gel films doped with cerium nitrate can be proposed as a potential candidate for substitution of the chromate pre-treatments for AA2024-T3

Impact of structure and morphology of nanostructured ceria coating on AISI 304 oxidation kinetics

Science.gov (United States)

Aadhavan, R.; Suresh Babu, K.

2017-07-01

Nanostructured ceria-based coatings are shown to be protective against high-temperature oxidation of AISI 304 due to the dynamics of oxidation state and associated defects. However, the processing parameters of deposition have a strong influence in determining the structural and morphological aspects of ceria. The present work focuses on the effect of variation in substrate temperature (50-300 °C) and deposition rate (0.1-50 Å/s) of ceria in electron beam physical vapour evaporation method and correlates the changes in structure and morphology to high-temperature oxidation protection. Unlike deposition rate, substrate temperature exhibited a profound influence on crystallite size (7-18 nm) and oxygen vacancy concentration. Upon isothermal oxidation at 1243 K for 24 h, bare AISI 304 exhibited a linear mass gain with a rate constant of 3.0 ± 0.03 × 10-3 kg2 m-4 s-1 while ceria coating lowered the kinetics by 3-4 orders. Though the thickness of the coating was kept constant at 2 μm, higher deposition rate offered one order lower protection due to the porous nature of the coating. Variation in the substrate temperature modulated the porosity as well as oxygen vacancy concentration and displayed the best protection for coatings deposited at moderate substrate temperature. The present work demonstrates the significance of selecting appropriate processing parameters to obtain the required morphology for efficient high-temperature oxidation protection.

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

Science.gov (United States)

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

Synthesis and characterization of in situ TiC–TiB2 composite coatings by reactive plasma spraying on a magnesium alloy

International Nuclear Information System (INIS)

Zou Binglin; Tao Shunyan; Huang Wenzhi; Khan, Zuhair S.; Fan Xizhi; Gu Lijian; Wang Ying; Xu Jiaying; Cai Xiaolong; Ma Hongmei; Cao Xueqiang

2013-01-01

Highlights: ► TiC–TiB 2 composites coatings were produced on Mg alloy by reactive plasma spraying. ► Phase composition, microstructure and wear resistance of the coatings were studied. ► The resultant product in the coatings was composed of TiC and TiB 2 . ► The produced coatings displayed porous and dense microstructures. ► The synthesized coatings exhibited good wear resistance for Mg alloy substrate. - Abstract: TiC–TiB 2 composite coatings were successfully synthesized using the technique of reactive plasma spraying (RPS) on a magnesium alloy. Phase composition, microstructure and wear resistance of the coatings were characterized by using X-ray diffraction, scanning electron microscopy and pin-on-disk wear test, respectively. The results showed that the resultant product in the RPS coatings was composed of TiC and TiB 2 . Depending on the ignition of self-propagating high-temperature synthesis reaction in the agglomerate particles, the RPS coatings displayed porous and dense microstructures. The porosity of the RPS coatings, to some extent, decreased when the feed powders were plasma sprayed with Ni powders. The RPS coatings provided good wear resistance for the substrate under various loads. For high loads (e.g., ≥15 N), the wear resistance could be significantly improved by the proper addition of Ni into the RPS coatings.

Humidity-sensitive characteristics of PbCrO4-PbO thick film elements. PbCrO4-PbO kei atsumaku soshi no kanshitsu tokusei

Energy Technology Data Exchange (ETDEWEB)

Kaneko, F [Shonan Institute of Technology, Kanagawa (Japan); Nanba, N [Kantogakuin University, Tokyo (Japan)

1992-12-20

This paper describes humidity-sensitive characteristics, which depend on the host composition being PbCrO4 or Pb2CrO5, in the system PbCrO4 combined with various oxides, such as Al2O3, Fe2O3, ZrO2, SnO2, TiO2, ThO2, and Ta2O5. In order to confirm the predominant phase over elements in the system PbCrO4-PbO, the effect of composition and microstructure on the humidity-sensitive characteristics of thick film elements were examined. Consequently, it was found that the humidity-sensitivity in low humidity region increased as the host composition of elements changed from hydrophobic PbCrO4 to hydrophilic Pb2CrO5. It was also shown that these results can be interpreted by a humidity-sensitive mechanism proposed for hydrophilic Pb2CrO5. Furthermore, an absorption model of H2O molecules on to the surface of Pb2CrO5 in the PbCrO4-PbO system humidity sensor was provided. 4 refs., 12 figs.

Revealing the nanostructure of calcium phosphate coatings using HRTEM/FIB techniques

International Nuclear Information System (INIS)

Solla, E.L.; Rodríguez-González, B.; Aguiar, H.; Rodríguez-Valencia, C.; Serra, J.; González, P.

2016-01-01

Herein, we report on the micro- and nanostructure of the calcium phosphate coating produced by pulsed laser deposition (PLD), using focused ion beam (FIB) lamella sample preparation and transmission electron microscopy (TEM) as the characterization technique. The initial selected area electron diffraction (SAED) data demonstrated the presence of hydroxyapatite (HA) over any other possible calcium phosphate crystalline structure and the polycrystalline nature of the coating. Moreover, the SAED analyses showed clear textured ring patterns coherent with the presence of a preferred orientation in the HA nano-crystal growth. The SAED data also indicated that the coating appears to be textured in the 〈002〉 crystalline direction. Dark-field images obtained using 002 as the working reflection showed a clear oriented crystal growth in columns, from bottom to top. These columns have a peculiar arrangement of nano-crystals since, in some cases, the preferred orientation appears to start at a certain distance from the substrate. Direct d-spacing measurements on high-resolution TEM images provided further proof of the presence of an HA nano-crystal structure. The reported data may be of interest in the future to adjust the microstructure of the HA coatings. - Highlights: •The FIB lift-out technique allows a very site-specific sample preparation method for HRTEM analysis. •It also permits a fast assessment of the HA coating thickness and elemental composition (EDS). •The coatings exhibit a nano-crystalline nature, with a texturing effect along the 002 planes. •PLD is suitable for the production of crystalline c-axis oriented hydroxyapatite coatings. •The crystalline HA phase in the PLD coating is very similar to the present in bone.

Revealing the nanostructure of calcium phosphate coatings using HRTEM/FIB techniques

Energy Technology Data Exchange (ETDEWEB)

Solla, E.L., E-mail: esolla@uvigo.es [Servicio de Microscopía Electrónica, CACTI, University of Vigo, Campus As Lagoas-Marcosende, 36310 Vigo (Spain); Rodríguez-González, B. [Servicio de Microscopía Electrónica, CACTI, University of Vigo, Campus As Lagoas-Marcosende, 36310 Vigo (Spain); Aguiar, H.; Rodríguez-Valencia, C.; Serra, J.; González, P. [Applied Physics Department, School of Industrial Engineering, University of Vigo, Campus As Lagoas-Marcosende, 36310 Vigo (Spain)

2016-12-15

Herein, we report on the micro- and nanostructure of the calcium phosphate coating produced by pulsed laser deposition (PLD), using focused ion beam (FIB) lamella sample preparation and transmission electron microscopy (TEM) as the characterization technique. The initial selected area electron diffraction (SAED) data demonstrated the presence of hydroxyapatite (HA) over any other possible calcium phosphate crystalline structure and the polycrystalline nature of the coating. Moreover, the SAED analyses showed clear textured ring patterns coherent with the presence of a preferred orientation in the HA nano-crystal growth. The SAED data also indicated that the coating appears to be textured in the 〈002〉 crystalline direction. Dark-field images obtained using 002 as the working reflection showed a clear oriented crystal growth in columns, from bottom to top. These columns have a peculiar arrangement of nano-crystals since, in some cases, the preferred orientation appears to start at a certain distance from the substrate. Direct d-spacing measurements on high-resolution TEM images provided further proof of the presence of an HA nano-crystal structure. The reported data may be of interest in the future to adjust the microstructure of the HA coatings. - Highlights: •The FIB lift-out technique allows a very site-specific sample preparation method for HRTEM analysis. •It also permits a fast assessment of the HA coating thickness and elemental composition (EDS). •The coatings exhibit a nano-crystalline nature, with a texturing effect along the 002 planes. •PLD is suitable for the production of crystalline c-axis oriented hydroxyapatite coatings. •The crystalline HA phase in the PLD coating is very similar to the present in bone.

Preparation and characterization of amorphous SiO2 coatings deposited by mirco-arc oxidation on sintered NdFeB permanent magnets

International Nuclear Information System (INIS)

Xu, J.L.; Xiao, Q.F.; Mei, D.D.; Zhong, Z.C.; Tong, Y.X.; Zheng, Y.F.; Li, L.

2017-01-01

Amorphous SiO 2 coatings were prepared on sintered NdFeB magnets by micro-arc oxidation (MAO) in silicate solution. The surface and cross-sectional morphologies, element and phase composition, corrosion resistance and magnetic properties of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization test and physical properties measurements system (PPMS). The results showed that the surface morphologies of the coatings exhibited the “coral reef” like structure, different from the typical MAO porous structure. With increasing the voltages, the thickness of the coatings increased from 12.72 to 19.90 µm, the content of Si element increased, while the contents of Fe, Nd and P elements decreased. The coatings were mainly composed of amorphous SiO 2 and a few amorphous Fe 2 O 3 and Nd 2 O 3 . The amorphous SiO 2 coatings presented excellent thermal shock resistance, while the thermal shock resistance decreased with increasing the voltages. The corrosion resistance of the coatings increased with increasing the voltages, and it could be enhanced by one order of magnitude compared to the uncoated NdFeB magnets. The MAO coatings slightly decreased the magnetic properties of the NdFeB samples in different degrees. - Highlights: • Amorphous SiO 2 coatings were prepared on sintered NdFeB magnets by micro-arc oxidation. • The coatings presented excellent thermal shock resistance. • The corrosion resistance could be enhanced by one order of magnitude. • The MAO coatings slightly decreased the magnetic properties of the NdFeB samples.

Effect of PbO on the elastic behavior of ZnO–P2O5 glass systems

Directory of Open Access Journals (Sweden)

H.A.A. Sidek

Full Text Available A series of ternary phosphate glasses in the form of 40(P2O5–(60 − xZnO–xPbO and 50(P2O5–(50 − xZnO–xPbO where x = 0–60 mol%, have been successfully prepared by conventional melt quenching technique. Both longitudinal and shear ultrasonic velocities were measured in different compositions of PbO using the MBS8000 ultrasonic data acquisition system at 10 MHz frequency and at room temperature. The ultrasonic velocity data, the density and the calculated elastic moduli are found to be composition dependent and discussed in terms of PbO modifiers. The correlation of elastic moduli with the atomic packing density of these glasses was discussed. To predict the compositional dependence of elastic moduli of this glass system, the interpretation of the variation in the experimental elastic behavior observed has been studied based on various of the bond compression and the Makishima–Mackenzie models. Keywords: Elastic moduli, Glasses, Zinc phosphate, Bond compression, Makishima–Mackenzie models

Fouling release nanostructured coatings based on PDMS-polyurea segmented copolymers

KAUST Repository

Fang, Jason

2010-05-01

The bulk and surface characteristics of a series of coatings based on PDMS-polyurea segmented copolymers were correlated to their fouling release performance. Incorporation of polyurea segments to PDMS backbone gives rise to phase separation with the extensively hydrogen bonded hard domains creating an interconnected network that imparts mechanical rigidity. Increasing the compositional complexity of the system by including fluorinated or POSS-functionalized chain extenders or through nanoclay intercalation, confers further thermomechanical improvements. In analogy to the bulk morphology, the surface topography also reflects the compositional complexity of the materials, displaying a wide range of motifs. Investigations on settlement and subsequent removal of Ulva sporelings on those nanostructured surfaces indicate that the work required to remove the microorganisms is significantly lower compared to coatings based on standard PDMS homopolymer. All in all, the series of materials considered in this study demonstrate advanced fouling release properties, while exhibiting superior mechanical properties and, thus, long term durability. © 2010 Elsevier Ltd.

Effects of PbO-B2O3 Glass Doping on the Sintering Temperature and Piezoelectric Properties of 0.35Pb (Ni1/3Nb2/3)O3-0.65Pb(Zr0.41Ti0.59)O3 Ceramics

Science.gov (United States)

Yi, Jinqiao; Shen, Meng; Liu, Sisi; Jiang, Shenglin

2015-12-01

0.35Pb(Ni1/3Nb2/3)O3-0.65Pb(Zr0.41Ti0.59)O3 (PNN-PZT) ceramics doped with 0.5PbO-0.5B2O3 glass have been synthesized by the conventional solid-state sintering technique. The effects of 0.5PbO-0.5B2O3 glass on the sintering temperature and piezoelectric properties of PNN-PZT ceramics were studied. The results indicated that the sintering temperature of PNN-PZT was significantly reduced due to the incorporation of 0.5PbO-0.5B2O3 glass dopant. When the content of 0.5PbO-0.5B2O3 glass was 0.5 wt.%, the sintering temperature of PNN-PZT was observed to reduce from above 1200°C to 920°C while the samples maintained high density (7.91 g/cm3), excellent piezoelectric constant ( d 33 = 479 pC/N), large electromechanical coupling coefficient ( K p = 0.55), and relatively low electromechanical quality factor ( Q m = 79). Moreover, large dielectric constant ( ɛ 33 T / ɛ 0 = 2904) and low dielectric loss (tan δ = 0.0166) were obtained in this work.

Optical and structural properties of nanostructured CeO2:Tb3+ film

International Nuclear Information System (INIS)

Ansari, Anees A.; Singh, S.P.; Malhotra, B.D.

2011-01-01

Nanostructured CeO 2 :Tb 3+ film has been fabricated on glass substrate through sol-gel technique via dip-coating process. (NH 4 ) 2 Ce(NO 3 ) 6 , Tb(NO 3 ) 3 .6H 2 O, ethylene glycol have been used as precursors for sol preparation. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV/VIS and photoluminescence (PL) spectral studies have been employed to analyze the structural and optical properties of the film. XRD pattern has been used to analyze the crystallite nature and calculated particle size by Scherrer equation of nanostructured CeO 2 :Tb 3+ film, found in the range 3-4 nm. SEM image has been observed to analyze the surface topography of the film which is well porous, highly agglomerated and uniformly distributed nanoparticles on the film surface. Optical band gap of nanostructured CeO 2 :Tb 3+ film has been estimated as 3.57 eV. A significant enhancement in band shape of CeO 2 :Tb 3+ spectrum has been observed in PL spectra, showed their promising usages as optical materials in optoelectronic devices.

Nanostructured layer-by-layer films containing phaeophytin-b: Electrochemical characterization for sensing purposes

International Nuclear Information System (INIS)

Nunes Pauli, Gisele Elias; Araruna, Felipe B.; Eiras, Carla; Leite, José Roberto S.A.; Chaves, Otemberg Souza; Filho, Severino Gonçalves Brito; Vanderlei de Souza, Maria de Fátima; Chavero, Lucas Natálio; Sartorelli, Maria Luisa

2015-01-01

This paper reports the study and characterization of a new platform for practical applications, where the use of phaeophytin-b (phaeo-b), a compound derived from chlorophyll, was characterized and investigated for sensing purposes. Modified electrodes with nanostructured phaeo-b films were fabricated via the layer-by-layer (LbL) technique, where phaeo-b was assembled with cashew gum, a polysaccharide, or with poly(allylamine) hydrochloride (PAH). The multilayer formation was investigated with UV–Vis spectroscopy by monitoring the absorption band associated to phaeo-b at approximately 410 nm, where distinct molecular interactions between the materials were verified. The morphology of the films was analyzed by atomic force microscopy (AFM). The electrochemical properties through redox behavior of phaeo-b were studied with cyclic voltammetry. The produced films were applied as sensors for hydrogen peroxide (H 2 O 2 ) detection. In terms of sensing, the cashew/phaeo-b film exhibited the most promising result, with a fast response and broad linear range upon the addition of H 2 O 2 . This approach provides a simple and inexpensive method for development of a nonenzymatic electrochemical sensor for H 2 O 2 . - Highlights: • Potential applications of phaeophytin-b • Low-cost method to produce sensitive nanostructured films • Electrochemical sensor based on phaeophytin-b and cashew gum

Electrodeposited Ni-B coatings: Formation and evaluation of hardness and wear resistance

International Nuclear Information System (INIS)

Krishnaveni, K.; Sankara Narayanan, T.S.N.; Seshadri, S.K.

2006-01-01

The formation of electrodeposited Ni-B alloy coatings using a dimethylamine borane (DMAB) modified Watt's nickel bath and evaluation of their structural characteristics, hardness and wear resistance are discussed. The boron content in the electrodeposited Ni-B alloy coating is determined by the ratio of rate of reduction of nickel and rate of decomposition of DMAB. The boron content of the electrodeposited Ni-B coating decreases as the current density increased from 0.4 to 4 A dm -2 . XRD diffraction pattern of electrodeposited Ni-B coatings in their as-plated condition exhibits the presence of Ni (1 1 1) (2 0 0) and (2 2 0) reflections with (1 1 1) texture. Heat treatment at 400 deg. C for 1 h has resulted in the formation of nickel boride phases, which results in an increase in hardness and wear resistance. The mechanism of wear in electrodeposited Ni-B coatings is intensive plastic deformation of the coating due to the ploughing action of the hard counter disk

Tantalum coating on TiO2 nanotubes induces superior rate of matrix mineralization and osteofunctionality in human osteoblasts

International Nuclear Information System (INIS)

Frandsen, Christine J.; Brammer, Karla S.; Noh, Kunbae; Johnston, Gary; Jin, Sungho

2014-01-01

Nanostructured surface geometries have been the focus of a multitude of recent biomaterial research, and exciting findings have been published. However, only a few publications have directly compared nanostructures of various surface chemistries. The work herein directly compares the response of human osteoblast cells to surfaces of identical nanotube geometries with two well-known orthopedic biomaterials: titanium oxide (TiO 2 ) and tantalum (Ta). The results reveal that the Ta surface chemistry on the nanotube architecture enhances alkaline phosphatase activity, and promotes a ∼ 30% faster rate of matrix mineralization and bone-nodule formation when compared to results on bare TiO 2 nanotubes. This study implies that unique combinations of surface chemistry and nanostructure may influence cell behavior due to distinctive physico-chemical properties. These findings are of paramount importance to the orthopedics field for understanding cell behavior in response to subtle alterations in nanostructure and surface chemistry, and will enable further insight into the complex manipulation of biomaterial surfaces. With increased focus in the field of orthopedic materials research on nanostructured surfaces, this study emphasizes the need for careful and systematic review of variations in surface chemistry in concurrence with nanotopographical changes. - Highlights: • A TiO 2 nanotube surface structure was coated with tantalum. • Osteoblast cell response was compared between the tantalum coated and as-formed TiO 2 nanotube surface. • We observed superior rates of bone matrix mineralization and osteoblast maturation on the tantalum coated nanotube surface

PBO Borehole Strainmeters and Pore Pressure Sensors: Recording Hydrological Strain Signals

Science.gov (United States)

Gottlieb, M. H.; Hodgkinson, K. M.; Mencin, D.; Henderson, D. B.; Johnson, W.; Van Boskirk, E.; Pyatt, C.; Mattioli, G. S.

2017-12-01

UNAVCO operates a network of 75 borehole strainmeters along the west coast of the United States and Vancouver Island, Canada as part of the Plate Boundary Observatory (PBO), the geodetic component of the NSF-funded Earthscope program. Borehole strainmeters are designed to detect variations in the strain field at the nanostrain level and can easily detect transient strains caused by aseismic creep events, Episodic Tremor and Slip (ETS) events and seismically induced co- and post-seimic signals. In 2016, one strainmeter was installed in an Oklahoma oil field to characterize in-situ deformation during CO2 injection. Twenty-three strainmeter sites also have pore pressure sensors to measure fluctuations in groundwater pressure. Both the strainmeter network and the pore pressure sensors provide unique data against which those using water-level measurements, GPS time-series or InSAR data can compare possible subsidence signals caused by groundwater withdrawal or fluid re-injection. Operating for 12 years, the PBO strainmeter and pore pressure network provides a long-term, continuous, 1-sps record of deformation. PBO deploys GTSM21 tensor strainmeters from GTSM Technologies, which consist of four horizontal strain gauges stacked vertically, at different orientations, within a single 2 m-long instrument. The strainmeters are typically installed at depths of 200 to 250 m and grouted into the bottom of 15 cm diameter boreholes. The pore pressure sensors are Digiquartz Depth Sensors from Paros Scientific. These sensors are installed in 2" PVC, sampling groundwater through a screened section 15 m above the co-located strainmeter. These sensors are also recording at 1-sps with a resolution in the hundredths of hPa. High-rate local barometric pressure data and low-rate rainfall data also available at all locations. PBO Strainmeter and pore pressure data are available in SEED, SAC-ASCII and time-stamped ASCII format from the IRIS Data Managements Center. Strainmeter data are

Structure, spectra and thermal, mechanical, Faraday rotation properties of novel diamagnetic SeO2-PbO-Bi2O3-B2O3 glasses

Science.gov (United States)

Chen, Qiuling; Su, Kai; Li, Yantao; Zhao, Zhiwei

2018-06-01

Faraday rotation diamagnetic glass has attracted research attentions in photonics, sensing and magneto optical devices due to their high refractive index, wide transmittance in UV and Fourier transform infrared (FT-IR) range and temperature independent Faraday rotation. Selenite modified heavy metal oxides glasses with composition of xSeO2-(10-x) B2O3-45PbO-45Bi2O3 (x = 0, 1, 5 and 10mol%) and 15%SeO2-40%PbO-45%Bi2O3 have been fabricated by melt-quenching method in present study. The influence of SeO2 on glass forming ability, thermal, mechanical properties and Faraday rotation were evaluated through X-ray Diffraction (XRD), Fourier transforms infrared spectra (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), Vicker's hardness and Verdet constant measurements. XRD spectra reveal that the good vitrification was achieved for glass with SeO2 amounts ≤10% even without B2O3. FT-IR, Raman and XPS spectra ascertain the existence of characteristic vibration of SeO4, SeO3, PbO4, BiO3 and BO3 units. The incorporation of SeO2 increases the connectivity of glassy network by increasing the Tg, thermal stability and mechanical hardness. The small band gap, high polarizable Se4+ ions and isolated SeO3 units contribute to Faraday rotation improvement.

Sputter deposition of wear-resistant coatings within the system Zr-B-N

Energy Technology Data Exchange (ETDEWEB)

Mitterer, C; Uebleis, A; Ebner, R [Inst. fuer Metallkunde und Werkstoffpruefung, Montanuniv., Leoben (Austria)

1991-07-07

Wear-resistant coatings of zirconium boride and zirconium boron nitride were deposited on steel and molybdenum substrates employing non-reactive as well as reactive d.c. magnetron sputtering using zirconium diboride targets. The characterization of the coatings was done by means of scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The results are discussed in connection with measured mechanical coating properties such as microhardness and adhesion. The optical properties of the coatings were determined using a CIE-L{sup *}a{sup *}b{sup *} colorimeter and specialized corrosion and abrasion tests. Non-reactive sputtering using ZrB{sub 2} targets results in the formation of coatings with a columnar structure and predominantly (001)-orientated ZrB{sub 2} crystals. Coatings deposited at low nitrogen flow rates exhibit very fine-grained or even fracture amorphous structures with a hexagonal Zr-B-N phase derived from the ZrB{sub 2} lattice. A further increase of the nitrogen flow leads to an amorphous film growth. The maximum Vickers microhardness of the coatings was found to be approximately 2300 HV 0.02. Zr-B and Zr-B-N coatings offer a wide range of interesting colours as well as good corrosion and wear resistance. (orig.).

Dual-Layer Oxidation-Protective Plasma-Sprayed SiC-ZrB2/Al2O3-Carbon Nanotube Coating on Graphite

Science.gov (United States)

Ariharan, S.; Sengupta, Pradyut; Nisar, Ambreen; Agnihotri, Ankur; Balaji, N.; Aruna, S. T.; Balani, Kantesh

2017-02-01

Graphite is used in high-temperature gas-cooled reactors because of its outstanding irradiation performance and corrosion resistance. To restrict its high-temperature (>873 K) oxidation, atmospheric-plasma-sprayed SiC-ZrB2-Al2O3-carbon nanotube (CNT) dual-layer coating was deposited on graphite substrate in this work. The effect of each layer was isolated by processing each component of the coating via spark plasma sintering followed by isothermal kinetic studies. Based on isothermal analysis and the presence of high residual thermal stress in the oxide scale, degradation appeared to be more severe in composites reinforced with CNTs. To avoid the complexity of analysis of composites, the high-temperature activation energy for oxidation was calculated for the single-phase materials only, yielding values of 11.8, 20.5, 43.5, and 4.5 kJ/mol for graphite, SiC, ZrB2, and CNT, respectively, with increased thermal stability for ZrB2 and SiC. These results were then used to evaluate the oxidation rate for the composites analytically. This study has broad implications for wider use of dual-layer (SiC-ZrB2/Al2O3) coatings for protecting graphite crucibles even at temperatures above 1073 K.

Surface preparation of gold nanostructures on glass by ultraviolet ozone and oxygen plasma for thermal atomic layer deposition of Al{sub 2}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Lancaster, Cady A., E-mail: lancaster@chem.utah.edu; Shumaker-Parry, Jennifer S., E-mail: shumaker-parry@chem.utah.edu

2016-08-01

Thin film deposition to create robust plasmonic nanomaterials is a growing area of research. Plasmonic nanomaterials have tunable optical properties and can be used as substrates for surface-enhanced spectroscopies. Due to the surface sensitivity and the dependence of the near-field behavior on structural details, degradation from cleaning or spectroscopic interrogation causes plasmonic nanostructures to lose distinctive localized surface plasmon resonances or exhibit diminished optical near-field enhancements over time. To decrease degradation, conformal thin films of alumina are deposited on nanostructured substrates using atomic layer deposition. While film growth on homogenous surfaces has been studied extensively, atomic layer deposition-based film growth on heterogeneous nanostructured surfaces is not well characterized. In this report, we have evaluated the impact of oxygen plasma and ultraviolet ozone pre-treatments on Au nanoparticle substrates for thin film growth by monitoring changes in plasmonic response and nanostructure morphology. We have found that ultraviolet ozone is more effective than oxygen plasma for cleaning gold nanostructured surfaces, which is in contrast to bulk films of the same material. Our results show that oxygen plasma treatment negatively impacts the nanostructure and alumina coating based on both scanning electron microscopy analysis of morphology and changes in the plasmonic response. - Highlights: • Plasmonic response indicates oxygen plasma damages Au structures and Al{sub 2}O{sub 3} films. • Ultraviolet ozone (UVO) re-activates aged Al{sub 2}O{sub 3}-coated Au nanostructures. • UVO treatments do not damage Au or Al{sub 2}O{sub 3}-coated nanostructures.

Application of nano-structured coatings to mitigate flow-accelerated corrosion in secondary pipe systems of nuclear power plants

International Nuclear Information System (INIS)

Kim, Seung Hyun; Kim, Jong Jin; Yoo, Seung Chang; Kim, Ji Hyun

2014-01-01

Carbon steel is widely used as a structural material in secondary pipe systems. However, the passivity of carbon steel is not sufficient for protection in secondary water chemistry with a very fast-flowing fluid because of the dissolution of ferrous and magnetite ions and surface friction at the interface of the coolant and pipe surface. There have been many efforts to mitigate flow-accelerated corrosion through adoption of advanced water chemistries such as optimized dissolve oxygen (DO) concentration and temperature, as well as usage of new additives such as monoethanol amine (ETA) to adjust pH. However, these mitigation techniques pose certain challenges relating to the compatibility of new water chemistries with the steam generator, the thermal efficiency of the secondary side, etc. In this study, to improve the passivity of carbon steel, nanostructured coatings especially nanoparticle-enhanced surface coatings were adopted to improve resistance to corrosion and wear. Nanoparticles in the coating matrix help decrease the electrochemical potential compared coatings without nanoparticles, and thus help improve the mechanical properties, especially hardness, through precipitation. In other words, nanoparticle-enhanced surface coatings have the potential to mitigate flow-accelerated corrosion in secondary pipe systems. As candidate coatings, TiO 2 - and SiC-enhanced electrolytic and electroless nickel plating and Fe-Cr-W amorphous metallic coatings (AMC) were selected by acquiring the Pourbaix diagram with thermodynamic calculations. Both TiO 2 and SiC show a stable state in secondary water chemistry, and it is estimated that Fe-Cr-W can be applied to secondary water chemistry because it has a similar chemical composition to carbon steel. Electron microscopic analysis results with scanning electron microscopy (SEM) and tunneling electron microscopy (TEM) show the distribution of TiO 2 nanoparticles in the nickel matrix coating layer, whereas the SiC nanoparticles

PBO Operations in Alaska and Cascadia, Combining Regions and Collaborating with our Regional Partners

Science.gov (United States)

Austin, K. E.; Boyce, E. S.; Dausz, K.; Feaux, K.; Mattioli, G. S.; Pyatt, C.; Willoughby, H.; Woolace, A. C.

2015-12-01

During the last year, the Alaska and the Cascadia regions of the EarthScope Plate Boundary Observatory (PBO) network were combined into a single management unit. While both remain distinct regions with their own challenges and engineering staff, every effort has been made to operate as a single team to improve efficiency and provide the highest possible data quality and uptime. Over the last several years a concerted effort has been made to work collaboratively with other institutions and stakeholders to defray ongoing costs by sharing staff and resources. UNAVCO currently operates four integrated GPS/seismic stations in collaboration with the Alaska Earthquake Center, eight with the Alaska Volcano Observatory, and three with the EarthScope TA. By the end of 2015, PBO and TA plan to install another 3 integrated and/or co-located geodetic and seismic systems. While most of these are designed around existing PBO stations, the 2014 installation at Middleton Island is a new station for both groups, providing PBO with an opportunity to expand geodetic data in Alaska. There were two major joint maintenance efforts in 2015:, the largest was a 5 day mission among PBO, AVO, and TA, which shared boat, helicopter, and staff on and around Augustine Volcano; the second, was a 10 day helicopter mission shared between AVO and PBO on Unimak Island. PBO Pacific Northwest is working closely with University of Washington to co-locate at least 9 Earthquake Early Warning Systems, which include the addition of strong motion sensors and high speed RT telemetry at PBO sites. The project is managed by University of Washington but UNAVCO is providing land contact information and infrastructure support. Summer 2015 upgrades include a complete overhaul of aging radio technology at two major networks and several small radio networks in Cascadia. The upgrades will increase reliability and enhance the speed of existing telemetry infrastructure and will continue through summer 2018.

Formation and investigation of multilayer nanostructured coatings TiN/MoN for different layers thicknesses with c-pvd

International Nuclear Information System (INIS)

Pogrebnyak, A.D.; Bondar, O.V.; Postol'nyj, B.A.; Andreev, A.A.; Abadias, G.; Beresnev, V.M.; Sobol', O.B.

2013-01-01

Multilayer coatings based on TiN/MoN were obtained using the vacuum arc evaporation cathode method (C-PVD). Multilayers thickness was in the range 6,7 ÷ 8,7 μm and monolayers thickness was 2, 10, 20 and 40 nm. Vacuum-arc unit Bulat 6 was used for depositions. For the analysis of multilayer structures and properties of nanostructured coatings XRD analysis method was used (D8 ADVANCE, Bruker). For elemental composition and morphology investigation of the surface layers and multilayered coatings SEM (JEOL-7001F) with EDX attachment was used. Also HRTEM method was used to analyze the phase composition. In addition, this article provides investigation of hardness by Micro-Hardness Tester CSM (Switzerland). AFM was used for additional analysis of the topography and surface roughness of these coatings. This investigation have revealed the relationship between the layers thicknesses, substrate potential, the annealing process, physical and mechanical properties of samples. (authors)

Magnetization jumps in nanostructured Nd–Fe–B alloy at low temperatures

International Nuclear Information System (INIS)

Neznakhin, D.S.; Bolyachkin, A.S.; Volegov, A.S.; Markin, P.E.; Andreev, S.V.; Kudrevatykh, N.V.

2015-01-01

Magnetic properties of the nanostructured isotropic alloy on the base of Nd 2 Fe 14 B type phase were investigated at low temperatures. The evaluated average grain size of this phase was much smaller than its critical single domain diameter. Hence the magnetization and demagnetization processes were expected to be performed by coherent magnetization rotation. For such coercivity type system magnetization jumps were revealed on the demagnetization hysteresis loop branch in the vicinity of the coercive force at temperatures below 4 K. It was shown that magnetization jumps have a stochastic behavior and their number strongly depends on the temperature and the mass of measured samples. High temperature spikes corresponding to magnetization discontinuities were observed. All these results allowed to propose that magnetization jumps in nanostructured magnetics with magnetization rotation reversal processes comply with the local heating model. - Highlights: • Magnetization reversals of the nanostructured Nd–Fe–B-type alloy were obtained below 4 K. • Magnetization jumps were first observed for magnetization rotation coercivity type magnets. • Staircase magnetization reversal was explained within the framework of the local heating model

Thermodiffusion Mo-B-Si coating on VN-3 niobium alloy

International Nuclear Information System (INIS)

Kozlov, A.T.; Lazarev, Eh.M.; Monakhova, L.A.; Shestova, V.F.; Romanovich, I.V.

1985-01-01

Protective properties of complex Mo-B-Si-coating on niobium alloy VN-3 (4.7 mass.% Mo, 1.1 mass.% Zr, 0.1 mass.% C) have been studied. It is established, that the complex Mo-B-Si-coating ensures protection from oxidation of niobium alloys in the temperature range of 800-1200 degC for 1000-1500 hr, at 1600 degC - for 10 hr. High heat resistance of Mo-B-Si - coating at 800-1200 degC is determined by the presence of amorphous film of SiOΛ2 over the layer MoSiΛ2 and barrier boride layer on the boundary with the metal protected; decrease in the coating heat resistance at 1600 degC is related to the destruction of boride layer, decomposition of MoSiΛ2 for lower cilicides and loosening of SiOΛ2 film

Microstructural and electrochemical characterization of Ni/Ti/sub 2/N composite coating for sintered NdFeB permanent magnets

International Nuclear Information System (INIS)

Ali, A.; Ahmad, A.; Deen, K.M.; Ahmad, R.

2009-01-01

Sintered NdFeB magnets have complex microstructure that makes them susceptible to corrosion in humid or moist environments. The paper presents the anticorrosion characteristics of a novel Ni/Ti/sub 2/N composite coating applied through electrodeposition and cathodic arc physical vapour deposition (CAPVD) to sintered NdFeB permanent magnets. The performance of composite coating was evaluated in simulated marine environment with the help of dc polarization techniques. The rate of coating degradation was also determined by employing ac electrochemical impedance spectroscopy (EIS). The coating morphology and surface chemistry were studied with scanning electron microscope (SEM). X-ray diffraction (XRD) was used for identification of component phases in the coating-substrate system. The results showed that the composite coating provided an adequately improved corrosion protection to the sintered NdFeB magnets in the simulated marine environment compared to the earlier reported ceramic and metallic coatings. The composite coating did not damage the magnetic properties of coating-substrate system that remained at par with the ceramic and nickel coating having copper interlayer. (author)

Investigations into the PbO-TeO2-B2O3 glass system

International Nuclear Information System (INIS)

Basariya, F.P.; Gugushvili, G.M.

1975-01-01

Based on the results of investigations of the system A-TeO 2 -B 2 O 3 and from the ternary phase diagram a region is determined of stable nonorganic glasses of the system PbO-TeO 2 -B 2 O 3 noncrystallizable at a temperature of 300 0 C and showing satisfactory chemical stability, as well as satisfactory isolation properties up to 300 0 C. On addition of an optimum amount of tellurium oxide one can obtain low-melting glasses with a temperature interval of 250-300 0 C. It is established that the substitution of PbO by TeO 2 or B 2 O 3 , or TeO 2 by B 2 O 3 leads to a decrease in the glass density. (author)

Preparation and characterization of amorphous SiO{sub 2} coatings deposited by mirco-arc oxidation on sintered NdFeB permanent magnets

Energy Technology Data Exchange (ETDEWEB)

Xu, J.L., E-mail: jlxu@nchu.edu.cn [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Xiao, Q.F.; Mei, D.D. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Zhong, Z.C., E-mail: zzhong2014@sina.com [The Institute for Rare Earth Magnetic Materials and Devices, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Tong, Y.X. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Zheng, Y.F., E-mail: yfzheng@pku.edu.cn [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Li, L. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China)

2017-03-15

Amorphous SiO{sub 2} coatings were prepared on sintered NdFeB magnets by micro-arc oxidation (MAO) in silicate solution. The surface and cross-sectional morphologies, element and phase composition, corrosion resistance and magnetic properties of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization test and physical properties measurements system (PPMS). The results showed that the surface morphologies of the coatings exhibited the “coral reef” like structure, different from the typical MAO porous structure. With increasing the voltages, the thickness of the coatings increased from 12.72 to 19.90 µm, the content of Si element increased, while the contents of Fe, Nd and P elements decreased. The coatings were mainly composed of amorphous SiO{sub 2} and a few amorphous Fe{sub 2}O{sub 3} and Nd{sub 2}O{sub 3}. The amorphous SiO{sub 2} coatings presented excellent thermal shock resistance, while the thermal shock resistance decreased with increasing the voltages. The corrosion resistance of the coatings increased with increasing the voltages, and it could be enhanced by one order of magnitude compared to the uncoated NdFeB magnets. The MAO coatings slightly decreased the magnetic properties of the NdFeB samples in different degrees. - Highlights: • Amorphous SiO{sub 2} coatings were prepared on sintered NdFeB magnets by micro-arc oxidation. • The coatings presented excellent thermal shock resistance. • The corrosion resistance could be enhanced by one order of magnitude. • The MAO coatings slightly decreased the magnetic properties of the NdFeB samples.

Tantalum coating on TiO{sub 2} nanotubes induces superior rate of matrix mineralization and osteofunctionality in human osteoblasts

Energy Technology Data Exchange (ETDEWEB)

Frandsen, Christine J.; Brammer, Karla S. [Materials Science and Engineering, University of California at San Diego, La Jolla, CA 92093 (United States); Noh, Kunbae [Corporate Research Institute, Cheil Industries, Inc., Gocheon-Dong, Uiwang-Si, Gyeonggi-Do, 437-711 (Korea, Republic of); Johnston, Gary [Materials Science and Engineering, University of California at San Diego, La Jolla, CA 92093 (United States); Jin, Sungho, E-mail: jin@ucsd.edu [Materials Science and Engineering, University of California at San Diego, La Jolla, CA 92093 (United States); Mechanical and Aerospace Engineering, University of California at San Diego, La Jolla, CA 92093 (United States)

2014-04-01

Nanostructured surface geometries have been the focus of a multitude of recent biomaterial research, and exciting findings have been published. However, only a few publications have directly compared nanostructures of various surface chemistries. The work herein directly compares the response of human osteoblast cells to surfaces of identical nanotube geometries with two well-known orthopedic biomaterials: titanium oxide (TiO{sub 2}) and tantalum (Ta). The results reveal that the Ta surface chemistry on the nanotube architecture enhances alkaline phosphatase activity, and promotes a ∼ 30% faster rate of matrix mineralization and bone-nodule formation when compared to results on bare TiO{sub 2} nanotubes. This study implies that unique combinations of surface chemistry and nanostructure may influence cell behavior due to distinctive physico-chemical properties. These findings are of paramount importance to the orthopedics field for understanding cell behavior in response to subtle alterations in nanostructure and surface chemistry, and will enable further insight into the complex manipulation of biomaterial surfaces. With increased focus in the field of orthopedic materials research on nanostructured surfaces, this study emphasizes the need for careful and systematic review of variations in surface chemistry in concurrence with nanotopographical changes. - Highlights: • A TiO{sub 2} nanotube surface structure was coated with tantalum. • Osteoblast cell response was compared between the tantalum coated and as-formed TiO{sub 2} nanotube surface. • We observed superior rates of bone matrix mineralization and osteoblast maturation on the tantalum coated nanotube surface.

Nanostructured layer-by-layer films containing phaeophytin-b: Electrochemical characterization for sensing purposes

Energy Technology Data Exchange (ETDEWEB)

Nunes Pauli, Gisele Elias [Departamento de Física, Universidade Federal de Santa Catarina, Florianópolis, SC 88040900 (Brazil); Araruna, Felipe B. [Núcleo de Pesquisa em Biodiversidade e Biotecnologia, BIOTEC, Campus Ministro Reis Velloso, CMRV, Universidade Federal do Piauí, UFPI, Parnaíba (Brazil); Eiras, Carla [Núcleo de Pesquisa em Biodiversidade e Biotecnologia, BIOTEC, Campus Ministro Reis Velloso, CMRV, Universidade Federal do Piauí, UFPI, Parnaíba (Brazil); Laboratório Interdisciplinar de Materiais Avançados, LIMAV, CCN, UFPI, Teresina, PI 64049-550 (Brazil); Leite, José Roberto S.A. [Núcleo de Pesquisa em Biodiversidade e Biotecnologia, BIOTEC, Campus Ministro Reis Velloso, CMRV, Universidade Federal do Piauí, UFPI, Parnaíba (Brazil); Chaves, Otemberg Souza; Filho, Severino Gonçalves Brito; Vanderlei de Souza, Maria de Fátima [Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, 58051-970 João Pessoa, Paraíba (Brazil); Chavero, Lucas Natálio; Sartorelli, Maria Luisa [Departamento de Física, Universidade Federal de Santa Catarina, Florianópolis, SC 88040900 (Brazil); and others

2015-02-01

This paper reports the study and characterization of a new platform for practical applications, where the use of phaeophytin-b (phaeo-b), a compound derived from chlorophyll, was characterized and investigated for sensing purposes. Modified electrodes with nanostructured phaeo-b films were fabricated via the layer-by-layer (LbL) technique, where phaeo-b was assembled with cashew gum, a polysaccharide, or with poly(allylamine) hydrochloride (PAH). The multilayer formation was investigated with UV–Vis spectroscopy by monitoring the absorption band associated to phaeo-b at approximately 410 nm, where distinct molecular interactions between the materials were verified. The morphology of the films was analyzed by atomic force microscopy (AFM). The electrochemical properties through redox behavior of phaeo-b were studied with cyclic voltammetry. The produced films were applied as sensors for hydrogen peroxide (H{sub 2}O{sub 2}) detection. In terms of sensing, the cashew/phaeo-b film exhibited the most promising result, with a fast response and broad linear range upon the addition of H{sub 2}O{sub 2}. This approach provides a simple and inexpensive method for development of a nonenzymatic electrochemical sensor for H{sub 2}O{sub 2}. - Highlights: • Potential applications of phaeophytin-b • Low-cost method to produce sensitive nanostructured films • Electrochemical sensor based on phaeophytin-b and cashew gum.

Laser coating of aluminum alloy EN AW 6082-T651 with TiB2 and TiC: Microstructure and mechanical properties

Science.gov (United States)

Ravnikar, Dunja; Dahotre, Narendra B.; Grum, Janez

2013-10-01

This paper deals with laser coating of ceramics by deposition of a precursor powder mixture of TiB2-TiC-Al on an EN AW 6082-T651 aluminum alloy. The resulting coating was studied by means of a microstructural and mechanical analysis. The coating has with TiC and TiB2 particles of various shapes and sizes embedded in an Al matrix, as well as being adherent and free of cracks with an average porosity lower than 2%. Microhardness in the coating is 40% higher than the uncoated alloy, while the microhardness in the laser melt zone and heat-affected zone dropped significantly. The wear test showed a great improvement in terms of the mass lost after the 30 min test. The three-point bending test was used to determine the flexural properties of the coated aluminum alloy. Higher content of TiB2 in ceramic components increases the flexural strength of the coated specimens, delaying the occurrence of the first crack in the coating or the occurrence of delamination. The measurements of residual stresses confirmed the presence of favorable compressive residual stresses in the surface coating. With depth, these stresses become tensile.

Investigation of Gamma and Neutron Shielding Parameters for Borate Glasses Containing NiO and PbO

OpenAIRE

Singh, Vishwanath P.; Badiger, N. M.

2014-01-01

The mass attenuation coefficients, μ/ρ, half-value layer, HVL, tenth-value layer, TVL, effective atomic numbers, ZPIeff, and effective electron densities, Ne,eff, of borate glass sample systems of (100-x-y) Na2B4O7 : xPbO : yNiO (where x and y=0, 2, 4, 6, 8, and 10 weight percentage) containing PbO and NiO, with potential gamma ray and neutron shielding applications, have been investigated. The gamma ray interaction parameters, μ/ρ, HVL, TVL, ZPIeff, and Ne,eff, were computed for photon energ...

Synthesis and Characterization of Nano-Hydroxyapatite/mPEG-b-PCL Composite Coating on Nitinol Alloy

Directory of Open Access Journals (Sweden)

Mohamadreza Etminanfar

2017-12-01

Full Text Available In this study the bioactivity of hydroxyapatite/poly(ε-caprolactone–poly(ethylene glycol bilayer coatings on Nitinol superelastic alloy was investigated. The surface of Nitinol alloy was activated by a thermo-chemical treatment and hydroxyapatite coating was electrodeposited on the alloy, followed by applying the polymer coating. The surface morphology of coatings was studied using FE-SEM and SEM. The data revealed that the hydroxyapatite coating is composed of one-dimensional nano sized flakes and the polymer coating is uniformly covered the sublayer. Also, High resolution TEM studies on the hydroxyapatite samples revealed that each flake contains nano-crystalline grains with a diameter of about 15 nm. The hydroxyapatite monolayer coating was rapidly covered by calcium phosphate crystals (Ca/P=1.7 after immersion in simulated body fluid confirming the bioactivity of the nanostructured flakes. However, the flakes were weak against applied external forces because of their ultra-fine thickness. Scratch test was applied on hydroxyapatite/polymer coating to evaluate delamination of the coating from substrate. It was shown that, the polymer coating has a great influence on toughening the hydroxyapatite coating. To assess the degradation effect of the polymer layer on hydroxyapatite coating, samples were immersed in phosphate-buffered saline at 37 ᵒC. SEM studies on the samples revealed that the beneath layer of hydroxyapatite appears after 72 h without any visible change in morphology. It seems that, application of a biodegradable polymer film on the nanostructured hydroxyapatite coating is a good way to support the coating during implantation processes

Synthesis, surface group modification of 3D MnV2O6 nanostructures and adsorption effect on Rhodamine B

International Nuclear Information System (INIS)

Zhang, Wanqun; Shi, Lei; Tang, Kaibin; Liu, Zhongping

2012-01-01

Highlights: ► Fabrication of urchin-like MnV 2 O 6 with oxygen-containing surface groups. ► Mn 0.5 V 2 O 5 ·nH 2 O as an intermediate product holds the key to the final products. ► 3D architectures of MnV 2 O 6 with oxygen-containing surface groups as sorbent. ► The sorbent shows a good adsorption ability. -- Abstract: Highly uniform 3D MnV 2 O 6 nanostructures modified by oxygen functional groups (-COO-) were successfully prepared in large quantities by an approach involving preparation of vanadyl ethylene glycolate as the precursor. The growth and self-assembly of MnV 2 O 6 nanobelts and nanorods could be readily tuned by additive species and quantities, which brought different morphologies and sizes to the final products. With a focus on the regulation of structure, the formation process of 3D architectures of MnV 2 O 6 by self-assembly of nanobelts was followed by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The consecutive processes of vanadyl ethylene glycolate and benzoyl peroxide assisted formation of layered structure Mn 0.5 V 2 O 5 ·nH 2 O, growth of aligned MnV 2 O 6 nanobelts, and oriented assembly were proposed for the growth mechanism. The band gap vs. different morphology was also studied. Optical characterization of these MnV 2 O 6 with different morphologies showed direct bandgap energies at 1.8–1.95 eV. The adsorption properties of 3D MnV 2 O 6 nanostructures synthesized under different conditions were investigated through the removal test of Rhodamine B in aqueous water, and the 3D nanostructures synthesized with 30 g L −1 benzoyl peroxide showed good adsorption capability of Rhodamine B.

Proton-induced nanorod melting in a coating obtained from the pulsed laser ablation of W{sub 2}B{sub 5}/B{sub 4}C

Energy Technology Data Exchange (ETDEWEB)

Tadadjeu Sokeng, I., E-mail: ifriky@tlabs.ac.za [Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville Campus, PO Box 1906, Bellville 7530 (South Africa); Electron Microscopy Unit, University of the Western Cape, Private bag x17, Bellville 7535 (South Africa); Ngom, B.D. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Laboratoire de Photonique et de Nanofrabrication, Groupes de physique du Solide et Sciences des Matriaux (GPSSM), Facult des sciences et Techniques, Universit Cheikh Anta Diop de Dakar (UCAD), B.P. 25114 Dakar-Fann, Dakar (Senegal); Cummings, F. [Electron Microscopy Unit, University of the Western Cape, Private bag x17, Bellville 7535 (South Africa); Kotsedi, L. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Msimanga, M. [iThemba LABS Gauten, Private Bag 11, WITS 2050, Johannesburg (South Africa); Maaza, M. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); and others

2015-02-01

Highlights: • Coatings from ablated B{sub 4}C/W{sub 2}B{sub 5} were irradiated with 900 keV protons. • Nanorod clusters were observed to melt and disperse. • Uniformly shaped nanorods were observed to grow. • Lateral diffusion of energy and lateral dispersion of matter were observed. - Abstract: Coatings obtained from pulsed laser ablated W{sub 2}B{sub 5}/B{sub 4}C were irradiated with 900keV protons at fluences ranging from about 1×10{sup 15}protons/cm{sup 2} to about 4×10{sup 15}protons/cm{sup 2}. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) were used to study the resulting structural effects. Clusters of nanorods were observed to disperse and reduce in number with increase in proton fluence. The atomic percentage of constituent elements were observed to vary with proton fluence, both within the nanorods and the film floor. Our results show that the structural effect of proton irradiation on the coating is lateral dispersion of matter.

Preparation and characterization of amorphous SiO2 coatings deposited by mirco-arc oxidation on sintered NdFeB permanent magnets

Science.gov (United States)

Xu, J. L.; Xiao, Q. F.; Mei, D. D.; Zhong, Z. C.; Tong, Y. X.; Zheng, Y. F.; Li, L.

2017-03-01

Amorphous SiO2 coatings were prepared on sintered NdFeB magnets by micro-arc oxidation (MAO) in silicate solution. The surface and cross-sectional morphologies, element and phase composition, corrosion resistance and magnetic properties of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization test and physical properties measurements system (PPMS). The results showed that the surface morphologies of the coatings exhibited the "coral reef" like structure, different from the typical MAO porous structure. With increasing the voltages, the thickness of the coatings increased from 12.72 to 19.90 μm, the content of Si element increased, while the contents of Fe, Nd and P elements decreased. The coatings were mainly composed of amorphous SiO2 and a few amorphous Fe2O3 and Nd2O3. The amorphous SiO2 coatings presented excellent thermal shock resistance, while the thermal shock resistance decreased with increasing the voltages. The corrosion resistance of the coatings increased with increasing the voltages, and it could be enhanced by one order of magnitude compared to the uncoated NdFeB magnets. The MAO coatings slightly decreased the magnetic properties of the NdFeB samples in different degrees.

Nanostructured hydrophobic DC sputtered inorganic oxide coating for outdoor glass insulators

Energy Technology Data Exchange (ETDEWEB)

Dave, V. [Department of Electrical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Institute Instrumentation Centre, Indian Institute of Technology, Roorkee, Roorkee 247667 (India); Gupta, H.O. [Department of Electrical Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Chandra, R., E-mail: ramesfic@gmail.com [Institute Instrumentation Centre, Indian Institute of Technology, Roorkee, Roorkee 247667 (India)

2014-03-01

Graphical abstract: - Highlights: • Deposition of contamination on outdoor glass insulators and its physical and economical consequences were discussed. • Synthesis of nanostructured hydrophobic HfO{sub 2} film on glass as a remedial measure by varying DC sputtering power. • Investigated and correlated structural, optical, electrical and hydrophobic properties of HfO{sub 2} films with respect to power. • Optimum results were obtained at a 50 W DC sputtering power. - Abstract: We report the structural, optical and electrical properties of nanostructured hydrophobic inorganic hafnium oxide coating for outdoor glass insulator using DC sputtering technique to combat contamination problem. The properties were studied as a function of DC power. The characterization of the films was done using X-ray diffraction, EDS, surface profilometer, AFM, impedance analyser and water contact angle measurement system. The DC power was varied from 30 to 60 W and found to have a great impact on the properties of hafnium oxide. All the deposited samples were polycrystalline with nanostructured hydrophobic surfaces. The intensity of crystallinity of the film was found to be dependent on sputtering power and hydrophobicity was correlated to the nanoscale roughness of the films. The optical property reveals 80% average transmission for all the samples. The refractive index was found in the range of 1.85–1.92, near to the bulk value. The band gap calculated from transmission data was >5.3 eV for all deposited samples ensuring dielectric nature of the films. Surface energy calculated by two methods was found minimum for the film deposited at 50 W sputtering power. The resistivity was also high enough (∼10{sup 4} Ω cm) to hinder the flow of leakage current through the film. The dielectric constant (ε) was found to be thickness dependent and also high enough (ε{sub max} = 23.12) to bear the large electric field of outdoor insulators.

Initial testing of TiB2 and TiC coated limiters in ISX-B

International Nuclear Information System (INIS)

Langley, R.A.; Emerson, R.A.; Whitley, J.B.; Mullendore, A.W.

1980-01-01

Low-Z coatings on graphite substrates have been developed for testing as limiters in the Impurity Study Experiment (ISX-B) tokamak. Laboratory and tokamak testings have been accomplished. The laboratory tests included thermal shock experiments by means of pulsed e-beam irradiation, arcing experiments, and hydrogen and xenon ion erosion experiments. The tokamak testing consisted of ohmically heated plasma exposures with energy depositions up to 10 kJ/discharge on the limiters. The coatings, applied by chemical vapor deposition, consisted of TiB 2 and TiC deposited on POCO graphite substrates. The limiter samples were interchanged through the use of a transfer chamber without atmospheric exposure of the ISX-B tokamak. Limiter samples were baked out in the transfer chamber before use in the tokamak. Provisions for both heating and cooling the limiter during tokamak discharge were made. Initial testing of the limiter samples consisted of exposure to only ohmically heated plasma; subsequent testing will be performed in neutral-beam-heated plasmas having up to 3 MW of injected power. Bulk and surface temperatures of the samples were measured to allow the determination of energy deposition. Extensive plasma and edge diagnostics were used to evaluate the effect of the limiter on the plasma (e.g. vacuum ultraviolet spectrometry to determine plasma impurity concentrations, Thomson scattering to determine Z effective, IR camera to measure limiter surface temperature, and laser fluorescence spectrometry to determine neutral impurity concentration and velocity distribution in the limiter region). (orig.)

Nanostructured superhydrophobic polysiloxane coating for high barrier and anticorrosion applications in marine environment.

Science.gov (United States)

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

2018-02-15

The use of epoxy and polyurethane coatings as marine topcoats, have been influenced by their inherent high surface energy property which increases their affinity to water and microorganisms. Thus, their susceptibility to degradation is enhanced. Because of this defect, recently, nanostructured hydrophobic and superhydrophobic polysiloxane coatings are being preferred as topcoats. But the appropriate nanoparticle size and matrix:filler ratio which provide guide for the design of desired topcoats are scarcely available. In view of this, a series of hydrophobic and superhydrophobic coatings were prepared by sol-gel process based on perfluorodecyltrichlorosilane (FDTS), different nanoZnO particles and poly(dimethylsiloxane) (PDMS):nanoZnO ratios. The liquid repellency, surface morphology and roughness of the coatings were conducted by use of contact angle goniometer, field emission scanning electron microscopy and atomic force microscopy, respectively. Additionally, the electrochemical and salt spray corrosion tests were conducted. According to the results, modifications of the coatings showed that anticorrosion performance was considerably influenced by the surface properties which were dependent on nanoZnO size and PDMS:nanoZnO ratio. Remarkably, the optimum effect was observed on the superhydrophobic coating based on 30 nm ZnO and 1:1 ratio. This displayed highest anticorrosion performance, and is therefore recommended as a guide for the design of marine topcoats. Copyright © 2017 Elsevier Inc. All rights reserved.

Superior critical current density obtained in MgB_2 bulks via employing carbon-coated boron and minor Cu addition

International Nuclear Information System (INIS)

Peng, Junming; Liu, Yongchang; Ma, Zongqing; Shahriar Al Hossain, M.; Xin, Ying; Jin, Jianxun

2016-01-01

Highlights: • Usage of carbon-coated boron leads to high level of homogeneous carbon doping. • Cu addition improves MgB_2 grain connectivity, leading to higher J_c at low fields. • Cu addition reduces MgO impurity, also contributing to the improvement of J_c. - Abstract: High performance Cu doped MgB_2 bulks were prepared by an in-situ method with carbon-coated amorphous boron as precursor. It was found that the usage of carbon-coated boron in present work leads to the formation of uniformly refined MgB_2 grains, as well as a high level of homogeneous carbon doping in the MgB_2 samples, which significantly enhance the J_c in both Cu doped and undoped bulks compared to MgB_2 bulks with normal amorphous boron precursor. Moreover, minor Cu can service as activator, and thus facilitates the growth of MgB_2 grains and improves crystallinity and grain connectivity, which can bring about the excellent critical current density (J_c) at self fields and low fields (the best values are 7 × 10"5 A/cm"2 at self fields, and 1 × 10"5 A/cm"2 at 2 T, 20 K, respectively). Simultaneously, minor Cu addition can reduce the amount of MgO impurity significantly, also contributing to the improvement of J_c at low fields. Our work suggests that Cu-activated sintering combined with employment of carbon-coated amorphous boron as precursor could be a promising technique to produce practical MgB_2 bulks or wires with excellent J_c on an industrial scale.

Nanostructured calcium phosphate coatings on magnesium alloys: characterization and cytocompatibility with mesenchymal stem cells

OpenAIRE

Iskandar, Maria Emil; Aslani, Arash; Tian, Qiaomu; Liu, Huinan

2015-01-01

This article reports the deposition and characterization of nanostructured calcium phosphate (nCaP) on magnesium–yttrium alloy substrates and their cytocompatibility with bone marrow derived mesenchymal stem cells (BMSCs). The nCaP coatings were deposited on magnesium and magnesium–yttrium alloy substrates using proprietary transonic particle acceleration process for the dual purposes of modulating substrate degradation and BMSC adhesion. Surface morphology and feature size were analyzed usin...

Fabrication of conductive metallized nanostructures from self-assembled amphiphilic triblock copolymer templates: Nanospheres, nanowires, nanorings

International Nuclear Information System (INIS)

Zhu Jintao; Jiang Wei

2007-01-01

Various metallized nanostructures (such as rings, wires with controllable lengths, spheres) have been successfully fabricated by coating metallic nanolayers onto soft nanotemplates through simple electroless methods. In particular, bimetallic nanostructures have been obtained by using simple methods. The multiple functional polymeric nanostructures were obtained through the self-assembly of polystyrene/poly(4-vinyl pyridine) triblock copolymer (P4VP-b-PS-b-P4VP) in selective media by changing the common solvent properties. By combining field emission scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) characterization, it was confirmed that polymer/metal and bimetallic (Au at Ag) core-shell nanostructures could be achieved by chemical metal deposition method

Electrocatalytic reduction of H{sub 2}O{sub 2} by Pt nanoparticles covalently bonded to thiolated carbon nanostructures

Energy Technology Data Exchange (ETDEWEB)

You, Jung-Min; Kim, Daekun [Department of Chemistry and Institute of Basic Science, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Jeon, Seungwon [Department of Chemistry and Institute of Basic Science, Chonnam National University, Gwangju 500-757 (Korea, Republic of)

2012-03-30

Highlights: Black-Right-Pointing-Pointer Novel thiolated carbon nanostructures - platinum nanoparticles [t-GO-C(O)-pt and t-MWCNT-C(O)-S-pt] have been synthesized, and [t-GO-C(O)-pt and t-MWCNT-C(O)-S-pt] denotes as t-GO-pt and t-MWCNT-Pt in manuscript, respectively. Black-Right-Pointing-Pointer The modified electrode denoted as PDDA/t-GO-pt/GCE was used for the electrochemical determination of H{sub 2}O{sub 2} for the first time. Black-Right-Pointing-Pointer The results show that PDDA/t-GO-pt nanoparticles have the promising potential as the basic unit of the electrochemical biosensors for the detection of H{sub 2}O{sub 2}. Black-Right-Pointing-Pointer The proposed H{sub 2}O{sub 2} biosensors exhibited wide linear ranges and low detection limits, giving fast responses within 10 s. - Abstract: Glassy carbon electrodes were coated with thiolated carbon nanostructures - multi-walled carbon nanotubes and graphene oxide. The subsequent covalent addition of platinum nanoparticles and coating with poly(diallydimethylammonium chloride) resulted in biosensors that detected hydrogen peroxide through its electrocatalytic reduction. The sensors were easily and quickly prepared and showed improved sensitivity to the electrocatalytic reduction of H{sub 2}O{sub 2}. The Pt nanoparticles covalently bonded to the thiolated carbon nanostructures were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. Cyclic voltammetry and amperometry were used to characterize the biosensors' performances. The sensors exhibited wide linear ranges and low detection limits, giving fast responses within 10 s, thus demonstrating their potential for use in H{sub 2}O{sub 2} analysis.

Alkali-etching growth of nest-like Ag@mTiO2 hierarchical nanostructures and their potential applications.

Science.gov (United States)

Zhang, Zongnan; Zhang, Haijiao

2017-06-01

Porous nanomaterials have attracted extensive interests in adsorption, catalysis, biosensors, and biomedicine due to their high surface area, well-defined pore structure and tunable pore size. However, how to obtain porous nanomaterials of desirable component and unique structure with multifunctionalities and synergetic properties is still a great challenge. In this work, a novel nest-like Ag@mTiO 2 hierarchical nanostructure with Ag nanoparticle as the core and a mesoporous crystalline TiO 2 as the protective shell was successfully prepared by layer-by-layer assembly technique and alkali-etching hydrothermal route. By simply changing the conditions of alkali etching, different nanostructures could be obtained, such as core-shell or rattle type. In the process, the thickness of coating silica layer and TiO 2 shell both played important roles for the formation of desired nanostructures. The as-prepared products had a large specific surface area of 301m 2 /g and a tailored TiO 2 outer shell. Raman spectra results showed perfect SERS signal of the tags enhanced and remained good stability even after one month. Doxycycline (Doxy) was chosen to evaluate their drug loading and controlled release properties. The results indicated that the obtained Ag@mTiO 2 nanoparticles exhibited good biocompatibility and excellent drug-loading capacity. Consequently, they are also expected to serve as ideal candidates for more potential applications including photocatalysis, drug controlled release, biosensor and cell imaging, etc. Copyright © 2017 Elsevier B.V. All rights reserved.

Photon mass attenuation coefficients of a silicon resin loaded with WO3, PbO, and Bi2O3 Micro and Nano-particles for radiation shielding

Science.gov (United States)

Verdipoor, Khatibeh; Alemi, Abdolali; Mesbahi, Asghar

2018-06-01

Novel shielding materials for photons based on silicon resin and WO3, PbO, and Bi2O3 Micro and Nano-particles were designed and their mass attenuation coefficients were calculated using Monte Carlo (MC) method. Using lattice cards in MCNPX code, micro and nanoparticles with sizes of 100 nm and 1 μm was designed inside a silicon resin matrix. Narrow beam geometry was simulated to calculate the attenuation coefficients of samples against mono-energetic beams of Co60 (1.17 and 1.33 MeV), Cs137 (663.8 KeV), and Ba133 (355.9 KeV). The shielding samples made of nanoparticles had higher mass attenuation coefficients, up to 17% relative to those made of microparticles. The superiority of nano-shields relative to micro-shields was dependent on the filler concentration and the energy of photons. PbO, and Bi2O3 nanoparticles showed higher attenuation compared to WO3 nanoparticles in studied energies. Fabrication of novel shielding materials using PbO, and Bi2O3 nanoparticles is recommended for application in radiation protection against photon beams.

Uranium enrichment reduction in the Prototype Gen-IV sodium-cooled fast reactor (PGSFR) with PBO reflector

Energy Technology Data Exchange (ETDEWEB)

Hartanto, Donny; Kim, Chi Hyung; Kim, Yong Hee [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon (Korea, Republic of)

2016-04-15

The Korean Prototype Gen-IV sodium-cooled fast reactor (PGSFR) is supposed to be loaded with a relatively-costly low-enriched U fuel, while its envisaged transuranic fuels are not available for transmutation. In this work, the U-enrichment reduction by improving the neutron economy is pursued to save the fuel cost. To improve the neutron economy of the core, a new reflector material, PbO, has been introduced to replace the conventional HT9 reflector in the current PGSFR core. Two types of PbO reflectors are considered: one is the conventional pin-type and the other one is an inverted configuration. The inverted PbO reflector design is intended to maximize the PbO volume fraction in the reflector assembly. In addition, the core radial configuration is also modified to maximize the performance of the PbO reflector. For the baseline PGSFR core with several reflector options, the U enrichment requirement has been analyzed and the fuel depletion analysis is performed to derive the equilibrium cycle parameters. The linear reactivity model is used to determine the equilibrium cycle performances of the core. Impacts of the new PbO reflectors are characterized in terms of the cycle length, neutron leakage, radial power distribution, and operational fuel cost.

Microstructure and Properties of (TiB2 + NiTi)/Ti Composite Coating Fabricated by Laser Cladding

Science.gov (United States)

Lin, Yinghua; Lei, Yongping; Fu, Hanguang; Lin, Jian

2015-10-01

Agglomerated TiB2 particle and network-like structure-reinforced titanium matrix composite coatings were prepared by laser cladding of the Ni + TiB2 + Ti preplaced powders on Ti-6Al-4V alloy. The network-like structure mainly consisted of NiTi and Ni3Ti. Through the experiment, it was found that the size of agglomerated particle gradually decreased with the increase of Ti content, but the number of the network-like structure first increased and then disappeared. In-situ reaction competition mechanism and the formation of network-like structure were discussed. The average micro-hardness gradually decreased with the increase of Ti content, but the average fracture toughness gradually increased. Meanwhile, the wear resistance of the coatings is higher than that of the substrate, but the wear loss of the coatings is gradually increased with the increase of Ti content.

Nanocoatings size effect in nanostructured films

CERN Document Server

Aliofkhazraei, Mahmood

2014-01-01

Size effect in structures has been taken into consideration over the last years. In comparison with coatings with micrometer-ranged thickness, nanostructured coatings usually enjoy better and appropriate properties, such as strength and resistance. These coatings enjoy unique magnetic properties and are used with the aim of producing surfaces resistant against erosion, lubricant system, cutting tools, manufacturing hardened sporadic alloys, being resistant against oxidation and corrosion. This book reviews researches on fabrication and classification of nanostructured coatings with focus on size effect in nanometric scale. Size effect on electrochemical, mechanical and physical properties of nanocoatings are presented.

Effect of Anti-Sticking Nanostructured Surface Coating on Minimally Invasive Electrosurgical Device in Brain.

Science.gov (United States)

Cheng, Han-Yi; Ou, Keng-Liang; Chiang, Hsi-Jen; Lin, Li-Hsiang

2015-10-01

The purpose of the present study was to examine the extent of thermal injury in the brain after the use of a minimally invasive electrosurgical device with a nanostructured copper-doped diamond-like carbon (DLC-Cu) surface coating. To effectively utilize an electrosurgical device in clinical surgery, it is important to decrease the thermal injury to the adjacent tissues. The surface characteristics and morphology of DLC-Cu thin film was evaluated using a contact angle goniometer, scanning electron microscopy, and atomic force microscopy. Three-dimensional biomedical brain models were reconstructed using magnetic resonance images to simulate the electrosurgical procedure. Results indicated that the temperature was reduced significantly when a minimally invasive electrosurgical device with a DLC-Cu thin film coating (DLC-Cu-SS) was used. Temperatures decreased with the use of devices with increasing film thickness. Thermographic data revealed that surgical temperatures in an animal model were significantly lower with the DLC-Cu-SS electrosurgical device compared to an untreated device. Furthermore, the DLC-Cu-SS device created a relatively small region of injury and lateral thermal range. As described above, the biomedical nanostructured film reduced excessive thermal injury with the use of a minimally invasive electrosurgical device in the brain.

Synthesis and properties of nanostructured dense LaB6 cathodes by arc plasma and reactive spark plasma sintering

International Nuclear Information System (INIS)

Zhou Shenlin; Zhang Jiuxing; Liu Danmin; Lin Zulun; Huang Qingzhen; Bao Lihong; Ma Ruguang; Wei Yongfeng

2010-01-01

Nanostructured polycrystalline LaB 6 ceramics were prepared by the reactive spark plasma sintering method, using boron nanopowders and LaH 2 powders with a particle size of about 30 nm synthesized by hydrogen dc arc plasma. The reaction mechanism of sintering, crystal structure, microstructure, grain orientations and properties of the materials were investigated using differential scanning calorimetry, X-ray diffraction, Neutron powder diffraction, Raman spectroscopy, transmission electron microscopy and electron backscattered diffraction. It is shown that nanostructured dense LaB 6 with a fibrous texture can be fabricated by SPS at a pressure of 80 MPa and temperature of 1300 deg. C for 5 min. Compared with the coarse polycrystalline LaB 6 prepared by traditional methods, the nanostructured LaB 6 bulk possesses both higher mechanical and higher thermionic emission properties. The Vickers hardness was 22.3 GPa, the flexural strength was 271.2 MPa and the maximum emission current density was 56.81 A cm -2 at a cathode temperature of 1600 deg. C.

Microstructure and Wear Resistance of Laser-Clad (Co, Ni61.2B26.2Si7.8Ta4.8 Coatings

Directory of Open Access Journals (Sweden)

Luan Zhang

2017-10-01

Full Text Available It has been reported that a quaternary Co61.2B26.2Si7.8Ta4.8 alloy is a good glass former and can be laser-clad to an amorphous composite coating with superior hardness and wear resistance. In this paper, alloys with varying Ni contents to substitute for Co are coated on the surface of #45 carbon steel using a 5-kW CO2 laser source for the purpose of obtaining protective coatings. In contrast to the quaternary case, the clad layers are characterized by a matrix of α-(Fe, Co, Ni solid solution plus CoB, Co3B, and Co3Ta types of precipitates. The cladding layer is divided into four regions: Near-surface dendrites, α-(Fe, Co, Ni solid solution plus dispersed particles in the middle zone, columnar bonding zone, and heat-affected area that consists of martensite. The hardness gradually decreases with increasing Ni content, and the maximum hardness occurs in the middle zone. Both the friction coefficient and wear volume are minimized in the alloy containing 12.2% Ni. Compared with the previous cobalt-based quaternary alloy Co61.2B26.2Si7.8Ta4.8, the addition of the Ni element reduces the glass-forming ability and henceforth the hardness and wear resistance of the clad layers.

Modified wound dressing with phyto-nanostructured coating to prevent staphylococcal and pseudomonal biofilm development

OpenAIRE

Anghel, Ion; Holban, Alina Maria; Grumezescu, Alexandru Mihai; Andronescu, Ecaterina; Ficai, Anton; Anghel, Alina Georgiana; Maganu, Maria; Laz?r, Veronica; Chifiriuc, Mariana Carmen

2012-01-01

This paper reports a newly fabricated nanophyto-modified wound dressing with microbicidal and anti-adherence properties. Nanofluid-based magnetite doped with eugenol or limonene was used to fabricate modified wound dressings. Nanostructure coated materials were characterized by TEM, XRD, and FT-IR. For the quantitative measurement of biofilm-embedded microbial cells, a culture-based method for viable cell count was used. The optimized textile dressing samples proved to be more resistant to st...

Relationship between the mechanical properties of epoxy/PMMA-b-PnBA-b-PMMA block copolymer blends and their three-dimensional nanostructures

Directory of Open Access Journals (Sweden)

H. Kishi

2017-10-01

Full Text Available Nanostructures of diglycidyl ether of bisphenol-A epoxy/poly(methyl methacrylate-b-poly(n-butyl acrylate-b-poly(methyl methacrylate (PMMA-b-PnBA-b-PMMA triblock copolymer (BCP blends were studied in relation to their mechanical properties. Three types of self-assembled nanostructures, such as spheres, random cylinders, and curved lamella, were controlled in phenol novolac-cured epoxy blends with a wide range of BCP content. Three types of nanostructures were observed using two-dimensional and three-dimensional transmission electron microscopy (TEM. The 3D-TEM, dynamic viscoelastic analyses, and theoretical model on the elastic modulus clarified that the spheres and the random cylinders, consisted of epoxy-immiscible PnBA phases, were discontinuously dispersed in the epoxy matrix. In contrast, the curved lamella formed co-continuous nanostructure, in which both the PnBA and epoxy phases formed continuous channels. The fracture toughness (critical strain energy release rate, GIC and the flexural moduli of elasticity (E of the cured blends were evaluated for various amounts of BCP content. The highest GIC was obtained from the random cylindrical nanostructured blends in the three types of nanostructures with the same PnBA content. The lowest E was obtained for the curved lamella with co-continuous nanostructures. The details of deformation and fracture events were observed using optical and electron microscopy, and the mechanical properties are discussed in relation to the nanostructures.

Preparation of ultra-fine powders from polysaccharide-coated solid lipid nanoparticles and nanostructured lipid carriers by innovative nano spray drying technology.

Science.gov (United States)

Wang, Taoran; Hu, Qiaobin; Zhou, Mingyong; Xue, Jingyi; Luo, Yangchao

2016-09-10

In this study, five polysaccharides were applied as natural polymeric coating materials to prepare solid lipid nanoparticles (SLN) and nanostructure lipid carriers (NLC), and then the obtained lipid colloidal particles were transformed to solid powders by the innovative nano spray drying technology. The feasibility and suitability of this new technology to generate ultra-fine lipid powder particles were evaluated and the formulation was optimized. The spray dried SLN powder exhibited the aggregated and irregular shape and dimension, but small, uniform, well-separated spherical powder particles of was obtained from NLC. The optimal formulation of NLC was prepared by a 20-30% oleic acid content with carrageenan or pectin as coating material. Therefore, nano spray drying technology has a potential application to produce uniform, spherical, and sub-microscale lipid powder particles when the formulation of lipid delivery system is appropriately designed. Copyright © 2016 Elsevier B.V. All rights reserved.

Phase Constituents and Microstructure of Ti3Al/Fe3Al + TiN/TiB2 Composite Coating on Titanium Alloy

Science.gov (United States)

Li, Jianing; Chen, Chuanzhong; Zhang, Cuifang

Laser cladding of the Fe3Al + B4C/TiN + Al2O3 pre-placed powders on the Ti-6Al-4V alloy can form the Ti3Al/Fe3Al + TiN/TiB2 composite coating, which improved the wear resistance of the Ti-6Al-4V alloy surface. In this study, the Ti3Al/Fe3Al + TiN/TiB2 composite coating has been researched by means of X-ray diffraction and scanning electron microscope. It was found that during the laser cladding process, Al2O3 can react with TiB2, leading to the formations of Ti3Al and B. This principle can be used to improve the Fe3Al + B4C/TiN laser-cladded coating on the Ti-6Al-4V alloy. Furthermore, during the cladding process, C consumed the oxygen in Fe3Al + B4C /TiN + Al2O3 molten pool, which retarded the productions of the redundant metal oxides.

Phase-Separated, Epitaxial, Nanostructured LaMnO₃+MgO Composite Cap Layer Films for Propagation of Pinning Defects in YBa₂Cu₃O_7-x Coated Conductors

Energy Technology Data Exchange (ETDEWEB)

Wee, Sung Hun [ORNL; Shin, Junsoo [ORNL; Cantoni, Claudia [ORNL; Meyer III, Harry M [ORNL; Cook, Sylvester W [ORNL; Zuev, Yuri L [ORNL; Specht, Eliot D [ORNL; Xiong, Xuming [ORNL; Paranthaman, Mariappan Parans [ORNL; Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York; Goyal, Amit [ORNL

2009-01-01

Nanostructural modulation in the cap layer used in coated conductors can be a potential source for nucleating microstructural defects into the superconducting layer for improving the flux-pinning. We report on the successful fabrication of phase separated, epitaxial, nanostructured films comprised of LaMnO{sub 3} (LMO) and MgO via pulsed laser deposition (PLD) on biaxially-textured MgO metallic templates with a LMO buffer layer. Scanning Auger compositional mapping and transmission electron microscopy cross sectional images confirm the nanoscale, spatial modulation corresponding to the nanostructured phase separation in the film. YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} films (0.8 {micro}m thick) grown using PLD on such phase separated, nanostructured cap layers show reduced field dependence of the critical current density with an ? value of -0.38 (in J{sub c}-H{sup -{alpha}}).

Regularities of Filamentary Channels Formation During Formation of Nanostructured Non-Metallic Inorganic Coatings in Microplasma Galvanostatic Mode in Solutions

Science.gov (United States)

Mamaev, A. I.; Mamaeva, V. A.; Kolenchin, N. F.; Chubenko, A. K.; Kovalskaya, Ya. B.; Konstantinova, T. A.; Dolgova, Yu. N.; Beletskaya, E. Yu.

2016-04-01

This paper presents the theoretical models describing the growth of filamentary channels of nanostructured non-metallic coatings formed by anodizing and microplasma oxidation. The authors identified dependences of the number of pores on the coating thickness. The paper presents graphic dependences of the number of filamentary channels on the process time and the coating thickness. These dependences allow calculating through and surface porosity, and in cases, when the pores are filled with functional material, they allow calculating the concentration distribution of this functional material throughout the coating thickness. The theoretical models enhance our understanding of the nature of anode processes and can be used to describe and forecast the growth and filling of porous coatings, so they can also be used to create functional and bioactive materials.

Improvement of interfacial adhesion and nondestructive damage evaluation for plasma-treated PBO and Kevlar fibers/epoxy composites using micromechanical techniques and surface wettability.

Science.gov (United States)

Park, Joung-Man; Kim, Dae-Sik; Kim, Sung-Ryong

2003-08-15

Comparison of interfacial properties and microfailure mechanisms of oxygen-plasma treated poly(p-phenylene-2,6-benzobisoxazole (PBO, Zylon) and poly(p-phenylene terephthalamide) (PPTA, Kevlar) fibers/epoxy composites were investigated using a micromechanical technique and nondestructive acoustic emission (AE). The interfacial shear strength (IFSS) and work of adhesion, Wa, of PBO or Kevlar fiber/epoxy composites increased with oxygen-plasma treatment, due to induced hydrogen and covalent bondings at their interface. Plasma-treated Kevlar fiber showed the maximum critical surface tension and polar term, whereas the untreated PBO fiber showed the minimum values. The work of adhesion and the polar term were proportional to the IFSS directly for both PBO and Kevlar fibers. The microfibril fracture pattern of two plasma-treated fibers appeared obviously. Unlike in slow cooling, in rapid cooling, case kink band and kicking in PBO fiber appeared, whereas buckling in the Kevlar fiber was observed mainly due to compressive and residual stresses. Based on the propagation of microfibril failure toward the core region, the number of AE events for plasma-treated PBO and Kevlar fibers increased significantly compared to the untreated case. The results of nondestructive AE were consistent with microfailure modes.

Experimental Study of Liquidus of the "FeO"-SiO2-PbO Slags in Equilibrium with Air and with Metallic Lead

Science.gov (United States)

Shevchenko, Maksym; Hidayat, Taufiq; Hayes, Peter C.; Jak, Evgueni

Limited data are available on phase equilibria of the "FeO"-SiO2-PbO slag system at conditions used in the lead smelting due to difficulties from lead vaporization and interactions with metal and ceramic crucibles. Recently experimental procedures have been developed and successfully applied to complex industrial slag-metal-matte systems involving high temperature equilibration on a primary phase substrate and rapid quenching followed by the electron probe X-ray microanalysis. The liquidus isotherms and invariant lines in the "FeO"-SiO2-PbO slag system in equilibrium with air and with metallic lead have been constructed. Preliminary data compared to the FactSage package predictions demonstrate differences in some aspects, indicating the possibility for further improvement of the thermodynamic database. The present work is a part of the integrated experimental and thermodynamic modelling research program on multi-phase lead systems in support of the optimization and development of complex lead smelting, refining and recycling technologies.

Nanostructured Double Hydrophobic Poly(Styrene-b-Methyl Methacrylate) Block Copolymer Membrane Manufactured Via Phase Inversion Technique

KAUST Repository

Karunakaran, Madhavan; Shevate, Rahul; Peinemann, Klaus-Viktor

2016-01-01

In this paper, we demonstrate the formation of nanostructured double hydrophobic poly(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymer membranes via state-of-the-art phase inversion technique. The nanostructured membrane morphologies are tuned by different solvent and block copolymer compositions. The membrane morphology has been investigated using FESEM, AFM and TEM. Morphological investigation shows the formation of both cylindrical and lamellar structures on the top surface of the block copolymer membranes. The PS-b-PMMA having an equal block length (PS160K-b-PMMA160K) exhibits both cylindrical and lamellar structures on the top layer of the asymmetric membrane. All membranes fabricated from PS160K-b-PMMA160K shows an incomplete pore formation in both cylindrical and lamellar morphologies during the phase inversion process. However, PS-b-PMMA (PS135K-b-PMMA19.5K) block copolymer having a short PMMA block allowed us to produce open pore structures with ordered hexagonal cylindrical pores during the phase inversion process. The resulting PS-b-PMMA nanostructured block copolymer membranes have pure water flux from 105-820 l/m2.h.bar and 95% retention of PEG50K

Nanostructured Double Hydrophobic Poly(Styrene-b-Methyl Methacrylate) Block Copolymer Membrane Manufactured Via Phase Inversion Technique

KAUST Repository

Karunakaran, Madhavan

2016-03-11

In this paper, we demonstrate the formation of nanostructured double hydrophobic poly(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymer membranes via state-of-the-art phase inversion technique. The nanostructured membrane morphologies are tuned by different solvent and block copolymer compositions. The membrane morphology has been investigated using FESEM, AFM and TEM. Morphological investigation shows the formation of both cylindrical and lamellar structures on the top surface of the block copolymer membranes. The PS-b-PMMA having an equal block length (PS160K-b-PMMA160K) exhibits both cylindrical and lamellar structures on the top layer of the asymmetric membrane. All membranes fabricated from PS160K-b-PMMA160K shows an incomplete pore formation in both cylindrical and lamellar morphologies during the phase inversion process. However, PS-b-PMMA (PS135K-b-PMMA19.5K) block copolymer having a short PMMA block allowed us to produce open pore structures with ordered hexagonal cylindrical pores during the phase inversion process. The resulting PS-b-PMMA nanostructured block copolymer membranes have pure water flux from 105-820 l/m2.h.bar and 95% retention of PEG50K

Coatings of nanostructured pristine graphene-IrOx hybrids for neural electrodes: Layered stacking and the role of non-oxygenated graphene

Energy Technology Data Exchange (ETDEWEB)

Pérez, E. [Institut Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193, Bellaterra, Barcelona (Spain); Lichtenstein, M.P.; Suñol, C. [Institut d' Investigacions Biomèdiques de Barcelona (IIBB-CSIC), Institut d' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), c/Rosselló 161, 08036 Barcelona (Spain); Casañ-Pastor, N., E-mail: nieves@icmab.es [Institut Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193, Bellaterra, Barcelona (Spain)

2015-10-01

The need to enhance charge capacity in neural stimulation-electrodes is promoting the formation of new materials and coatings. Among all the possible types of graphene, pristine graphene prepared by graphite electrochemical exfoliation, is used in this work to form a new nanostructured IrOx–graphene hybrid (IrOx–eG). Graphene is stabilized in suspension by IrOx nanoparticles without surfactants. Anodic electrodeposition results in coatings with much smaller roughness than IrOx–graphene oxide. Exfoliated pristine graphene (eG), does not electrodeposit in absence of iridium, but IrOx-nanoparticle adhesion on graphene flakes drives the process. IrOx–eG has a significantly different electronic state than graphene oxide, and different coordination for carbon. Electron diffraction shows the reflection features expected for graphene. IrOx 1–2 nm cluster/nanoparticles are oxohydroxo-species and adhere to 10 nm graphene platelets. eG induces charge storage capacity values five times larger than in pure IrOx, and if calculated per carbon atom, this enhancement is one order magnitude larger than the induced by graphene oxide. IrOx–eG coatings show optimal in vitro neural cell viability and function as cell culture substrates. The fully straightforward electrochemical exfoliation and electrodeposition constitutes a step towards the application of graphene in biomedical systems, expanding the knowledge of pristine graphene vs. graphene oxide, in bioelectrodes. - Highlights: • Pristine Graphene is incorporated in coatings as nanostructured IrOx–eG hybrid. • IrOx-nanoparticles drive the electrodeposition of graphene. • Hybrid CSC is one order of magnitude the charge capacity of IrOx. • Per carbon atom, the CSC increase is 35 times larger than for graphene oxide. • Neurons are fully functional on the coating.

Characterization and study of the electrical and dielectric properties of SrBi_4Ti_4O_1_5 (SBTi) added PbO and V_2O_5 for radio frequency (RF) applications

International Nuclear Information System (INIS)

Rodrigues Junior, C.A.; Freitas, D.B.; Fernandes, T.S.M.; Sombra, A.S.B.

2011-01-01

The objective of this work was to study the dielectric and electric properties in radio frequency (RF) of the compound SrBi_4Ti_4O_1_5 (SBTi) added with PbO and V_2O_5. The SBT ceramic, perovskite with cation deficiency A_5B_4O_1_5, was prepared by the solid state reaction method and then added with PbO (0, 2, 5, 10 and 15% by weight) and with V_2O_3 (in the range of 0.2 %, 5%, 10% and 15% by weight). The samples were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A study based on Impedance Spectroscopy was also performed. X-ray analysis indicates that all samples have orthorhombic crystalline system and spatial group A21am. The quantitative phase analysis performed by the Rietveld refinement confirmed the crystal structure with net parameter a = 5.4400 Å, b = 5.4326 Å and c = 41.2169 Å. Scanning electron microscopy shows globular and crystal shaped grains, with a certain uniformity in the grain size that is very small, between 1 and 2 μm approximately. Dielectric properties: dielectric constant (K ') and dielectric loss (tang δ) were measured at room temperature in the 40 Hz - 110 MHz frequency range, as well as the a.c. conductivity and have very relevant properties, such as dielectric constant above 50, for the production of possible capacitive devices. All samples were investigated for possible applications in electronic circuits

Controllable synthesis and defect-dependent photoluminescence properties of In2O3 nanostructures prepared by PVD

Science.gov (United States)

Jin, Changqing; Wei, Yongxing; Peterson, George; Zhu, Kexin; Jian, Zengyun

2017-05-01

In2O3 nanostructures were successfully synthesized via physical vapor deposition (PVD). It was found that the morphology of nanostuctures could be controlled by manipulation of the synthesis temperature, growth time, use of a Au-catalyst, selection of substrate material, and vapor pressure. A higher synthesis temperature is more favorable for the formation of 1D nanostructures. An increased growth time increased the width and length of the 1D nanostructures. Through the use of a Au-catalyst coated Si (1 0 0) substrate, we were able to preferentially synthesize (1 0 0) In2O3 nanostructures, even at lower growth temperatures. This research shows that a Au-catalyst is necessary for the formation of one-dimensional (1D) In2O3 nanostructures. Three dimensional (3D) octahedral nanoparticles are resultant from a Au-free Si (1 0 0) substrate. Al2O3 (1 0 0) substrates were found to be energetically favorable for the synthesis of nanofilms, not 1D nanostructures, regardless of the presence of Au-catalyst. The photoluminescence curves indicate that the defect related luminescence is not a function of morphology, but rather the ratio of the partial vapor pressures of the constituent elements (In and O), which were controlled by the growth pressure.

Nanostructured antistatic and antireflective thin films made of indium tin oxide and silica over-coat layer

Science.gov (United States)

Cho, Young-Sang; Hong, Jeong-Jin; Yang, Seung-Man; Choi, Chul-Jin

2010-08-01

Stable dispersion of colloidal indium tin oxide nanoparticles was prepared by using indium tin oxide nanopowder, organic solvent, and suitable dispersants through attrition process. Various comminution parameters during the attrition step were studied to optimize the process for the stable dispersion of indium tin oxide sol. The transparent and conductive films were fabricated on glass substrate using the indium tin oxide sol by spin coating process. To obtain antireflective function, partially hydrolyzed alkyl silicate was deposited as over-coat layer on the pre-fabricated indium tin oxide film by spin coating technique. This double-layered structure of the nanostructured film was characterized by measuring the surface resistance and reflectance spectrum in the visible wavelength region. The final film structure was enough to satisfy the TCO regulations for EMI shielding purposes.

Nanostructured ‘Anastacia’ flowers for Zn coating by electrodepositing ZnO at room temperature

Energy Technology Data Exchange (ETDEWEB)

Alves, Marta M., E-mail: martamalves@tecnico.ulisboa.pt [ICEMS Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1049-001, Lisboa (Portugal); Santos, Catarina F.; Carmezim, Maria J. [ICEMS Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1049-001, Lisboa (Portugal); EST Setúbal, DEM, Instituto Politécnico de Setúbal, Campus IPS, 2910 Setúbal (Portugal); Montemor, Maria F. [ICEMS Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1049-001, Lisboa (Portugal)

2015-03-30

Graphical abstract: - Highlights: • Functional coating of Zn with ZnO ‘Anastacia’ flowers. • Flowers are composed by nano-hexagonal units of single-crystal wurtzite ZnO. • The growth mechanism of these flowers is discussed. • Room temperature yield cost-effective electrodeposited ZnO ‘Anastacia’ flowers. - Abstract: Functional coatings composed of ZnO, a new flowered structured denominated as ‘Anastacia’ flowers, were successfully obtained through a facile and green one-step electrodeposition approach on Zn substrate. Electrodeposition was performed at constant cathodic potential, in Zn(NO{sub 3}){sub 2} aqueous solution, at pH 6 and at room temperature. The resulting ZnO thin uniform layer, with an average thickness of 300 nm, bearing top 3D hierarchical nanostructures that compose ‘Anastacia’ flowers, was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman. The results reveal a nano-architecture structure composed by nano-hexagonal units of single-crystal wurtzite ZnO structure with a [0 0 0 1] growth direction along the longitudinal particles axis. Other morphological features, sphere-like, rod-like and random distributed hexagons were also obtained by varying the electrodeposition time as observed by SEM. The Raman spectroscopy revealed the typical peak of ZnO wurtzite for all the obtained morphologies. Coatings wettability was studied and the different morphologies display distinct water contact angles with the ‘Anastacia’ flowers coating showing a wettability of 110°. These results pave the way for simple and low-cost routes for the production of novel functionalized coatings of ZnO over Zn, with potential for biomedical devices.

Nanostructured ‘Anastacia’ flowers for Zn coating by electrodepositing ZnO at room temperature

International Nuclear Information System (INIS)

Alves, Marta M.; Santos, Catarina F.; Carmezim, Maria J.; Montemor, Maria F.

2015-01-01

Graphical abstract: - Highlights: • Functional coating of Zn with ZnO ‘Anastacia’ flowers. • Flowers are composed by nano-hexagonal units of single-crystal wurtzite ZnO. • The growth mechanism of these flowers is discussed. • Room temperature yield cost-effective electrodeposited ZnO ‘Anastacia’ flowers. - Abstract: Functional coatings composed of ZnO, a new flowered structured denominated as ‘Anastacia’ flowers, were successfully obtained through a facile and green one-step electrodeposition approach on Zn substrate. Electrodeposition was performed at constant cathodic potential, in Zn(NO 3 ) 2 aqueous solution, at pH 6 and at room temperature. The resulting ZnO thin uniform layer, with an average thickness of 300 nm, bearing top 3D hierarchical nanostructures that compose ‘Anastacia’ flowers, was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman. The results reveal a nano-architecture structure composed by nano-hexagonal units of single-crystal wurtzite ZnO structure with a [0 0 0 1] growth direction along the longitudinal particles axis. Other morphological features, sphere-like, rod-like and random distributed hexagons were also obtained by varying the electrodeposition time as observed by SEM. The Raman spectroscopy revealed the typical peak of ZnO wurtzite for all the obtained morphologies. Coatings wettability was studied and the different morphologies display distinct water contact angles with the ‘Anastacia’ flowers coating showing a wettability of 110°. These results pave the way for simple and low-cost routes for the production of novel functionalized coatings of ZnO over Zn, with potential for biomedical devices

Initial testing of coated limiters in ISX-B

International Nuclear Information System (INIS)

Langley, R.A.; Emerson, L.C.; Whitley, J.B.; Mullendore, A.W.

1980-01-01

Low-Z coatings on graphite substrates have been developed for testing as limiters in the Impurity Study Experiment (ISX-B) tokamak. Laboratory and tokamak testings have been accomplished. The laboratory tests included thermal shock experiments by means of pulsed e-beam irradiation, arcing experiments, and hydrogen and xenon ion erosion experiments. The tokamak testing consisted of ohmically heated plasma exposures with energy depositions up to 10 kJ/discharge on the limiters. The coatings, applied by chemical vapor deposition, consisted of TiB 2 and TiC deposited on POCO graphite substrates

Synthesis of One Dimensional Li2MoO4 Nanostructures and Their Electrochemical Performance as Anode Materials for Lithium-ion Batteries

International Nuclear Information System (INIS)

Liu, Xudong; Zhao, Yanming; Dong, Youzhong; Fan, Qinghua; Kuang, Quan; Liang, Zhiyong; Lin, Xinghao; Han, Wei; Li, Qidong; Wen, Mingming

2015-01-01

Highlights: • One dimensional Li 2 MoO 4 nanostructures including nanorods and nanotubes have been successfully fabricated via a simple sol-gel method firstly. • Possible crystal formation mechanisms are proposed for these one dimensional Li 2 MoO 4 nanostructures. • These one dimensional Li 2 MoO 4 nanostructure electrode materials present outstanding rate abilities and cycle capabilities in electrochemical performance compared to the carbon-free powder sample when evaluated as anode materials for Lithium-ion batteries. • The carbon-coated Li 2 MoO 4 nanotube electrode improves the charging/discharging capacities of graphite even after applying 60 cycles at very high current density. - Abstract: One dimensional Li 2 MoO 4 nanostructures including nanorods and nanotubes have been successfully fabricated via a simple sol-gel method adding Li 2 CO 3 and MoO 3 powders into distilled water with citric acid as an assistant agent and carbon source. Our experimental results show that the formation of the one dimensional nanostructure morphology is evaporation and crystallization process with self-adjusting into a rod-like hexagonal cross-section structure, while the citric acid played an important role during the formation of Li 2 MoO 4 nanotubes under the acidic environment by capping, stabilizing the {1010} facet of Li 2 MoO 4 structure and controlling the concentration of H + (pH value) of the aqueous solution. Finally, basic electrochemical performance of these one dimensional Li 2 MoO 4 nanostructures including nanorods and nanotubes evaluated as anode materials for lithium-ion batteries (LIBs) are discussed, for comparison, the properties of carbon-free powder sample synthesized by solid-state reaction are also displayed. Experimental results show that different morphology and carbon-coating on the surface have an important influence on electrochemical performance

Carbon-coated Si nanoparticles/reduced graphene oxide multilayer anchored to nanostructured current collector as lithium-ion battery anode

Energy Technology Data Exchange (ETDEWEB)

Liu, Zhengjiao; Guo, Pengqian; Liu, Boli; Xie, Wenhe; Liu, Dequan; He, Deyan, E-mail: hedy@lzu.edu.cn

2017-02-28

Silicon is the most promising anode material for the next-generation lithium-ion batteries (LIBs). However, the large volume change during lithiation/delithiation and low intrinsic conductivity hamper its electrochemical performance. Here we report a well-designed LIB anode in which carbon-coated Si nanoparticles/reduced graphene oxide (Si/rGO) multilayer was anchored to nanostructured current collector with stable mechanical support and rapid electron conduction. Furthermore, we improved the integral stability of the electrode through introducing amorphous carbon. The designed anode exhibits superior cyclability, its specific capacity remains above 800 mAh g{sup −1} after 350 cycles at a current density of 2.0 A g{sup −1}. The excellent electrochemical performance can be attributed to the fact that the Si/rGO multilayer is reinforced by the nanostructured current collector and the formed amorphous carbon, which can maintain the structural and electrical integrities of the electrode.

Microstructure and mechanical properties of nanostructure multilayer CrN/Cr coatings on titanium alloy

International Nuclear Information System (INIS)

Wiecinski, Piotr; Smolik, Jerzy; Garbacz, Halina; Kurzydlowski, Krzysztof J.

2011-01-01

Five different nanostructured, multilayer coatings (CrN/Cr)x8 with different thickness ratio of Cr and CrN layers were deposited by PAPVD (Plasma Assisted Physical Vapour Deposition) vacuum arc method on Ti6Al4V titanium alloy. The microstructure, chemical and phase composition of the CrN and Cr sub-layers were characterized by SEM with EDX and Cs-corrected dedicated STEM on cross-sections prepared by focus ion beam. Besides, hardness and Young's modulus of the (Cr/CrN)x8 coatings has been measured. The adhesion has been tested by scratch test method. The obtained (CrN/Cr) multilayer coatings, 5-6 μm in thickness, have homogeneous and nanocrystalline structure, free of pores and cracks. The microstructures of Cr and CrN layers consist of columnar grains below 100 nm in diameter. The hardness and Young's modulus of these coatings depend linearly on thickness ratio of Cr and CrN layers. The decrease of the thickness ratio Cr/CrN 0.81 to 0.15 results in the increase of hardness from 1275 HV to 1710 HV and Young's modulus from 260 GPa to 271 GPa.

Superior critical current density obtained in MgB{sub 2} bulks via employing carbon-coated boron and minor Cu addition

Energy Technology Data Exchange (ETDEWEB)

Peng, Junming; Liu, Yongchang [State Key Laboratory of Hydraulic Engineering Simulation and Safety, School of Materials Science & Engineering, Tianjin University, Tianjin 300072 (China); Ma, Zongqing, E-mail: mzq0320@163.com [State Key Laboratory of Hydraulic Engineering Simulation and Safety, School of Materials Science & Engineering, Tianjin University, Tianjin 300072 (China); Institute for Superconducting and Electronic Materials, AIIM, University of Wollongong, Squires Way, North Wollongong, NSW 2500 (Australia); Shahriar Al Hossain, M. [Institute for Superconducting and Electronic Materials, AIIM, University of Wollongong, Squires Way, North Wollongong, NSW 2500 (Australia); Xin, Ying; Jin, Jianxun [Tianjin University – Futong Group Research Center of Applied Superconductivity, Tianjin University, Tianjin 300072 (China)

2016-09-15

Highlights: • Usage of carbon-coated boron leads to high level of homogeneous carbon doping. • Cu addition improves MgB{sub 2} grain connectivity, leading to higher J{sub c} at low fields. • Cu addition reduces MgO impurity, also contributing to the improvement of J{sub c}. - Abstract: High performance Cu doped MgB{sub 2} bulks were prepared by an in-situ method with carbon-coated amorphous boron as precursor. It was found that the usage of carbon-coated boron in present work leads to the formation of uniformly refined MgB{sub 2} grains, as well as a high level of homogeneous carbon doping in the MgB{sub 2} samples, which significantly enhance the J{sub c} in both Cu doped and undoped bulks compared to MgB{sub 2} bulks with normal amorphous boron precursor. Moreover, minor Cu can service as activator, and thus facilitates the growth of MgB{sub 2} grains and improves crystallinity and grain connectivity, which can bring about the excellent critical current density (J{sub c}) at self fields and low fields (the best values are 7 × 10{sup 5} A/cm{sup 2} at self fields, and 1 × 10{sup 5} A/cm{sup 2} at 2 T, 20 K, respectively). Simultaneously, minor Cu addition can reduce the amount of MgO impurity significantly, also contributing to the improvement of J{sub c} at low fields. Our work suggests that Cu-activated sintering combined with employment of carbon-coated amorphous boron as precursor could be a promising technique to produce practical MgB{sub 2} bulks or wires with excellent J{sub c} on an industrial scale.

HVOF-Sprayed Nano TiO2-HA Coatings Exhibiting Enhanced Biocompatibility

Science.gov (United States)

Lima, R. S.; Dimitrievska, S.; Bureau, M. N.; Marple, B. R.; Petit, A.; Mwale, F.; Antoniou, J.

2010-01-01

Biomedical thermal spray coatings produced via high-velocity oxy-fuel (HVOF) from nanostructured titania (n-TiO2) and 10 wt.% hydroxyapatite (HA) (n-TiO2-10wt.%HA) powders have been engineered as possible future alternatives to HA coatings deposited via air plasma spray (APS). This approach was chosen due to (i) the stability of TiO2 in the human body (i.e., no dissolution) and (ii) bond strength values on Ti-6Al-4V substrates more than two times higher than those of APS HA coatings. To explore the bioperformance of these novel materials and coatings, human mesenchymal stem cells (hMSCs) were cultured from 1 to 21 days on the surface of HVOF-sprayed n-TiO2 and n-TiO2-10 wt.%HA coatings. APS HA coatings and uncoated Ti-6Al-4V substrates were employed as controls. The profiles of the hMSCs were evaluated for (i) cellular proliferation, (ii) biochemical analysis of alkaline phosphatase (ALP) activity, (iii) cytoskeleton organization (fluorescent/confocal microscopy), and (iv) cell/substrate interaction via scanning electron microscopy (SEM). The biochemical analysis indicated that the hMSCs cultured on n-TiO2-10 wt.%HA coatings exhibited superior levels of bioactivity than hMSCs cultured on APS HA and pure n-TiO2 coatings. The cytoskeleton organization demonstrated a higher degree of cellular proliferation on the HVOF-sprayed n-TiO2-10wt.%HA coatings when compared to the control coatings. These results are considered promising for engineering improved performance in the next generation of thermally sprayed biomedical coatings.

Surface spins disorder in uncoated and SiO2 coated maghemite nanoparticles

International Nuclear Information System (INIS)

Zeb, F.; Nadeem, K.; Shah, S. Kamran Ali; Kamran, M.; Gul, I. Hussain; Ali, L.

2017-01-01

We studied the surface spins disorder in uncoated and silica (SiO 2 ) coated maghemite (γ-Fe 2 O 3 ) nanoparticles using temperature and time dependent magnetization. The average crystallite size for SiO 2 coated and uncoated nanoparticles was about 12 and 29 nm, respectively. Scanning electron microscopy (SEM) showed that the nanoparticles are spherical in shape and well separated. Temperature scans of zero field cooled (ZFC)/field cooled (FC) magnetization measurements showed lower average blocking temperature (T B ) for SiO 2 coated maghemite nanoparticles as compared to uncoated nanoparticles. The saturation magnetization (M s ) of SiO 2 coated maghemite nanoparticles was also lower than the uncoated nanoparticles and is attributed to smaller average crystallite size of SiO 2 coated nanoparticles. For saturation magnetization vs. temperature data, Bloch's law (M(T)= M(0).(1− BT b )) was fitted well for both uncoated and SiO 2 coated nanoparticles and yields: B =3×10 −7 K -b , b=2.22 and B=0.0127 K -b , b=0.57 for uncoated and SiO 2 coated nanoparticles, respectively. Higher value of B for SiO 2 coated nanoparticles depicts decrease in exchange coupling due to enhanced surface spins disorder (broken surface bonds) as compared to uncoated nanoparticles. The Bloch's exponent b was decreased for SiO 2 coated nanoparticles which is due to their smaller average crystallite size or finite size effects. Furthermore, a sharp increase of coercivity at low temperatures (<25 K) was observed for SiO 2 coated nanoparticles which is also due to contribution of increased surface anisotropy or frozen surface spins in these smaller nanoparticles. The FC magnetic relaxation data was fitted to stretched exponential law which revealed slower magnetic relaxation for SiO 2 coated nanoparticles. All these measurements revealed smaller average crystallite size and enhanced surface spins disorder in SiO 2 coated nanoparticles than in uncoated γ-Fe 2 O 3 nanoparticles

Synthesis, morphology, optical and photocatalytic performance of nanostructured β-Ga2O3

International Nuclear Information System (INIS)

Girija, K.; Thirumalairajan, S.; Avadhani, G.S.; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.

2013-01-01

Highlights: ► Nanostructures of β-Ga 2 O 3 were prepared using facile reflux condensation process. ► The pH of the reaction mixture shows evident influence on the size and shape of the nanostructures formed. ► The nanostructures exhibited good photocatalytic activity toward Rhodamine B and was found to be superior for higher pH value. - Abstract: Fine powders of β-Ga 2 O 3 nanostructures were prepared via low temperature reflux condensation method by varying the pH value without using any surfactant. The pH value of reaction mixture had great influence on the morphology of final products. High crystalline single phase β-Ga 2 O 3 nanostructures were obtained by thermal treatment at 900 °C which was confirmed by X-ray diffraction and Raman spectroscopy. The morphological analysis revealed rod like nanostructures at lower and higher pH values of 6 and 10, while spindle like structures were obtained at pH = 8. The phase purity and presence of vibrational bands were identified using Fourier transform infrared spectroscopy. The optical absorbance spectrum showed intense absorption features in the UV spectral region. A broad blue emission peak centered at 441 nm due to donor–acceptor gallium–oxygen vacancy pair recombination appeared. The photocatalytic activity toward Rhodamine B under visible light irradiation was higher for nanorods at pH 10

Characterization of nanostructured CuO-porous silicon matrixformed on copper coated silicon substrate via electrochemical etching

International Nuclear Information System (INIS)

Naddaf, M.; Mrad, O.; Al-Zier, A.

2015-01-01

A pulsed anodic etching method has been utilized for nanostructuring of a copper-coated p-type (100) silicon substrate, using HF-based solution as electrolyte. Scanning electron microscopy reveals the formation of a nanostructured matrix that consists of island-like textures with nanosize grains grown onto fiber-like columnar structures separated with etch pits of grooved porous structures. Spatial micro-Raman scattering analysis indicates that the island-like texture is composed of single-phase cupric oxide (CuO) nanocrystals, while the grooved porous structure is barely related to formation of porous silicon (PS). X-ray diffraction shows that both the grown CuO nanostructures and the etched silicon layer have the same preferred (220) orientation. Chemical composition obtained by means of X-ray photoelectron spectroscopic (XPS) analysis confirms the presence of the single-phase CuO on the surface of the patterned CuO-PS matrix. As compared to PS formed on the bare silicon substrate, the room-temperature photoluminescence (PL) from the CuO-PS matrix exhibits an additional weak (blue) PL band as well as a blue shift in the PL band of PS (S-band). This has been revealed from XPS analysis to be associated with the enhancement in the SiO2 content as well as formation of the carbonyl group on the surface in the case of the CuO-PS matrix.(author)

Complex Macrophase-Separated Nanostructure Induced by Microphase Separation in Binary Blends of Lamellar Diblock Copolymer Thin Films

DEFF Research Database (Denmark)

Zhang, Jianqi; Posselt, Dorthe; Smilgies, Detlef-M.

2014-01-01

The nanostructures of thin films spin-coated from binary blends of compositionally symmetric polystyrene-b-polybutadiene (PS-b-PB) diblock copolymer having different molar masses are investigated by means of atomic force microscopy (AFM) and grazing-incidence small-angle X-ray scattering (GISAXS)...

Development of membrane filters with nanostructured porous layer by coating of metal nanoparticles sintered onto a micro-filter

International Nuclear Information System (INIS)

Park, Seok Joo; Park, Young Ok; Lee, Dong Geun; Ryu, Jeong In

2008-01-01

The membrane filter adhered with nanostructured porous layer was made by heat treatment after deposition of nanoparticle-agglomerates sintered in aerosol phase onto a conventional micron-fibrous metal filter as a substrate filter. The Sintered-Nanoparticle-Agglomerates-coated NanoStructured porous layer Membrane Filter (SNA-NSMF), whose the filtration performance was improved compared with the conventional metal membrane filters, was developed by adhesion of nanoparticle-agglomerates of dendrite structure sintered onto the micron-fibrous metal filter. The size of nanoparticle-agglomerates of dendrite structure decreased with increasing the sintering temperature because nanoparticle-agglomerates shrank. When shrinking nanoparticle-agglomerates were deposited and treated with heat onto the conventional micron-fibrous metal filter, pore size of nanostructured porous layer decreased. Therefore, pressure drops of SNA-NSMFs increased from 0.3 to 0.516 KPa and filtration efficiencies remarkably increased from 95.612 to 99.9993%

Study on borate glass system containing with Bi2O3 and BaO for gamma-rays shielding materials: Comparison with PbO

International Nuclear Information System (INIS)

Kaewkhao, J.; Pokaipisit, A.; Limsuwan, P.

2010-01-01

In this work, the mass attenuation coefficients and shielding parameters of borate glass matrices containing with Bi 2 O 3 and BaO have been investigated at 662 keV, and compare with PbO in same glass structure. The theoretical values were calculated by WinXCom software and compare with experiential data. The results found that the mass attenuation coefficients were increased with increasing of Bi 2 O 3 , BaO and PbO concentration, due to increase photoelectric absorption of all glass samples. However, Compton scattering gives dominant contribution to the total mass attenuation coefficients for studied glass samples. Moreover the half value layers (HVL) of glass samples were also better than ordinary concretes and commercial window glass. These results reflecting that the Bi-based glass can use replace Pb in radiation shielding glass. In the case of Ba, may be can use at appropriate energy such as X-rays or lower.

PHASE CONSTITUENTS AND MICROSTRUCTURE OF Ti3Al/Fe3Al + TiN/TiB2 COMPOSITE COATING ON TITANIUM ALLOY

OpenAIRE

JIANING LI; CHUANZHONG CHEN; CUIFANG ZHANG

2011-01-01

Laser cladding of the Fe3Al + B4C/TiN + Al2O3 pre-placed powders on the Ti-6Al-4V alloy can form the Ti3Al/Fe3Al + TiN/TiB2 composite coating, which improved the wear resistance of the Ti-6Al-4V alloy surface. In this study, the Ti3Al/Fe3Al + TiN/TiB2 composite coating has been researched by means of X-ray diffraction and scanning electron microscope. It was found that during the laser cladding process, Al2O3 can react with TiB2, leading to the formations of Ti3Al and B. This principle can be...

Preparation and Oxidation Resistance of Mo-Si-B Coating on Nb-Si Based Alloy Surface

Directory of Open Access Journals (Sweden)

PANG Jie

2018-02-01

Full Text Available Mo-Si-B coating was prepared on Nb-Si alloys to improve the high-temperature oxidation. The influence of the halide activators (NaF and AlF3 on Si-B co-depositing to obtain Mo-Si-B coating on Nb-Si alloys was analyzed by thermochemical calculations. The results show that NaF proves to be more suitable than AlF3 to co-deposit Si and B. Then Mo-Si-B can be coated on Nb-Si based alloys using detonation gun spraying of Mo followed by Si and B co-deposition. The fabricated coatings consist of outer MoSi2 layer with fine boride phase and inner unreacted Mo layer. The mass gain of the Mo-Si-B coating is 1.52mg/cm2 after oxidation at 1250℃ for 100h. The good oxidation resistance results in a protective borosilicate scale formed on the coating.

Precursor-controlled synthesis of hierarchical ZnO nanostructures, using oligoaniline-coated Au nanoparticle seeds

Science.gov (United States)

Krishnan, Deepti; Pradeep, T.

2009-07-01

Shape-selected synthesis of a large number of zinc oxide (ZnO) nano- and microstructures was achieved by the seed-mediated growth of oligoaniline-coated gold nanoparticle precursors. Distinctive ZnO structures such as nanoplates, nanospheres, microstars, microflowers, microthorns and micromultipods were synthesized by this method. Slightly different shapes were obtained in the absence of the seed solution. This is a fast, low temperature (60 °C) and biomimetic route to make a wide variety of structures. The structure and morphology of the nanostructures were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were utilized for the characterization of the nanostructures. A growth mechanism for these nanostructures was proposed based on these results. The concentrations of the reacting species were the main parameter causing the changes in the morphologies. The variation in morphologies of these structures is believed to be due to the ability of the seed solution as well as polyvinylpyrrolidone (PVP) to selectively suppress/depress the growth of certain planes, allowing growth to occur only in certain specific directions. Changes in the amount of growth nuclei with varying sodium hydroxide (NaOH) concentration is also seen to affect the morphology of these structures.

Decreased Fibroblast and Increased Osteoblast Functions on Ionic Plasma Deposited Nanostructured Ti Coatings

Directory of Open Access Journals (Sweden)

Storey Dan

2007-01-01

Full Text Available AbstractBioactive coatings are in high demand to control cellular functions for numerous medical devices. The objective of this in vitro study was to characterize for the first time fibroblast (fibrous scar tissue forming cells adhesion and proliferation on an important polymeric biomaterial (silicone coated with titanium using a novel ionic plasma deposition (IPD process. Fibroblasts are one of the first anchorage-dependent cells to arrive at an implant surface during the wound healing process. Persistent excessive functions of fibroblasts have been linked to detrimental fibrous tissue formation which may cause implant failure. The IPD process creates a surface-engineered nanostructure (with features usually below 100 nm by first using a vacuum to remove all contaminants, then guiding charged metallic ions or plasma to the surface of a medical device at ambient temperature. Results demonstrated that compared to currently used titanium and uncoated silicone, silicone coated with titanium using IPD significantly decreased fibroblast adhesion and proliferation. Results also showed competitively increased osteoblast (bone-forming cells over fibroblast adhesion on silicone coated with titanium; in contrast, osteoblast adhesion was not competitively increased over fibroblast adhesion on uncoated silicone or titanium controls. In this manner, this study strongly suggests that IPD should be further studied for biomaterial applications in which fibrous tissue encapsulation is undesirable (such as for orthopedic implants, cardiovascular components, etc..

In vivo evaluation of CaO-SiO2-P2O5-B2O3 glass-ceramics coating on Steinman pins.

Science.gov (United States)

Lee, Jae Hyup; Hong, Kug Sun; Baek, Hae-Ri; Seo, Jun-Hyuk; Lee, Kyung Mee; Ryu, Hyun-Seung; Lee, Hyun-Kyung

2013-07-01

Surface coating using ceramics improves the bone bonding strength of an implant. We questioned whether a new type of glass-ceramics (BGS-7) coating (CaO-SiO2 -P2 O5 -B2 O3 ) would improve the osseointegration of Steinman pins (S-pins) both biomechanically and histomorphometrically. An in vivo study was performed using rabbits by inserting three S-pins into each iliac bone. The pins were 2.2-mm S-pins with a coating of 30-μm-thick BGS-7 and 550-nm-thick hydroxyapatite (HA), as opposed to an S-pin without coating. A tensile strength test and histomorphometrical evaluation was performed. In the 2-week group, the BGS-7 implant showed a significantly higher tensile strength than the S-pin. In the 4- and 8-week groups, the BGS-7 implants had significantly higher tensile strengths than the S-pins and HA implants. The histomorphometrical study revealed that the BGS-7 implant had a significantly higher contact ratio than the S-pin and HA implants in the 4-week group. The biomechanical and histomorphometrical tests showed that the BGS-7 coating had superior bone bonding properties than the groups without the coating from the initial stage of insertion. The BGS-7 coating of an S-pin will enhance the bone bonding strength, and there might also be an advantage in human bone bonding. © 2013, Copyright the Authors. Artificial Organs © 2013, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Simulation of a silicon neutron detector coated with TiB2 absorber

International Nuclear Information System (INIS)

Krapohl, D; Nilsson, H-E; Petersson, S; Slavicek, T; Thungström, G; Pospisil, S

2012-01-01

Neutron radiation cannot be directly detected in semiconductor detectors and therefore needs converter layers. Planar clean-room processing can be used in the manufacturing process of semiconductor detectors with metal layers to produce a cost-effective device. We used the Geant4 Monte-Carlo toolkit to simulate the performance of a semiconductor neutron detector. A silicon photo-diode was coated with vapour deposited titanium, aluminium thin films and a titaniumdiboride (TiB 2 ) neutron absorber layer. The neutron capture reaction 10B(n, alpha)7Li is taken advantage of to create charged particles that can be counted. Boron-10 has a natural abundance of about SI 19.8%. The emitted alpha particles are absorbed in the underlying silicon detector. We varied the thickness of the converter layer and ran the simulation with a thermal neutron source in order to find the best efficiency of the TiB 2 converter layer and optimize the clean room process.

Oxidation protection of multilayer CVD SiC/B/SiC coatings for 3D C/SiC composite

International Nuclear Information System (INIS)

Liu Yongsheng; Cheng Laifei; Zhang Litong; Wu Shoujun; Li Duo; Xu Yongdong

2007-01-01

A CVD boron coating was introduced between two CVD SiC coating layers. EDS and XRD results showed that the CVD B coating was a boron crystal without other impurity elements. SEM results indicated that the CVD B coating was a flake-like or column-like crystal with a compact cross-section. The crack width in the CVD SiC coating deposited on CVD B is smaller than that in a CVD SiC coating deposited on CVD SiC coating. After oxidation at 700 deg. C and 1000 deg. C, XRD results indicated that the coating was covered by product B 2 O 3 or B 2 O 3 .xSiO 2 film. The cracks were sealed as observed by SEM. There was a large amount of flake-like material on hybrid coating surface after oxidation at 1300 deg. C. Oxidation weight loss and residual flexural strength results showed that hybrid SiC/B/SiC multilayer coating provided better oxidation protection for C/SiC composite than a three layer CVD SiC coating at temperatures from 700 deg. C to 1000 deg. C for 600 min, but worse oxidation protection above 1000 deg. C due to the large amount of volatilization of B 2 O 3 or B 2 O 3 .xSiO 2

Analysis of local regions near the interfaces in nanostructured multicomponent cathodic – arc – vapor – deposition (CAVD) coatings (Ti-Zr-Hf-V-Nb)N

International Nuclear Information System (INIS)

Kraus-Rekhberg, R.; Pogrebnyak, A. D.; Borisyuk, V. N.; Kaverin, M. V.; Belokur, M.A.; Ponomarev, G.; Ojoshi, K.; Takeda, J.; Beresnev, V. M.; Sobol', O. V.

2013-01-01

Multicomponent, nanostructure (Ti- Zr-Hf-V-Nb)N coatings derived using cathodic – Arc – Vapor – Deposition method, were characterized by applying SPB, (μ-PIXE), EDS and SEM-analysis), XRD methods, including ''a-sin 2 φ'' procedure. It was found that through the creation of high elastic strains of compression in coating it is possible to a significant extent enhance its oxidation resistance under high-temperature annealing. During the characterization of coatings the elements and defects’ redistribution was discovered, its segregation through thermally-stimulated diffusion and the spinoidal segregation process end, in the neighborhood of the interfaces, around grains and subgrains, without substantial change of the average nanograin dimension. (authors)

Surface Characterization and Electrocatalytic Properties of the Ti/Ir0.3Ti(0.7-xPbx O2-Coated Electrodes for Oxygen Evolution Reaction in Acidic Media

Directory of Open Access Journals (Sweden)

Oliveira-Sousa Adriana de

2002-01-01

Full Text Available In this work a systematic investigation was carried out of the surface characterization and electrocatalytic activity of Ti/Ir0.3Ti(0.7-xPb x O2-coated electrodes (0 <= x <= 0.7, using the oxygen evolution reaction (OER in 0.5 mol dm-3 H2SO4 as model. The electrodes were prepared by thermal decomposition of IrCl3, TiCl3 and Pb(NO32 at 600 °C for 1 h using Ti as support. X-ray diffraction shows that the layers are crystalline and that the corresponding metal oxides are present. The surface morphology of the samples, before and after use under extensive oxygen evolution (Tafel experiment, was characterized by Scanning Electron Microscopy and the micrograph analyses show that the OER promotes the dissolution of the oxide layer. The redox processes occurring on the surface were characterized by cyclic voltammetry at 20 mV s-1 in 0.5 mol dm-3 aqueous H2SO4, at room temperature, and were controlled by the Ir3+/Ir4+ couple. The measured anodic voltammetric charge is related to the active area of the electrode showing that the replacement of TiO2 by PbO2 increases the surface area with the higher value being at 50 mol% PbO2. After oxygen evolution, the surface area increases slightly. Tafel slopes are independent of Pb content with the values around 60 mV decade-1, which suggest that only Ir sites are active for OER. The values of normalized current (i/q a show some inhibition of the OER as TiO2 is replaced by PbO2 suggesting that PbO2, can be a good choice, with potential to improve the selectivity of the system. The reaction order with respect to H+ ion is zero at constant overpotential and ionic strength. The values of Tafel slope and reaction order indicate that a single reaction mechanism is operating.

Using the particle beam optics lab. (PBO LABtm) for beamline design and analysis

International Nuclear Information System (INIS)

Gillespie, G.H.; Hill, B.W.; Martono, H.; Moore, J.M.; Lampel, M.C.; Brown, N.A.

1999-01-01

The Particle Beam Optics Interactive Computer Laboratory (PBO Lab) represents a new approach to providing software for particle beam optics modeling. The PBO Lab includes four key elements: a graphic user interface shell; a graphic beamline construction kit for users to interactively and visually construct optical beam lines; a knowledge database on the physics and technology of optical elements, and various charged particle optics computational engines. A first-order matrix code, including a space charge model, can be used to produce scaled images of beamlines together with overlays of single trajectories and beam envelopes. The qualitative results of graphically sliding beamline components, or adjusting bend angles, can be explored interactively. Quantitative computational engines currently include the third-order TRANSPORT code and the multi-particle ray tracing program TURTLE. The use of the PBO Lab for designing and analyzing a second order achromatic bend is illustrated with the Windows 95/NT version of the software. (authors)

SaOS-2 cell response to macro-porous boron-incorporated TiO{sub 2} coating prepared by micro-arc oxidation on titanium

Energy Technology Data Exchange (ETDEWEB)

Huang, Qianli [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Elkhooly, Tarek A. [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Department of Ceramics, Inorganic Chemical Industries Division, National Research Centre, Dokki, 12622 Cairo (Egypt); Liu, Xujie [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Zhang, Ranran; Yang, Xing; Shen, Zhijian [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Feng, Qingling, E-mail: biomater@mail.tsinghua.edu.cn [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory of Advanced Materials of Ministry of Education of China, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

2016-10-01

The aims of the present study were to develop boron-incorporated TiO{sub 2} coating (B-TiO{sub 2} coating) through micro-arc oxidation (MAO) and subsequently evaluate the effect of boron incorporation on the in vitro biological performance of the coatings. The physicochemical properties of B-TiO{sub 2} coating and its response to osteoblast like cells (SaOS-2) were investigated compared to the control group without boron (TiO{sub 2} coating). The morphological and X-ray diffraction results showed that both coatings exhibited similar surface topography and phase composition, respectively. However, the incorporation of B led to an enhancement in the surface hydrophilicity of B-TiO{sub 2} coating. The spreading of SaOS-2 cells on B-TiO{sub 2} coating was faster than that on TiO{sub 2} coating. The proliferation rate of SaOS-2 cells cultured on B-TiO{sub 2} decreased after 5 days of culture compared to that on TiO{sub 2} coating. SaOS-2 cells cultured on B-TiO{sub 2} coating exhibited an enhanced alkaline phosphatase (ALP) activity, Collagen I synthesis and in vitro mineralization compared to those on TiO{sub 2} coating. The present findings suggest that B-TiO{sub 2} coating is a promising candidate surface for orthopedic implants. - Highlights: • SaOS-2 cell response to pure TiO{sub 2} and B-TiO{sub 2} coatings was investigated. • Initial cell spreading on B-TiO{sub 2} coating was accelerated compared to that on TiO{sub 2} coating. • Cell proliferation on B-TiO{sub 2} coating was inhibited compared to that on TiO{sub 2} coating. • Cell differentiation on B-TiO{sub 2} coating was enhanced compared to that on TiO{sub 2} coating.

(SiC/AlN)2 multilayer film as an effective protective coating for sintered NdFeB by magnetron sputtering

Science.gov (United States)

You, Yu; Li, Heqin; Huang, Yiqin; Tang, Qiong; Zhang, Jing; Xu, Jun

2017-08-01

SiC/AlN and (SiC/AlN)2 multilayer films with a well-arranged bilayer structure and a four-layer structure are prepared respectively on NdFeB substrates by a magnetron sputtering method. Crystal phase and microstructures of the SiC/AlN and (SiC/AlN)2 films are investigated using x-ray diffraction (XRD), field-emission scanning electron microscope (FESEM) and atomic force microscope (AFM). It is observed that the surface of the (SiC/AlN)2 four-layer film is much denser and smoother than that of the SiC/AlN bilayer film. Corrosion behaviors of the NdFeB substrates coated with SiC/AlN and (SiC/AlN)2 films as well as the bare NdFeB substrate are evaluated by potentiodynamic polarization curve tests. It is revealed that the lateral growth structures developed in interfaces are favorable for an enhanced corrosion resistance. Corrosion current densities of the (SiC/AlN)2 coated NdFeB measured in acid, alkali and salt solutions are 2.796  ×  10-9, 3.65  ×  10-6, and 2.912  ×  10-6 A cm-2, respectively, which are much lower than those of the bare NdFeB and the SiC/AlN coated NdFeB.

Characterization of nanostructured CuO-porous silicon matrix formed on copper-coated silicon substrate via electrochemical etching

Science.gov (United States)

Naddaf, M.; Mrad, O.; Al-zier, A.

2014-06-01

A pulsed anodic etching method has been utilized for nanostructuring of a copper-coated p-type (100) silicon substrate, using HF-based solution as electrolyte. Scanning electron microscopy reveals the formation of a nanostructured matrix that consists of island-like textures with nanosize grains grown onto fiber-like columnar structures separated with etch pits of grooved porous structures. Spatial micro-Raman scattering analysis indicates that the island-like texture is composed of single-phase cupric oxide (CuO) nanocrystals, while the grooved porous structure is barely related to formation of porous silicon (PS). X-ray diffraction shows that both the grown CuO nanostructures and the etched silicon layer have the same preferred (220) orientation. Chemical composition obtained by means of X-ray photoelectron spectroscopic (XPS) analysis confirms the presence of the single-phase CuO on the surface of the patterned CuO-PS matrix. As compared to PS formed on the bare silicon substrate, the room-temperature photoluminescence (PL) from the CuO-PS matrix exhibits an additional weak `blue' PL band as well as a blue shift in the PL band of PS (S-band). This has been revealed from XPS analysis to be associated with the enhancement in the SiO2 content as well as formation of the carbonyl group on the surface in the case of the CuO-PS matrix.

Nanostructures and surface hydrophobicity of self-assembled thermosets involving epoxy resin and poly(2,2,2-trifluoroethyl acrylate)-block-poly(ethylene oxide) amphiphilic diblock copolymer.

Science.gov (United States)

Yi, Fangping; Zheng, Sixun; Liu, Tianxi

2009-02-19

Poly(2,2,2-trifluoroethyl acrylate)-block-poly(ethylene oxide) (PTFEA-b-PEO) amphiphilic diblock copolymer was synthesized via the reversible addition-fragmentation transfer polymerization of 2,2,2-triffluroethyl acrylate with dithiobenzoyl-terminated poly(ethylene oxide) as a chain-transfer agent. The amphiphilic diblock copolymer was incorporated into epoxy resin to prepare the nanostructured epoxy thermosets. The nanostructures were investigated by means of atomic force microscopy, small-angle X-ray scattering, and dynamic mechanical analysis. In terms of the miscibility of the subchains of the block copolymer with epoxy after and before curing reaction, it is judged that the formation of the nanostructures follows the mechanism of self-assembly. The static contact angle measurements indicate that the nanostructured thermosets containing PTFEA-b-PEO diblock copolymer displayed a significant enhancement in surface hydrophobicity as well as a reduction in surface free energy. The improvement in surface properties was ascribed to the enrichment of the fluorine-containing subchain (i.e., PTFEA block) of the amphiphilic diblock copolymer on the surface of the nanostructured thermosets, which was evidenced by surface atomic force microscopy and energy-dispersive X-ray spectroscopy.

Direct Observation on Spin-Coating Process of PS- b -P2VP Thin Films

Energy Technology Data Exchange (ETDEWEB)

Ogawa, Hiroki; Takenaka, Mikihito; Miyazaki, Tsukasa; Fujiwara, Akihiko; Lee, Byeongdu; Shimokita, Keisuke; Nishibori, Eiji; Takata, Masaki

2016-05-10

We studied the structural development of symmetric poly(styrene-b-2-vinylpyridine) (PS-b-P2VP) block copolymers during spin-coating using in situ grazing incidence small angle X-ray scattering (GISAXS) measurements. During the spin-coating process, after the formation of the micelles in dilute solution, the selective solvent induced two kinds of the morphological transition. Firstly, the disordered spherical micelles were transformed into a BCC lattice of spheres of which the (110) plane was oriented perpendicularly to the substrate surface. Secondly, further evaporation induced a transition from spheres on the BCC lattice into cylindrical structures. The orientation of the cylinders perpendicular to the substrate surface was induced by solvent convection perpendicular to the substrate, which occurs during rapid solvent evaporation. After this transition, vitrification of PS and P2VP prevented any further transition from cylinders to the more thermodynamically stable lamellar structures, as are generally observed as the bulk equilibrium state.

Microstructure and wear properties of laser cladding Ti-Al-Fe-B coatings on AA2024 aluminum alloy

International Nuclear Information System (INIS)

Xu Jiang; Liu Wenjin; Kan Yide; Zhong Minlin

2006-01-01

In order to improve wear resistance of aluminum alloy, the in situ synthesized TiB 2 and Ti 3 B 4 peritectic composite particulate reinforced metal matrix composite formed on the 2024 aluminum alloy by laser cladding with a powder mixture of Fe coated Boron, Ti and Al was successfully achieved using 3 kW CW CO 2 laser. The laser cladding coating present excellent bonding with aluminum alloy substrate. The chemical composition, microstructure and phase structure of the composite clad coating were analyzed by energy dispersive X-ray spectroscopy (EDX), SEM and XRD. The typical microstructure of composite coating is composed of TiB 2 , Ti 3 B 4 , Al 3 Ti, Al 3 Fe and α-Al. The surface hardness of cladding coating is increased with the amount of added Fe coated B and Ti powder which determines the amount of TiB 2 and Ti 3 B 4 peritectic composite particulate, and obviously higher than that of substrate. The wear tests were carried out using a FALEX-6 type pin-on-disc machine. The test results show that the composite coatings with the in situ synthesized TiB 2 and Ti 3 B 4 peritectic improve wear resistance when compared with the as-received Al substrate

Preparation of porous lead from shape-controlled PbO bulk by in situ electrochemical reduction in ChCl-EG deep eutectic solvent

Science.gov (United States)

Ru, Juanjian; Hua, Yixin; Xu, Cunying; Li, Jian; Li, Yan; Wang, Ding; Zhou, Zhongren; Gong, Kai

2015-12-01

Porous lead with different shapes was firstly prepared from controlled geometries of solid PbO bulk by in situ electrochemical reduction in choline chloride-ethylene glycol deep eutectic solvents at cell voltage 2.5 V and 353 K. The electrochemical behavior of PbO powders on cavity microelectrode was investigated by cyclic voltammetry. It is indicated that solid PbO can be directly reduced to metal in the solvent and a nucleation loop is apparent. Constant voltage electrolysis demonstrates that PbO pellet can be completely converted to metal for 13 h, and the current efficiency and specific energy consumption are about 87.79% and 736.82 kWh t-1, respectively. With the electro-deoxidation progress on the pellet surface, the reduction rate reaches the fastest and decreases along the distance from surface to inner center. The morphologies of metallic products are porous and mainly consisted of uniform particles which connect with each other by finer strip-shaped grains to remain the geometry and macro size constant perfectly. In addition, an empirical model of the electro-deoxidation process from spherical PbO bulk to porous lead is also proposed. These findings provide a novel and simple route for the preparation of porous metals from oxide precursors in deep eutectic solvents at room temperature.

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

Science.gov (United States)

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

Peculiar features of metallurgical processes at plasma-arc spraying of coatings, made of steel wire with powder fillers B4C and B4C+ZrO2

Directory of Open Access Journals (Sweden)

Георгій Михайлович Григоренко

2016-11-01

Full Text Available The interaction of metallurgical processes occurring in plasma-arc spraying between the steel shell and the carbide fillers of B4C and B4C cored wires with the addition of nanocrystalline ZrO2 powder has been analyzed. Iron-boron compounds alloyed with carbon are formed in ingots as a result of ferritiс coating of wire interacrion with fillers while the ferritic matrix contains boride and carboboride eutectics. Average microhardness of the carboboride compounds and the matrix is high – 17,78; 16,40 and 8,69; 9,95 GPa for the ingots with с B4C and B4C+ZrO2 respectively. The best quality coatings with low porosity (~1%, lamellar structure consisting of ferrite matrix reinforced with dispersed Fe borides, were obtained at a higher heat input (plasmatron current 240-250 A. The average amount of oxides in the coatings makes 15%. 0,5% addition of nanopowder ZrO2 accelerates dispersed iron-boron compounds forming, promotes their uniform distribution in the structure and improves coating microhardness up to 7,0 GPa. Application of the differential thermal analysis method to simulate the interaction processes between the steel shell and the filler during the heating of wire in the shielding gas makes it possible to promote formation of new phases (borides and carboborides of iron and to predict the phase composition of the coatings

A high-sensitive ultraviolet photodetector composed of double-layered TiO{sub 2} nanostructure and Au nanoparticles film based on Schottky junction

Energy Technology Data Exchange (ETDEWEB)

Wang, Huan; Qin, Pei [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006 (China); Yi, Guobin, E-mail: ygb702@163.com [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006 (China); Zu, Xihong [School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006 (China); Zhang, Li, E-mail: zhangli2368@126.com [School of Materials and Energy, Guangdong University of Technology, Guangzhou, 510006 (China); Hong, Wei; Chen, Xudong [School of Chemistry and Chemical Engineering, Sun Yat-Sen (Zhongshan) University, Guangzhou, 510275 (China)

2017-06-15

In this study, a Schottky-type ultraviolet (UV) photodetector based on double-layered nanostructured TiO{sub 2}/Au films was fabricated. Double-layered titanium dioxide (TiO{sub 2}) nanostructures composed of one layer of TiO{sub 2} nano-flowers on one layer of TiO{sub 2} nanorods on fluorine-doped tin oxide (FTO) pre-coated glass substrates were synthesized via a convenient hydrothermal method using titanium butoxide and hydrochloric acid as the starting precursor, without involving the use of any other surfactants and catalysts. A granular-shaped thin-layer of Au film using vacuum sputter coating technique was subsequently deposited on TiO{sub 2} for the formation of Schottky-type photodetector. The as-fabricated Schottky device showed various photocurrent responses when irradiated with different wavelength of UV light. This suggests that the newly-developed photodetectors have promising potential for identifying different UV light wavelengths. - Highlights: • A novel double-layered TiO{sub 2} nanostructure was synthesized by a simple method. • An UV photodetector composed of TiO{sub 2} and Au was designed and fabricated. • The preparation method of TiO{sub 2}/Au UV photodetector was simple and convenient. • The UV photodetector based on TiO{sub 2}/Au showed excellent sensitivity to UV light.

Electrodeposition of nanostructured Sn-Zn coatings

Science.gov (United States)

Salhi, Y.; Cherrouf, S.; Cherkaoui, M.; Abdelouahdi, K.

2016-03-01

The electrodeposition of Sn-Zn coating at ambient temperature was investigated. The bath consists of metal salts SnCl2·2H2O and ZnSO4·7H2O and sodium citrate (NaC6H5Na3O7·2H2O) as complexing agent. To prevent precipitation, the pH is fixed at 5. Reducing tin and zinc through Sncit2- and ZnHcit- complex respectively is confirmed by the presence of two cathodic peaks on the voltammogram. The kinetic of tin (II) reduction process is limited by the SnCit2- dissociation. The SEM and TEM observations have showed that the coating consists of a uniform Sn-Zn layer composed of fine grains on which tin aggregates grow up. XRD revealed peaks corresponding to the hexagonal Zn phase and the tetragonal β-Sn phase.

Spontaneous Evolution of Nanostructure in Composite Films Consisting of Mixtures of Two Different Block Copolymer Micelles

Science.gov (United States)

Kim, Sehee; Char, Kookheon; Sohn, Byeong-Hyeok

2010-03-01

Diblock copolymers consisting of two immiscible polymer blocks covalently bonded together form various self-assembled nanostructures such as spheres, cylinders, and lamellae in bulk phase. In a selective solvent, however, they assemble into micelles with soluble corona brushes and immiscible cores. Both polystyrene-poly(4-vinylpyridine) (PS-b-P4VP) and polystyrene-poly(2-vinylpyridine) (PS-b-P2VP) diblock copolymers form micelles with PS coronas and P4VP or P2VP cores in a PS selective solvent (toluene). By varying the mixture ratio between PS-b-P4VP and PS-b-P2VP, composite films based on the micellar mixtures of PS-b-P4VP and PS-b-P2VP were obtained by spin-coating, followed by the solvent annealing with tetrahydrofuran (THF) vapor. Since THF is a solvent for both PS and P2VP blocks and, at the same time, a non-solvent for the P4VP block, PS-P2VP micelles transformed to lamellar multilayers while PS-P4VP micelles remained intact during the THF annealing. The spontaneous evolution of nanostructure in composite films consisting of lamellae layers with BCP micelles were investigated in detail by cross-sectional TEM and AFM.

Surface spins disorder in uncoated and SiO{sub 2} coated maghemite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zeb, F. [Nanoscience and Technology Laboratory, International Islamic University, H-10, 44000 Islamabad (Pakistan); Nadeem, K., E-mail: kashif.nadeem@iiu.edu.pk [Nanoscience and Technology Laboratory, International Islamic University, H-10, 44000 Islamabad (Pakistan); Shah, S. Kamran Ali; Kamran, M. [Nanoscience and Technology Laboratory, International Islamic University, H-10, 44000 Islamabad (Pakistan); Gul, I. Hussain [School of Chemical & Materials Engineering, National University of Sciences and Technology (NUST), H-12, 44000 Islamabad, Pakistan (Pakistan); Ali, L. [Materials Research Laboratory, International Islamic University, H-10, 44000 Islamabad (Pakistan)

2017-05-01

We studied the surface spins disorder in uncoated and silica (SiO{sub 2}) coated maghemite (γ-Fe{sub 2}O{sub 3}) nanoparticles using temperature and time dependent magnetization. The average crystallite size for SiO{sub 2} coated and uncoated nanoparticles was about 12 and 29 nm, respectively. Scanning electron microscopy (SEM) showed that the nanoparticles are spherical in shape and well separated. Temperature scans of zero field cooled (ZFC)/field cooled (FC) magnetization measurements showed lower average blocking temperature (T{sub B}) for SiO{sub 2} coated maghemite nanoparticles as compared to uncoated nanoparticles. The saturation magnetization (M{sub s}) of SiO{sub 2} coated maghemite nanoparticles was also lower than the uncoated nanoparticles and is attributed to smaller average crystallite size of SiO{sub 2} coated nanoparticles. For saturation magnetization vs. temperature data, Bloch's law (M(T)= M(0).(1− BT{sup b})) was fitted well for both uncoated and SiO{sub 2} coated nanoparticles and yields: B =3×10{sup −7} K{sup -b}, b=2.22 and B=0.0127 K{sup -b}, b=0.57 for uncoated and SiO{sub 2} coated nanoparticles, respectively. Higher value of B for SiO{sub 2} coated nanoparticles depicts decrease in exchange coupling due to enhanced surface spins disorder (broken surface bonds) as compared to uncoated nanoparticles. The Bloch's exponent b was decreased for SiO{sub 2} coated nanoparticles which is due to their smaller average crystallite size or finite size effects. Furthermore, a sharp increase of coercivity at low temperatures (<25 K) was observed for SiO{sub 2} coated nanoparticles which is also due to contribution of increased surface anisotropy or frozen surface spins in these smaller nanoparticles. The FC magnetic relaxation data was fitted to stretched exponential law which revealed slower magnetic relaxation for SiO{sub 2} coated nanoparticles. All these measurements revealed smaller average crystallite size and enhanced surface

Synthesis, surface group modification of 3D MnV{sub 2}O{sub 6} nanostructures and adsorption effect on Rhodamine B

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wanqun, E-mail: wqz@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at Micro-scale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Chemical Experimental Teaching Center, University of Science and Technology of China, Hefei, Anhui 230026 (China); Shi, Lei, E-mail: shil@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at Micro-scale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Tang, Kaibin; Liu, Zhongping [Hefei National Laboratory for Physical Sciences at Micro-scale, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2012-07-15

Highlights: ► Fabrication of urchin-like MnV{sub 2}O{sub 6} with oxygen-containing surface groups. ► Mn{sub 0.5}V{sub 2}O{sub 5}·nH{sub 2}O as an intermediate product holds the key to the final products. ► 3D architectures of MnV{sub 2}O{sub 6} with oxygen-containing surface groups as sorbent. ► The sorbent shows a good adsorption ability. -- Abstract: Highly uniform 3D MnV{sub 2}O{sub 6} nanostructures modified by oxygen functional groups (-COO-) were successfully prepared in large quantities by an approach involving preparation of vanadyl ethylene glycolate as the precursor. The growth and self-assembly of MnV{sub 2}O{sub 6} nanobelts and nanorods could be readily tuned by additive species and quantities, which brought different morphologies and sizes to the final products. With a focus on the regulation of structure, the formation process of 3D architectures of MnV{sub 2}O{sub 6} by self-assembly of nanobelts was followed by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The consecutive processes of vanadyl ethylene glycolate and benzoyl peroxide assisted formation of layered structure Mn{sub 0.5}V{sub 2}O{sub 5}·nH{sub 2}O, growth of aligned MnV{sub 2}O{sub 6} nanobelts, and oriented assembly were proposed for the growth mechanism. The band gap vs. different morphology was also studied. Optical characterization of these MnV{sub 2}O{sub 6} with different morphologies showed direct bandgap energies at 1.8–1.95 eV. The adsorption properties of 3D MnV{sub 2}O{sub 6} nanostructures synthesized under different conditions were investigated through the removal test of Rhodamine B in aqueous water, and the 3D nanostructures synthesized with 30 g L{sup −1} benzoyl peroxide showed good adsorption capability of Rhodamine B.

Antimicrobial activity of novel nanostructured Cu-SiO2 coatings prepared by chemical vapour deposition against hospital related pathogens.

Science.gov (United States)

Varghese, Sajnu; Elfakhri, Souad O; Sheel, David W; Sheel, Paul; Bolton, Frederick J Eric; Foster, Howard A

2013-09-05

There is increasing recognition that the healthcare environment acts as an important reservoir for transmission of healthcare acquired infections (HCAI). One method of reducing environmental contamination would be use of antimicrobial materials. The antimicrobial activity of thin silica-copper films prepared by chemical vapour deposition was evaluated against standard strains of bacteria used for disinfectant testing and bacteria of current interest in HCAI. The structure of the coatings was determined using Scanning Electron Microscopy and their hardness and adhesion to the substrate determined. Antimicrobial activity was tested using a method based on BS ISO 22196:2007. The coatings had a pale green-brown colour and had a similar hardness to steel. SEM showed nano-structured aggregates of Cu within a silica matrix. A log10 reduction in viability of >5 could be obtained within 4 h for the disinfectant test strains and within 6 h for producing Acinetobacter baumannii, Klebsiella pneumoniae and Stenotrophomonas maltophilia. Activity against the other hospital isolates was slower but still gave log10 reduction factors of >5 for extended spectrum β-lactamase producing Escherichia coli and >3 for vancomycin resistant Enterococcus faecium, methicillin resistant Staphylococcus aureus and Pseudomonas aeruginosa within 24 h. The results demonstrate the importance of testing antimicrobial materials destined for healthcare use against isolates of current interest in hospitals as well as standard test strains. The coatings used here can also be applied to substrates such as metals and ceramics and have potential applications where reduction of microbial environmental contamination is desirable.

Microstructure Analysis of Laser Remelting for Thermal Barrier Coatings on the Surface of Titanium Alloy

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Lu Bin

2016-01-01

Full Text Available In this paper, the preparation and organization performance of thermal barrier coatings (TCBs on the surface of titanium were studied experimentally. Nanostructured 8 wt% yttria partially stabilized zirconia coatings were deposited by air plasma spraying. The microstructure of nanostructured and the conventional coating was studied after laser remelting. It has shown that formed a network of micro-cracks and pits after laser remelting on nanostructured coatings. With the decrease of the laser scanning speed, mesh distribution of micro cracks was gradually thinning on nanostructured coatings. Compared with conventional ceramic layers, the mesh cracks of nanostructured coating is dense and the crack width is small.

Surface analysis and biocorrosion properties of nanostructured surface sol-gel coatings on Ti6Al4V titanium alloy implants.

Science.gov (United States)

Advincula, Maria C; Petersen, Don; Rahemtulla, Firoz; Advincula, Rigoberto; Lemons, Jack E

2007-01-01

Surfaces of biocompatible alloys used as implants play a significant role in their osseointegration. Surface sol-gel processing (SSP), a variant of the bulk sol-gel technique, is a relatively new process to prepare bioreactive nanostructured titanium oxide for thin film coatings. The surface topography, roughness, and composition of sol-gel processed Ti6Al4V titanium alloy coatings was investigated by atomic force microscopy (AFM) and X-ray electron spectroscopy (XPS). This was correlated with corrosion properties, adhesive strength, and bioreactivity in simulated body fluids (SBF). Electroimpedance spectroscopy (EIS) and polarization studies indicated similar advantageous corrosion properties between sol-gel coated and uncoated Ti6Al4V, which was attributed to the stable TiO2 composition, topography, and adhesive strength of the sol-gel coating. In addition, inductive coupled plasma (ICP) and scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) analysis of substrates immersed in SBF revealed higher deposition of calcium and phosphate and low release rates of alloying elements from the sol-gel modified alloys. The equivalent corrosion behavior and the definite increase in nucleation of calcium apatite indicate the potential of the sol-gel coating for enhanced bioimplant applications. 2006 Wiley Periodicals, Inc.

Mo-Si-B-Based Coatings for Ceramic Base Substrates

Science.gov (United States)

Perepezko, John Harry (Inventor); Sakidja, Ridwan (Inventor); Ritt, Patrick (Inventor)

2015-01-01

Alumina-containing coatings based on molybdenum (Mo), silicon (Si), and boron (B) ("MoSiB coatings") that form protective, oxidation-resistant scales on ceramic substrate at high temperatures are provided. The protective scales comprise an aluminoborosilicate glass, and may additionally contain molybdenum. Two-stage deposition methods for forming the coatings are also provided.

Covalent functionalization of metal oxide and carbon nanostructures with polyoctasilsesquioxane (POSS) and their incorporation in polymer composites

International Nuclear Information System (INIS)

Gomathi, A.; Gopalakrishnan, K.; Rao, C.N.R.

2010-01-01

Polyoctasilsesquioxane (POSS) has been employed to covalently functionalize nanostructures of TiO 2 , ZnO and Fe 2 O 3 as well as carbon nanotubes, nanodiamond and graphene to enable their dispersion in polar solvents. Covalent functionalization of these nanostructures with POSS has been established by electron microscopy, EDAX analysis and infrared spectroscopy. On heating the POSS-functionalized nanostructures, silica-coated nanostructures are obtained. POSS-functionalized nanoparticles of TiO 2 , Fe 2 O 3 and graphite were utilized to prepare polymer-nanostructure composites based on PVA and nylon-6,6.

Microstructure and wear properties of laser cladding Ti-Al-Fe-B coatings on AA2024 aluminum alloy

Energy Technology Data Exchange (ETDEWEB)

Xu Jiang [Laser Processing Research Center, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China)]. E-mail: xujiang73@sina.com.cn; Liu Wenjin [Laser Processing Research Center, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China); Kan Yide [Laser Processing Research Center, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China); Zhong Minlin [Laser Processing Research Center, Mechanical Engineering Department, Tsinghua University, Beijing 10084 (China)

2006-07-01

In order to improve wear resistance of aluminum alloy, the in situ synthesized TiB{sub 2} and Ti{sub 3}B{sub 4} peritectic composite particulate reinforced metal matrix composite formed on the 2024 aluminum alloy by laser cladding with a powder mixture of Fe coated Boron, Ti and Al was successfully achieved using 3 kW CW CO{sub 2} laser. The laser cladding coating present excellent bonding with aluminum alloy substrate. The chemical composition, microstructure and phase structure of the composite clad coating were analyzed by energy dispersive X-ray spectroscopy (EDX), SEM and XRD. The typical microstructure of composite coating is composed of TiB{sub 2}, Ti{sub 3}B{sub 4}, Al{sub 3}Ti, Al{sub 3}Fe and {alpha}-Al. The surface hardness of cladding coating is increased with the amount of added Fe coated B and Ti powder which determines the amount of TiB{sub 2} and Ti{sub 3}B{sub 4} peritectic composite particulate, and obviously higher than that of substrate. The wear tests were carried out using a FALEX-6 type pin-on-disc machine. The test results show that the composite coatings with the in situ synthesized TiB{sub 2} and Ti{sub 3}B{sub 4} peritectic improve wear resistance when compared with the as-received Al substrate.

Synthesis and characterization of a PbO2-clay nanocomposite: Removal of lead from water using montmorillonite

International Nuclear Information System (INIS)

Aroui, L.; Zerroual, L.; Boutahala, M.

2012-01-01

Graphical abstract: The replacement of Na by Pb in the interlayer space of the smectite leads to a decrease in the intensity of the the (0 0 1) reflection as the concentration of lead nitrate increases. A significant restructuring at the particle scale is observed leading probably to the exfoliation of the caly. In addition, the thermal behaviour of the montmorillonite samples with regard to their dehydration and dehydroxilation capacities is significantly influenced. This leads to a lowering of the water content and a decrease in the ionic conductivity of the clay. Highlights: ► In the clay, Pb replaces Na ions and a significant restructuring at the particle scale is observed. ► Pb influenced significantly the thermal behaviour of the clay with regard to its dehydration. ► In the interlayer space, the exchange of Na by Pb leads to a decrease in the protonic conductivity. ► A PbO 2 -clay nanocomposite material with good conductivity is synthesized. -- Abstract: The aim of this paper is to present the results obtained with Pb(II) sorption on an Algerian Clay. The experiments were carried out using a batch process. Powder X-rays diffraction patterns (PXRD) prove that in the montmorillonite Pb replaces Na ions. A significant restructuring at the particle scale is observed leading to the disappearance of the d 001 reflection of the clay at high concentrations of lead. The replacement of hydrated Na with Pb ions influenced significantly the thermal behaviour of the montmorillonite samples with regard to their dehydration and dehydroxilation capacities with a lowering of the water content. A PbO 2 -clay composite material with good electrical conductivity is synthesized.

Nanostructure of plasma-sprayed hydroxyapatite coating

International Nuclear Information System (INIS)

Suvorova, E.I.; Klechkovskaya, V.V.; Bobrovsky, V.V.; Khamchukov, Yu.D.; Klubovich, V.V.

2003-01-01

Calcium phosphate coatings were studied by high-resolution transmission microscopy, microdiffraction, and X-ray energy-dispersive spectroscopy. Coatings were prepared by spraying hydroxyapatite targets onto copper, nickel, and chromium substrates and onto NaCl and BaF 2 single crystals in an argon plasma at a gas pressure of ∼1 Pa; the sputter power was about 200 W; and the RF-generator frequency was 13.56 MHz. Under the conditions used, thin layers of nanocrystalline hydroxyapatite were formed regardless of the nature of the substrate

Effects of B{sub 2}O{sub 3} content and sintering temperature on crystallization and microstructure of CBS glass–ceramic coatings

Energy Technology Data Exchange (ETDEWEB)

Li, Pengyang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Wang, Shubin, E-mail: shubinwang@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials and Engneering, Beihang University, Beijing 100191 (China); Liu, Jianggao; Feng, Mengjie; Yang, Xinwang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

2015-11-30

Graphical abstract: (a) TEM photogram of CG3 sintered at 800 °C, crystals are obvious; (b) the XRD patterns of CG3 glass samples sintered at various temperatures; (c) SEM photogram of CG3 sintered at 800 °C; (d) Kissinger, Augis–Bennett and Ozawa kinetics plots of CG3 glass samples. - Highlights: • Combining sol–gel method with direct sintering method to reduce the temperature of coatings formation. • Characterizing CaO–SiO{sub 2}–B{sub 2}O{sub 3} glass–ceramic coatings on porous substrates. • Surface crystallization of CBS glass–ceramic coatings: nucleation and kinetics. • Activation energies for crystal growth in CBS glass–ceramics with different contents of B{sub 2}O{sub 3}. - Abstract: Borosilicate glass–ceramics precursors with varying compositional ratios in the CaO–SiO{sub 2}–B{sub 2}O{sub 3} (CBS) system were synthesized by sol–gel method. The precursors were calcined at 1200 °C for 2 h to form glass powders. The glass–ceramics were prepared by overlaying glass slurries on the substrates before sintering at different temperatures. The as-prepared glasses and glass–ceramics were characterized by differential scanning calorimetry and X-ray diffraction. The crystallization activation energies (E{sub c}) were calculated using the Kissinger method from DSC results. The morphology and crystallization behavior of the glass–ceramics were monitored by scanning electron microscopy. Both glass transition and crystallization temperatures decreased, however, the metastable zone increased. The E{sub c} values of CBS glasses and glass–ceramics were 254.1, 173.2 and 164.4 kJ/mol with increasing B{sub 2}O{sub 3} content, whereas that of the calcined G3 glass was 104.9 kJ/mol. Finally, the coatings were prepared at a low temperature (700 °C). The crystals that grew on the surface of multilayer coatings demonstrated heterogeneous surface nucleation and crystallization after heat-treatment from 700 °C to 850 °C for 4 h.

Studies of surface morphology and optical properties of ZnO nanostructures grown on different molarities of TiO_2 seed layer

International Nuclear Information System (INIS)

Asib, N. A. M.; Afaah, A. N.; Aadila, A.; Khusaimi, Z.; Rusop, M.

2016-01-01

Titanium dioxide (TiO_2) seed layer was prepared by using sol-gel spin-coating technique, followed by growth of 0.01 M of Zinc oxide (ZnO) nanostructures by solution-immersion. The molarities of TiO_2 seed layer were varied from 1.1 M to 0.100 M on glass substrates. The nanostructures thin films were characterized by Field Emission Scanning Electrons Microscope (FESEM), Photoluminescence (PL) spectroscopy and Ultraviolet-Visible (UV-Vis) spectroscopy. FESEM images demonstrate that needle-like ZnO nanostructures are formed on all TiO_2 seed layer. The smallest diameter of needle-like ZnO nanostructures (90.3 nm) were deposited on TiO_2 seed layer of 0.100 M. PL spectra of the TiO_2: ZnO nanostructures thin films show the blue shifted emissions in the UV regions compared to the ZnO thin film. Meanwhile, UV-vis spectra of films display high absorption in the UV region and high trasparency in the visible region. The highest absorbance at UV region was recorded for sample which has 0.100 M of TiO_2 seed layer.

Synthesis and characterization of noble metal–titania core–shell nanostructures with tunable shell thickness

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Bartosz Bartosewicz

2017-10-01

Full Text Available Core–shell nanostructures have found applications in many fields, including surface enhanced spectroscopy, catalysis and solar cells. Titania-coated noble metal nanoparticles, which combine the surface plasmon resonance properties of the core and the photoactivity of the shell, have great potential for these applications. However, the controllable synthesis of such nanostructures remains a challenge due to the high reactivity of titania precursors. Hence, a simple titania coating method that would allow better control over the shell formation is desired. A sol–gel based titania coating method, which allows control over the shell thickness, was developed and applied to the synthesis of Ag@TiO2 and Au@TiO2 with various shell thicknesses. The morphology of the synthesized structures was investigated using scanning electron microscopy (SEM. Their sizes and shell thicknesses were determined using tunable resistive pulse sensing (TRPS technique. The optical properties of the synthesized structures were characterized using UV–vis spectroscopy. Ag@TiO2 and Au@TiO2 structures with shell thickness in the range of ≈40–70 nm and 90 nm, for the Ag and Au nanostructures respectively, were prepared using a method we developed and adapted, consisting of a change in the titania precursor concentration. The synthesized nanostructures exhibited significant absorption in the UV–vis range. The TRPS technique was shown to be a very useful tool for the characterization of metal–metal oxide core–shell nanostructures.

Organodioxygen complexes of some group 4B metal ions

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