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Effect of binders and surface finish on wear resistance of HVOF coatings

CASTELETTI, L. C.; ARNONI, E. A. B.; LOMBARDI NETO, A.; FERNANDES, F. A. P.; TOTTEN, G. E.
Fonte: MANEY PUBLISHING Publicador: MANEY PUBLISHING
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
393.1233%
The high velocity oxygen fuel (HVOF) thermal spray process produces highly wear and/or corrosion resistant coatings. Tungsten carbide with a metallic binder is often used for this purpose. In this work, tungsten carbide coatings containing cobalt or nickel binder were produced by HVOF and characterised by optical and electron microscopy, hardness and a dry sand/rubber wheel abrasion test. The HVOF process produced dense coatings with low porosity levels and high hardness. The wear resistance of the specimens, which were surface treated, increased as the roughness percentage decreased. Tungsten carbide nickel based coating yielded the best wear resistance in the as sprayed condition. However, the wear rate and wear of the two coatings converged to the same values as the number of revolutions increased. Wear behaviour in the ground condition was similar, although the tungsten carbide cobalt based coating yielded better performance with increasing distance travelled during the wear test.

Corrosion protection of aluminium alloy by cerium conversion and conducting polymer duplex coatings

Johansen, Herbert D.; Brett, Christopher M. A.; Motheo, Artur J.
Fonte: PERGAMON-ELSEVIER SCIENCE LTD; OXFORD Publicador: PERGAMON-ELSEVIER SCIENCE LTD; OXFORD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
386.83273%
The corrosion protection of AA6063 aluminium alloy by cerium conversion, polyaniline conducting polymer and by duplex coatings has been investigated. The electrochemical behaviour was evaluated in aerated 3.5 wt.% NaCl. All coatings tested shifted the corrosion and pitting potentials to more positive values, indicating protection against corrosion. The duplex coatings are significantly more effective than each coating alone: corrosion and pitting potentials were shifted by +183 and +417 mV(SCE), respectively, by duplex coatings in relation to the untreated aluminium alloy. Optical microscopy and scanning electron microscopy are in agreement with the electrochemical results, reinforcing the superior performance of duplex coatings. (C) 2012 Elsevier Ltd. All rights reserved.; Brazilian funding agency CNPq [140402/2009-8, 160466/2011-3]; Brazilian funding agency CNPq; Brazilian funding agency CAPES; Brazilian funding agency CAPES [BEX 4935/10-1]; Portuguese funding agency FCT; Portuguese funding agency FCT [CEMUC(R) (Research Unit 285)]

Computer simulation of thin film growth : applying the results to optical coatings

Sikkens, M.; Hodgkinson, I.J.; Horowitz, Flavio; Macleod, H. Angus; Wharton, J.J.
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
Relevância na Pesquisa
692.9943%
Computer simulation of thin film growth has been used extensively to gain insight into the origin and nature of the microstructure of vapor- deposited thin films. Usually, however, no attempts are made to predict film properties other than column angle and film density from such simulations. The aim of our work is to derive quantitative data from computer simulations in order to be able to predict relevant properties of optical coatings. The deposition of 2500 to 25,000 particles has been simulated on different computers by random deposition of two -dimensional hard disks, using a simple relaxation scheme. Statistical analysis of the results yields quantitative data for the density, column angle, and column period. On the basis of these results, a simple model has been developed for the microstructure of a three -dimensional film. The birefringence and the shape of water -penetration fronts in evaporated optical coatings, predicted from this model, are confirmed by experiment.

Structural electrical and optical properties of undoped and indium doped ZnO thin films prepared by the pyrosol process at different temperatures

Tokumoto, M. S.; Smith, A.; Santilli, C. V.; Pulcinelli, S. H.; Craievich, A. F.; Elkaim, E.; Traverse, A.; Briois, V
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 284-293
ENG
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466.3988%
The influence of the substrate temperature on the structural features and opto-electrical properties of undoped and indium-doped ZnO thin films deposited by pyrosol process was investigated. The addition of indium induces a drastic decrease (by a factor approximate to 10(10) for samples deposited at 300 degreesC) in the electrical resistivity of films, the lowest electrical resistivity (6 mOmega-cm) being observed for the film deposited at 450 degreesC. Films are highly transparent (>80%) in the Vis-NIR ranges, and the optical band gap exhibits a blue shift (from 3.29 to 3.33 eV) for the In-doped films deposited at increasing temperature. Preferential orientation of the ZnO crystallites with the c-axis perpendicular to the substrate surface and an anisotropic morphology of the nanoporous structure was observed for films growth at 300 and 350 degreesC. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Effects of electroplated zinc-nickel alloy coatings on the fatigue strength of AISI 4340 high strength steel

Voorwald, H. J. C.; Miguel, I. M.; Costa, M. Y. P.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 2599-2604
ENG
Relevância na Pesquisa
394.3452%
It is well known that fatigue behaviour is an important parameter to be considered in mechanical components subjected to constant and variable amplitude loadings. In combination with corrosion phenomenon, fatigue effects were responsible for proximally 64% of fails that occur in metallic parts of aeronautical accidents in the last 30 years. Recovered substrates have been extensively used in the aerospace field. Cadmium electroplating has been widely applied to promote protective coatings in aeronautical components, resulting in excellent corrosion protection combined with a good performance in cyclic loading. Ecological considerations allied to the increasing demands for corrosion resistance, resulted in the search for possible alternatives. Zinc-nickel alloys received considerable interest recently, since these coatings showed some advantages such as a good resistance to white and red rust, high plating rates and acceptation in the market. In this study the effects of zinc-nickel coatings electroplated on AISI 4340 high strength steel were analysed on rotating bending and axial fatigue strength, corrosion and adhesion resistance. Compressive residual stress field was measured by a X-ray tensometry prior to fatigue tests. Optical microscopy images showed coating thicknesses...

Solar selective absorbing coatings based on AlSiN/AlSiON/AlSiOy layers

Rebouta, L.; Sousa, A.; Andritschky, M.; Cerqueira, F.; Tavares, C. J.; Santilli, P.; Pischow, K.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2015 POR
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388.77344%
Coatings with a double absorbing layer based on AlSiN/AlSiON were deposited on stainless steel sub-strates by magnetron sputtering technique, with different Al:Si ratios. A tungsten layer was used asa back reflector and AlSiOyor SiOxthin films were used as antireflection top layers. Prior the structuredesign, several single layers were deposited on glass substrates by varying the reactive gases flows, whichallowed the stacking of a series of layers with different optical properties. Experimental transmittanceand reflectance were modelled for the assessment of the spectral optical constants, which were thenused to design a coating stack with optimized solar absorptance and thermal emittance. Optical prop-erties, microstructure, morphology, composition and chemical bonding were investigated by employingoptical spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffrac-tion and X-ray photoelectron spectroscopy. The samples were annealed in air at 400◦C and vacuum at580◦C with the purpose to evaluate their oxidation resistance and thermal stability, which was sub-sequently correlated with the Al:Si ratio. Optimum results were achieved for an Al:Si ratio of 2.3:1,whereas for significantly higher Si content resulted in detrimental performance. The solar absorbanceand thermal emittance for the optimized multilayer selective coatings is 93–94% and 7–10% (at 400◦C)...

Microstructure and Properties of Nickel-based C276 Alloy Coatings by PTA on AISI 316L and API 5L X70 Steel Substrates

Ferreira,Luciano da Silva; Graf,Karin; Scheid,Adriano
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2015 EN
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386.83273%
This work assessed Ni-based C276 alloy coatings by PTA with different degree of interaction with AISI 316L and API 5L X70 steel substrates. Track geometry, dilution and microstructure of coatings were evaluated by optical, scanning electron microscopy and X-ray diffraction. Properties were evaluated by hardness and wear tests. Microstructure exhibited austenite Ni-FCC dendrites and interdendrictic regions containing carbides. Dilution from 4,9 to 25,4% for coatings on API 5L X70 leaded to hardness ranging from 283 to 243 HV0,5. Otherwise, dilution between 22,3 and 41,5% for coatings on AISI 316L induced hardness from 267 to 225 HV0,5. Higher interaction with the substrate leaded to 19,8% increase of mass loss rate on API 5L X70 coatings. The slight difference for coatings properties deposited on different substrates indicated that the degree of interaction was the most significant factor.

Measurement of a multi-layered tear film phantom using optical coherence tomography and statistical decision theory

Huang, Jinxin; Yuan, Qun; Zhang, Buyun; Xu, Ke; Tankam, Patrice; Clarkson, Eric; Kupinski, Matthew A.; Hindman, Holly B.; Aquavella, James V.; Suleski, Thomas J.; Rolland, Jannick P.
Fonte: Optical Society of America Publicador: Optical Society of America
Tipo: Artigo de Revista Científica
Publicado em 24/11/2014 EN
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468.8204%
To extend our understanding of tear film dynamics for the management of dry eye disease, we propose a method to optically sense the tear film and estimate simultaneously the thicknesses of the lipid and aqueous layers. The proposed method, SDT-OCT, combines ultra-high axial resolution optical coherence tomography (OCT) and a robust estimator based on statistical decision theory (SDT) to achieve thickness measurements at the nanometer scale. Unlike conventional Fourier-domain OCT where peak detection of layers occurs in Fourier space, in SDT-OCT thickness is estimated using statistical decision theory directly on the raw spectra acquired with the OCT system. In this paper, we demonstrate in simulation that a customized OCT system tailored to ~1 µm axial point spread function (FWHM) in the corneal tissue, combined with the maximum-likelihood estimator, can estimate thicknesses of the nanometer-scale lipid and micron-scale aqueous layers of the tear film, simultaneously, with nanometer precision. This capability was validated in experiments using a physical phantom that consists of two layers of optical coatings that mimic the lipid and aqueous layers of the tear film.

Evaporated HfO2/SiO2 optical coatings and modifications for high-power laser applications

Oliver, James B. ; Lambropoulos, John C.
Fonte: University of Rochester Publicador: University of Rochester
Tipo: Tese de Doutorado Formato: Number of Pages:xxi, 170 leaves; Illustrations:ill. (some col.)
ENG
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605.40527%
Thesis (Ph. D.)--University of Rochester. Materials Science Program, 2012.; Evaporated optical coatings fabricated from hafnium dioxide and silicon dioxide are the standard approach for high-peak-power laser components due to the high laser damage resistance of such coatings and the ability to deposit on large-aperture substrates. The tensile film stresses of such coatings may lead to failure, however, particularly in low-relative-humidity purged or vacuum use environments. Careful control of thin-film stresses is essential to maintain high-quality surface flatness of the coated components and preserve the optical performance of the laser system. This work explores changes in the deposition process for hafnia/silica multilayer coatings in order to preserve or ideally improve the laser damage thresholds while limiting the mechanical stress in the film. Changes in the evaporation process, including deposition rate, chamber pressure, temperature, and optical coating design, were studied to evaluate their influence on the performance of the coating. Process changes were expanded to include the use of energetic plasma-assisted deposition as well as the incorporation of aluminum oxide to further alter the thin-film stress. The state of the thin-film stress...

Comparison of surface functionalization techniques on silica and soft glasses for optical fibre sensing applications

Foo, H.; François, A.; Ebendorff-Heidepriem, H.; Sumby, C.; Monro, T.
Fonte: Australian Optical Society; CDROM Publicador: Australian Optical Society; CDROM
Tipo: Conference paper
Publicado em //2009 EN
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466.3988%
We report the comparison of three different surface functionalization processes using two different organosilanes, 3-mercaptopropyltrimethoxysilane (MTS) and 3-aminopropyltriethoxysilane (APTES) and polyelectrolytes (PE) on the internal surface of tellurite, bismuth, lead silicate F2 and silica glass capillaries. We find that polyelectrolyte and organosilane coatings can be attached on the internal surfaces of the capillary of all four glass materials. Furthermore, PE provides more specific binding sites for streptavidin than MTS and APTS for all four glass materials.; Tze Cheung Foo, Alexandre François, Heike Ebendorff-Heidepriem, Christopher J. Sumby and Tanya M. Monro

Rapport M/L de disques de galaxies issus de modèles CSPE et contrôle des contraintes mécaniques dans la conception de revêtements optiques

de Denus-Baillargeon, Marie-Maude
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
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502.3052%
La thèse qui suit est organisée en deux volets: un premier volet portant sur les modèles de masse de galaxies et un second volet sur la conception de revêtements optiques et le contrôle de leurs propriétés mécaniques. Les modèles de masse présentés dans cette thèse ont été réalisés sur un sous-échantillon de dix galaxies de l'étude SINGS comprenant neuf galaxies normales et une galaxie naine. Ce travail visait à fixer le rapport masse-luminosité du disque à tout rayon en utilisant les résultats de modèles d'évolution galactique chimio-spectrophotométriques ajustés spécifiquement à chaque galaxie grâce à son profil de photométrie multi-bandes. Les résultats montrent que les disques stellaires tels que normalisés par les rapports masse-luminosité issus des modèles ont des masses cohérentes dans toutes les bandes étudiées de l'ultra-violet, du visible ainsi que du proche infrarouge (bandes FUV à IRAC2). Ces disques peuvent être considérés comme maximaux par rapport aux données cinématiques des galaxies étudiées. Ceci est dû au fait que le rapport M/L est plus élevé au centre que sur les bords. Les disques étant maximaux et physiquement justifiés, on ne peut dès lors ignorer les effets de composants tels que les bulbes ou les barres et les corrections nécessaires doivent être apportées aux profils de luminosité et de vitesses de rotation de la galaxie. Dans les travaux de la seconde partie...

Design of a superluminal ring laser gyroscope using multilayer optical coatings with huge group delay

Qu, Tianliang; Yang, Kaiyong; Han, Xiang; Wu, Suyong; Huang, Yun; Luo, Hui
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 18/11/2014 EN
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482.41676%
We propose and analyze a superluminal ring laser gyroscope (RLG) using multilayer optical coatings with huge group delay (GD). This GD assisted superluminal RLG can measure the absolute rotation with a giant sensitivity-enhancement factor of ~103; while, the broadband FWHM of the enhancement factor can reach 20 MHz. This superluminal RLG is based on a traditional RLG with minimal re-engineering, and beneficial for miniaturization according to theoretical calculation. The idea of using GD coatings as a fast-light medium will shed lights on the design and application of fast-light sensors.

Thermal noise in interferometric gravitational wave detectors due to dielectric optical coatings

Harry, Gregory M.; Gretarsson, Andri M.; Saulson, Peter R.; Penn, Steven D.; Startin, William J.; Kittelberger, Scott; Crooks, D. R. M.; Hough, Jim; Cagnoli, Gianpietro; Nakagawa, Norio; Rowan, Sheila; Fejer, Martin M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
493.1233%
We report on thermal noise from the internal friction of dielectric coatings made from alternating layers of Ta2O5 and SiO2 deposited on fused silica substrates. We present calculations of the thermal noise in gravitational wave interferometers due to optical coatings, when the material properties of the coating are different from those of the substrate and the mechanical loss angle in the coating is anisotropic. The loss angle in the coatings for strains parallel to the substrate surface was determined from ringdown experiments. We measured the mechanical quality factor of three fused silica samples with coatings deposited on them. The loss angle of the coating material for strains parallel to the coated surface was found to be (4.2 +- 0.3)*10^(-4) for coatings deposited on commercially polished slides and (1.0 +- 0.3)*10^{-4} for a coating deposited on a superpolished disk. Using these numbers, we estimate the effect of coatings on thermal noise in the initial LIGO and advanced LIGO interferometers. We also find that the corresponding prediction for thermal noise in the 40 m LIGO prototype at Caltech is consistent with the noise data. These results are complemented by results for a different type of coating, presented in a companion paper.; Comment: Submitted to LSC (internal) review Sept. 20...

Mechanical loss in state-of-the-art amorphous optical coatings

Granata, Massimo; Saracco, Emeline; Morgado, Nazario; Cajgfinger, Alix; Cagnoli, Gianpietro; Degallaix, Jérôme; Dolique, Vincent; Forest, Danièle; Franc, Janyce; Michel, Christophe; Pinard, Laurent; Flaminio, Raffaele
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/11/2015
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479.49297%
We present the results of mechanical characterizations of many different high-quality optical coatings made of ion-beam-sputtered titania-doped tantala and silica, developed originally for interferometric gravitational-wave detectors. Our data show that in multi-layer stacks (like high-reflection Bragg mirrors, for example) the measured coating dissipation is systematically higher than the expectation and is correlated with the stress condition in the sample. This has a particular relevance for the noise budget of current advanced gravitational-wave interferometers, and, more generally, for any experiment involving thermal-noise limited optical cavities.; Comment: 31 pages, 14 figures

Recubrimientos ópticos en el rango espectral entre 50 y 200 nm; Optical coatings for the spectral range 50 – 200 nm

Fernández Perea, Mónica; Méndez, José Antonio; Larruquert, Juan Ignacio; Aznárez, José Antonio
Fonte: Sociedad Española de Óptica Publicador: Sociedad Española de Óptica
Tipo: Artículo Formato: 50148 bytes; application/pdf
SPA
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700.7438%
The development of efficient optical coatings in the spectral region between 50 and 200 nm (EUV-FUV) is an important challenge due to the great absortion and low reflectance that most of the materials present in this region. In addition, these coatings are an important element in the advance of many fields like astronomical abservations, plasma diagnosis and lithography. In this work we describe some of the optical coatings developed by the Research Group in Thin Film Coatings (GOLD), which operate in the EUV-FUV region of the spectrum. In GOLD we have an ultra high vacuum experimental system that permits the deposition and in situ measurement of the transmittance and reflectance of multilayers, as a function of the angle of incidence, and in the EUV-FUV spectral range. We prepare multilayers with up to six different materials, which can be deposited using three different techniques. In situ transmittance and reflectance measurements versus the angle of incidence permits the determination of the optical constants (n,k) of the materials, without being exposed to the atmosphere. Due to the great dependance between the optical properties of thin film layers in this spectral range, and the exposition to the atmosphere, our experimental system is a very adequate tool for the determination of those properties...

Spectral pH dependence of erythrosin B in sol-gel silica coatings and buffered solutions; Dependencia espectral de la eritrosina B con el pH en soluciones tampón y en recubrimientos sol-gel de silice

Montero, E. F.; García, M. A.; Villegas Broncano, María Ángeles; Llopis, J.
Fonte: Sociedad Española de Cerámica y Vidrio Publicador: Sociedad Española de Cerámica y Vidrio
Tipo: Artículo Formato: 656713 bytes; application/pdf
ENG
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399.48%
[EN] Thin coatings optically sensitive against pH are obtained by entrapping erythrosin B molecules in a sol-gel silica matrix. Comparisons between optical spectra of erythrosin B in solutions and those once entrapped in silica coatings are performed for pH ranging from 0.5 to 12.0. Significant differences between both kinds of spectra (solutions and coatings) of erythrosin B are observed. Main changes are displayed in the absorption spectra for neutral to basic pH. Furthermore, the erythrosin B doped coatings show memory effect or hysteresis in their spectral response against pH. This means that absorption spectra depend on the direction of the pH change. Likewise, the photoluminescent spectra of erythrosin B in buffered solutions exhibit pH dependence and a maximized response in the basic pH range. On contrast, no significant photoluminescence from the erythrosin B entrapped in the silica coatings is observed. Results are mainly discussed on the basis of different optical response of polyprotic forms of erythrosin B and possible interactions between the molecule and oxygen as well as the porous walls of the sol-gel silica matrix. In addition, the presence of diffusional barriers, which hamper the flowing of protons and other associated ions...

Nondestructive evaluation of Polymer Coating Structures on Pharmaceutical Pellets using Full Field Optical Coherence Tomography

Li, C.; Zeitler, J. Axel; Dong, Y.; Shen, Y.-C.
Fonte: Wiley Publicador: Wiley
Tipo: Article; accepted version
EN
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388.77344%
This is the pre-peer reviewed version of the following article: Li, C., Zeitler, J. A., Dong, Y. and Shen, Y.-C. (2014), Non-Destructive Evaluation of Polymer Coating Structures on Pharmaceutical Pellets Using Full-Field Optical Coherence Tomography. J. Pharm. Sci., 103: 161-166. doi: 10.1002/jps.23764, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/jps.23764/abstract; The full text of this article is embargoed until 2015-01-31 in accordance with the publisher's policy; Full field optical coherence tomography (FF-OCT) using a conventional LED light source and a CMOS camera has been developed for characterising coatings on small pellet samples. A set of en-face images covering an area of 700?m x 700?m were taken over a depth range of 166 ?m. The three-dimensional structural information, such as the coating thickness and uniformity, was subsequently obtained by analysis of the recorded en-face images. Drug loaded pharmaceutical sustained release pellets with two coating layers and of a sub-millimetre diameter were studied to demonstrate the usefulness of the developed system. We have shown that both coatings can be clearly resolved and the thickness was determined to be 40 ?m and 50 ?m for the outer and inner coating layers...

Thermal noise from optical coatings in gravitational wave detectors

Harry, Gregory M.; Armandula, Helena; Black, Eric; Crooks, D. R. M.; Cagnoli, Gianpietro; Hough, Jim; Murray, Peter; Reid, Stuart; Rowan, Sheila; Sneddon, Peter; Fejer, Martin M.; Route, Roger; Penn, Steve D.
Fonte: Optical Society of America Publicador: Optical Society of America
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em 01/03/2006
Relevância na Pesquisa
588.77344%
Gravitational waves are a prediction of Einstein's general theory of relativity. These waves are created by massive objects, like neutron stars or black holes, oscillating at speeds appreciable to the speed of light. The detectable effect on the Earth of these waves is extremely small, however, creating strains of the order of 10−21. There are a number of basic physics experiments around the world designed to detect these waves by using interferometers with very long arms, up to 4 km in length. The next-generation interferometers are currently being designed, and the thermal noise in the mirrors will set the sensitivity over much of the usable bandwidth. Thermal noise arising from mechanical loss in the optical coatings put on the mirrors will be a significant source of noise. Achieving higher sensitivity through lower mechanical loss coatings, while preserving the crucial optical and thermal properties, is an area of active research right now.

Optical properties of an ormosil system comprising methyl- and phenyl-substituted silica

Atkins, Graham; Krolikowska, Maryla; Samoc, Anna
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
470.46082%
We report an organically modified silica (ormosil) system in which the refractive index can be varied from 1.40 to 1.55 by modifying the silica backbone with phenyl and methyl groups, which increase and decrease the refractive index, respectively. By changing the quantities of the phenyl- and methyl-modified precursors in the sol-gel mixture, the refractive index can be varied while keeping the organic fraction of the material constant. Crack-free, dried films up to 15-μm thick have been coated onto silicon and glass substrates, with potential application to optical waveguides for planar integrated circuits. The contributions of SiO-H and C-H absorptions to the attenuation in the communications windows are discussed, along with factors affecting the homogeneity and cracking tendency of the ormosils.

Structural characterization, optical response, and corrosion resistance of bismuth coatings

Alfonso,José E; Olaya,Jhon J; Ortiz,María F
Fonte: Universidad Simón Bolívar; ; Publicador: Universidad Simón Bolívar; ;
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2014 EN
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400.70195%
We present the results obtained from the deposition of nanostructure bismuth coatings through DC pulsed unbalanced magnetron sputtering. The Bi coatings were deposited simultaneously on common glass, silicon, and Ti6AL4V substrates in order to evaluate the optical properties, morphology, and microstructure as a function of the pulsed frequency deposition, and to establish the relationship between these properties and corrosion resistance. The microstructure was evaluated via X-ray diffraction (XRD), and the morphology of the coatings was evaluated through scanning electron microscopy (SEM) and atomic force microscopy (AFM). Optical properties were characterized through absorbance and transmittance spectra. The XRD analysis indicated that the coatings are polycrystalline. The SEM micrographs showed that the coatings are grown as droplets form. AFM revealed roughness values from 20.0 to 28.8 nm. Finally, from the optical measurements, it was possible to establish the band-gap energy of the Bi coatings.