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Oxide Films (oxide + film)
Kinds of Oxide Films Selected AbstractsMultiwalled Carbon Nanotubes Encased in Ruthenium Oxide Film as a Hybrid Material for Neurotransmitters SensorELECTROANALYSIS, Issue 16 2009Chien-Chieh Ti Abstract A hybrid film (MWCNTs-RuOx,nH2O) which contains multiwalled carbon nanotubes (MWCNTs) along with the incorporation of ruthenium oxide (RuOx,nH2O) has been synthesized on glassy carbon electrode (GCE), gold (Au), indium tin oxide (ITO) and screen printed carbon electrode (SPCE) by potentiostatic methods. The presence of MWCNTs in the hybrid film enhances surface coverage concentration (,) of RuOx,nH2O to ,2100%. The surface morphology of the hybrid film deposited on ITO has been studied using scanning electron microscopy and atomic force microscopy. These two techniques reveal that the RuOx,nH2O incorporated on MWCNTs. Electrochemical quartz crystal microbalance study too reveals the incorporation of MWCNTs and RuOx,nH2O. The MWCNTs-RuOx,nH2O hybrid film exhibits promising enhanced electrocatalytic activity towards the biochemical compounds such as epinephrine and norepinephrine. The electrocatalytic responses of these analytes at RuOx,nH2O, MWCNTs and MWCNTs-RuOx,nH2O hybrid films have been measured using cyclic voltammetry. The obtained sensitivity values from electrocatalysis studies of analytes for MWCNTs-RuOx,nH2O hybrid film are higher than the RuOx,nH2O and MWCNTs films. Finally, the flow injection analysis has been used for the amperometric studies of analytes at MWCNTs-RuOx,nH2O hybrid film modified SPCEs. [source] Transparent and Conductive Polyethylene Oxide Film by the Introduction of Individualized Single-Walled Carbon NanotubesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 24 2009Yong Chae Jung Abstract It is demonstrated that an optically transparent and electrically conductive polyethylene oxide (PEO) film is fabricated by the introduction of individualized single-walled carbon nanotubes (SWNTs). The incorporated SWNTs in the PEO film sustain their intrinsic electronic and optical properties and, in addition, the intrinsic properties of the polymer matrix are retained. The individualized SWNTs with smaller diameter provide high transmittance as well as good electrical conductivity in PEO films. [source] An X-ray Spectromicroscopy Study of Albumin Adsorption to Crosslinked Polyethylene Oxide Films,ADVANCED ENGINEERING MATERIALS, Issue 5 2010Bonnie O. Leung Abstract Synchrotron-based X-ray photoemission electron microscopy (X-PEEM) is used to characterize the near surface composition of polyethylene oxide (PEO) combined with 1.5, 5, and 10,wt.-% pentaerythritol triacrylate (PETA) crosslinker. It is found that as the concentration of PETA increases, it becomes the dominant component in the top 10,nm of the film surface. The same surfaces are also exposed to human serum albumin (HSA) and the distributions of the protein relative to PEO and PETA measured with X-PEEM. A positive correlation is found between levels of PETA and HSA at the surface. Above PETA concentrations of 5,wt.-%, HSA adsorption is significant, which suggests high levels of PETA (often used to immobilize PEO by crosslinking) can significantly reduce the non-fouling properties of PEO. [source] In-Situ Studies of ALD Growth of Hafnium Oxide Films,ADVANCED ENGINEERING MATERIALS, Issue 4 2009Konstantin Karavaev We investigated in situ the atomic layer deposition is of the high- k dielectric material HfO2. We used X-ray photoelectron spectroscopy and ultra high vacuum atomic force microscopy for characterizing both the thin film and the substrate. With this technique, we determined the growth and the chemical-physical properties of the thin film. [source] Patterned Graphene Electrodes from Solution-Processed Graphite Oxide Films for Organic Field-Effect TransistorsADVANCED MATERIALS, Issue 34 2009Shuping Pang A replacement for gold as the hole-injecting metal in organic electronic devices is presented: patterned graphene electrodes prepared from graphite oxide sheets by oxygen plasma etching. Solution-processed organic FETs with poly(3-hexylthiophene) as the semiconductor and these graphene electrodes are shown to perform as well as or even better than devices with gold contacts. [source] Photoinduced Formation of Wrinkled Microstructures with Long-Range Order in Thin Oxide Films,ADVANCED MATERIALS, Issue 24 2007M. Takahashi Thin oxide films with long-range ordered microstructures were fabricated by a wrinkling process initiated by photopolymerization. The faster polymerization of the film surface generates a buckling effect to create patterns in the films. The removal of the organic polymer by thermal treatment leaves titania microstructures having long-range order. This method of producing micropatterned structures can find several applications in photonics. [source] On-Site Fabrication of Crystalline Cerium Oxide Films and Patterns by Ink-Jet Deposition Method at Moderate TemperaturesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2008Ruwan Gallage Crystalline CeO2 films and patterns have been successfully fabricated in a "single-step process" at moderate temperature. In this process, the combination of the ink-jet technique and depositing the precursor on a hot substrate (,300°C) gave crystalline CeO2 without further heat treatment. X-ray diffraction analysis revealed that the phase formed was crystallized ceria with nanosized (<10 nm) crystallites. The film thickness was several hundred nanometers and the pattern width was about 150 ,m. Scanning electron microscopy analysis showed that the films and patterns were free of cracks and adhered to the substrate. This is the first report about the direct patterning of crystalline CeO2 without postfiring or posttreatments like masking, etching, etc. [source] The Interplay between Structure and CO Oxidation Catalysis on Metal-Supported Ultrathin Oxide Films,ANGEWANDTE CHEMIE, Issue 26 2010Ying-Na Sun Günstige Lage: Ultradünne Oxidfilme auf Metallen können die katalytische Aktivität stark erhöhen, z.,B. bei der CO-Oxidation an einem FeO(111)-Film auf Pt(111). Unter den Reaktionsbedingungen lagert sich der zweilagige FeO-Film zu einem dreilagigen OFeO-Film um (siehe Bild). Neben experimentellen Befunden zur Struktur und Morphologie des Films wird eine theoretische Modellierung des Filmbildungsmechanismus und der CO-Oxidation auf der Oberfläche vorgestellt. [source] Growth and Properties of TiCl4 -Derived CVD Titanium Oxide Films at Different CO2/H2 Inputs,CHEMICAL VAPOR DEPOSITION, Issue 5 2003D.-H. Kuo Abstract Crystalline titanium oxide films with a thickness of 0.09,0.55,,m were prepared at temperatures below 500,°C by CVD using a mixture of titanium tetrachloride (TiCl4), carbon dioxide (CO2), and hydrogen (H2) as reactants. Film thickness decreased with increasing substrate temperature and CO2/H2 input. Nanosized microstructure was obtained at high CO2/H2 input due to the growth retardation of reacted HO-TiCl3* by the unreacted TiCl4 and CO2. That film composition, i.e., the O/Ti ratio, increased with temperature and the CO2/H2 input can be explained by growth kinetics. Unlike film thickness, internal film stress increased with increasing substrate temperature. Adhesion was controlled by compressive internal stress due to the weak bonding between film and substrate. Two growth mechanisms are proposed to explain the tensile and compressive stress states in films produced by CVD. The adsorption-controlled reaction has a film in compressive stress that increases with an increase in temperature. On the other hand, thermally activated CVD produces a film in tensile stress that decreases with an increase in substrate temperature. [source] Efficient Reduction of Graphite Oxide by Sodium Borohydride and Its Effect on Electrical ConductanceADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Hyeon-Jin Shin Abstract The conductivity of graphite oxide films is modulated using reducing agents. It is found that the sheet resistance of graphite oxide film reduced using sodium borohydride (NaBH4) is much lower than that of films reduced using hydrazine (N2H4). This is attributed to the formation of CN groups in the N2H4 case, which may act as donors compensating the hole carriers in reduced graphite oxide. In the case of NaBH4 reduction, the interlayer distance is first slightly expanded by the formation of intermediate boron oxide complexes and then contracted by the gradual removal of carbonyl and hydroxyl groups along with the boron oxide complexes. The fabricated conducting film comprising a NaBH4 -reduced graphite oxide reveals a sheet resistance comparable to that of dispersed graphene. [source] Preparation and Electrical Properties of an Anodized Al2O3,BaTiO3 Composite FilmJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2008Xianfeng Du A highly stable, water-based barium titanate BaTiO3, BT, sol was synthesized using a sol,gel route through a chelate lactate technique. Dried BT precursor powders were measured by thermal gravimetry,differential thermal analysis and X-ray diffraction. It was found that BT powders first converted into barium carbonate BaCO3, Ti complex, and intermediate phase Ba2Ti2O5CO3, and then transformed into perovskite phase BaTiO3. The crystallization temperature was about 550°C. The low-voltage etched aluminum foils were covered with BT sol by dip coating, and then annealed at 600°C for 30 min in air. After that, the samples were anodized in a 15 wt% aqueous solution of ammonium adipate. The voltage,time variations during anodizing were monitored, and the electrical properties of the anodic oxide film were examined. It was shown that the specific capacitance, the product of specific capacitance and withstanding voltage, and leakage current of samples with a BT coating were about 48.93%, 38.50%, and 167% larger than that without a BT coating, respectively. [source] Critical Factors Affecting the Wettability of ,-Alumina by Molten AluminumJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2004Ping Shen The wetting behaviors of ,-Al2O3 single crystals with three different faces,R(0112), A(01120), and C(0001),and polycrystals (PC) by molten aluminum were studied over a wide temperature range using both a conventional and an improved sessile-drop method. The critical factors affecting the wettability, such as temperature, atmosphere, substrate surface roughness, and crystallographic orientation, and the influence from the experimental technique, were thoroughly investigated. The results show that the aluminum surface oxidation and the thickness of the oxide film have a pronounced effect on the wettability, especially at low temperatures. To eliminate this effect, the experimental temperature must be over a critical value. Vacuum favors lowering this value compared with atmosphere, and the improved sessile-drop method, particularly using an impingement-dropping mode (I-mode), helps to weaken this effect by mechanical disruption and removal of the oxide film. However, the dropping distance and the dropping force must be controlled to prevent an overspreading of the drop. The effects of the substrate surface roughness and temperature are not significant in the case of a clean aluminum surface and a fine-prepared alumina surface. On the other hand, the effect of the alumina surface crystallographic orientation is noticeable and the wettability is in the order of R > A > PC > C. The intrinsic contact angles of the Al/,-Al2O3 system in the temperature range of 1000°,1500°C were estimated to be 76°,85° for the R and A faces, 88°,100° for the C face, and 77°,90° for the polycrystal, depending on the temperature. [source] Evaluation of different sealing methods for anodized aluminum-silicon carbide (Al/SiC) composites using EIS and SEM techniquesMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 11 2007H. Herrera-Hernandez Electrochemical impedance spectroscopy (EIS) and the scanning electron microscope (SEM) have been used in an investigation of the effectiveness of various sealing methods that can be used to improve the corrosion resistance of an anodized aluminum-silicon carbide (Al/SiC) composite. Anodic oxide films were grown on Al7075-T6 and the Al/SiC composite by sulfuric acid anodizing and sealing in a cold saturated solution of nickel acetate. Other samples were sealed using the traditional method of boiling water or hot nickel acetate for comparison. The results revealed a uniform anodized layer on Al7075-T6 that resisted pitting corrosion for more than 2,weeks exposure to NaCl, whereas a cracked oxide film with variations in thickness was observed on the composite material. Pit initiation occurred in less than 5,days on the anodized Al/SiC that was sealed in the hot solutions. This study suggests that the traditional hot sealing methods did not provide sufficient corrosion protection for aluminum metal,matrix composites (MMCs) because the reinforcing SiC particles deteriorated the surface film structure. However, this defective film can be repaired by nickel hydrate precipitation during cold sealing or by applying a thick polyurethane coating. [source] Resistance monitoring of aluminum plates to microbiologically influenced corrosion using FFT impedance spectroscopy methodsMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 7 2006P. Norouzi Abstract It is well know that formation of a passive oxide film on aluminum can enhance its corrosion resistance. However, microbiologically species are able to damage this film. Microbial adhesion is widely accepted as important stage prior to the induction or initiation of biocorrosion. Pseudomonas aeruginosa and Cladosprioum sp. have been commonly associated with the microbiologically influenced corrosion (MIC) of aluminum and its alloys. In this study, the effect of an organic dye (Quinizarin), on the resistance of aluminum plates to MIC has been investigated by some corrosion monitoring methods such as FFT impedance spectroscopy, cyclic voltammetry and SEM (scanning electron microscopy). In this work, the surface of aluminum plates were changed after exposing them (five types: only polished, anodized, anodized and colored, anodized and colored and sealed) to Pseudomonas aeuroginosa in ASW (artificial sea water) as a microbial culture. The results showed that, the mentioned color caused a decrease in the growth of bacteria, because the color acts a protected layer on the surface of aluminum. This characteristic can reduce intensity of biocorrosion on aluminum plates, so the anodized and colored and sealed plates have the most resistance to MIC, and it can be shown and proven by these techniques which are mentioned above. [source] Anodic oxides on a beta type Nb,Ti alloy and their characterization by electrochemical impedance spectroscopyPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2010Michael Teka Woldemedhin Abstract Anodic oxides were grown on the surface of an electropolished (Ti,30,at% Nb) beta-titanium (,-Ti) alloy by cyclic voltammetry. The scan rate was 100,mV,s,1 between 0 and 8,V in increments of l,V in an acetate buffer of pH 6.0. Electrochemical impedance spectroscopy was carried out right after each anodic oxide growth increment to study the electronic properties of the oxide/electrolyte interface in a wide frequency range from 100,kHz to 10,MHz with an AC perturbation voltage of 10,mV. A film formation factor of 2.4,nm,V,1 was found and a relative permittivity number (dielectric constant) of 42.4 was determined for the oxide film formed. Mott,Schottky analysis on a potentiostatically formed 7,nm thick oxide film was performed to assess the semiconducting properties of the mixed anodic oxide grown on the alloy. A flat band potential of ,0.47,V (standard hydrogen electrode, SHE) was determined, connected to a donor density of 8.2,×,1017,cm,3. ,-Ti being highly isotropic in terms of mechanical properties should be superior to the stiffer ,-Ti compound. Its application, however, requires a passivation behaviour comparable or better than ,-Ti which in fact is found. [source] In situ ellipsometric studies of formation kinetics of rare earth metal conversion coatings on magnesium alloyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 5 2008Lingjie Li Abstract In situ spectroscopic ellipsometry was employed to investigate the initial regime of rare earth metal (REM) conversion coatings formation on AZ31 magnesium alloy. Three REM salts solutions, 0.05 mol·dm -3 Ce(NO3)3, La(NO)3 and Sm(NO)3 solutions, were used for REM conversion coatings preparation. By deconvoluting the ellipsometric data, the surface of the fresh well-polished AZ31 magnesium alloy was found to be covered with 15.80 nm thick native (hydr)oxide film; the refractive indices and the thickness of Ce, La and Sm conversion coatings were obtained. The formation kinetics of three REM coatings follows different exponential functions and the coatings exhibit different optical properties. La conversion coating has the largest n values and the lowest k values while Sm conversion coating is just opposite. Moreover, the pH variation of the bulk conversion solutions upon the coatings formation was recorded. It is confirmed that the reduction of protons leads to the interfacial pH increasing and further results in the precipitation of REM hydroxide gel, which is critical for the REM conversion coatings formation. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Oxidation-induced high-Curie-temperature ferromagnetism in CoAl(100)PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2007V. Rose Abstract In conventional magnetic materials, oxidation is a disagreeable effect that often lowers or destroys the magnetic capabilities of those materials. By contrast, we report on the decisive paramagnetic-ferromagnetic phase transition in CoAl(100) at room temperature, utilizing oxidation of stoichiometric CoAl. We also discuss the control and drastic increase of the coercive field by subsequent annealing of the oxidized sample. The alumina film grown by selective oxidation protects the alloy from oxidation of Co, despite the accumulation of Al vacancies and the resulting enrichment in Co of the metallic phase underneath the oxide film. As a result, a ferromagnetic thin Co-rich phase is formed at the interface between the insulating aluminum oxide and the paramagnetic Co50Al50 bulk. The creation via simple oxidation of a ferromagnetic thin film underneath a surface insulator demonstrates a novel path to building the majority of a magnetic tunnel junction. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Anodic oxide films on silicon carbideCRYSTAL RESEARCH AND TECHNOLOGY, Issue 11 2007S. K. Lilov Abstract Anodic oxide films were grown on SiC using various electrolytes. The obtained oxide films were compared and some of their electrophysical properties were investigated. Anodic oxidation of SiC was shown to be useful for precise removal of layers as well as for identification of the polar faces of SiC crystals. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Heat treatment induced structural and optical properties of rf magnetron sputtered tantalum oxide filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2007S. V. Jagadeesh Chandra Abstract Rf magnetron sputtering technique was employed for preparation of tantalum oxide films on quartz and crystalline silicon (111) substrates held at room temperature by sputtering of tantalum in an oxygen partial pressure of 1x10 -4 mbar. The films were annealed in air for an hour in the temperature range 573 , 993 K. The effect of annealing on the chemical binding configuration, structure and optical absorption of tantalum oxide films was systematically studied. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Influence of Surface Chemistry and Pore Size on the Adsorption of Proteins on Nanostructured Carbon MaterialsADVANCED FUNCTIONAL MATERIALS, Issue 15 2010Munusami Vijayaraj Abstract Carbon films are synthesized by templating of anodic aluminum oxide films. These carbon materials exhibit nanochannels with controlled diameter and length. Selected chemical treatments are done to tailor the surface chemistry. The adsorption capacities of bovine serum albumin and cytochrome c are measured by temperature-programmed desorption with mass spectrometry (TPD-MS) analysis and with conventional biological assays. The first method allows quantification of the proteins that exhibit strong interactions with the surface, while the second one is used to obtain the total adsorption capacity. Moreover, the TPD-MS profiles, which are related to the structural modifications of the proteins during the adsorption, show that strong interactions take place with hydrophobic surfaces. When oxygenated functions are present, the adsorption capacity increases and the nature of the interactions is modified. The ratio of irreversible to reversible adsorption is significantly different for the two proteins, and is slightly related to the surface chemistry. The influence of nanochannel size is studied: below 50 nm, the coverage ratio shows that access to the porosity is limited by diffusion in the channel and by pore plugging, in agreement with the strong interactions of proteins with the carbon surface. [source] Efficient Reduction of Graphite Oxide by Sodium Borohydride and Its Effect on Electrical ConductanceADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Hyeon-Jin Shin Abstract The conductivity of graphite oxide films is modulated using reducing agents. It is found that the sheet resistance of graphite oxide film reduced using sodium borohydride (NaBH4) is much lower than that of films reduced using hydrazine (N2H4). This is attributed to the formation of CN groups in the N2H4 case, which may act as donors compensating the hole carriers in reduced graphite oxide. In the case of NaBH4 reduction, the interlayer distance is first slightly expanded by the formation of intermediate boron oxide complexes and then contracted by the gradual removal of carbonyl and hydroxyl groups along with the boron oxide complexes. The fabricated conducting film comprising a NaBH4 -reduced graphite oxide reveals a sheet resistance comparable to that of dispersed graphene. [source] A Highly Sensitive Hybrid Colorimetric and Fluorometric Molecular Probe for Cyanide Sensing Based on a Subphthalocyanine Dye,ADVANCED FUNCTIONAL MATERIALS, Issue 9 2006E. Palomares Abstract A highly sensitive, selective colorimetric and fluorometric molecular probe based on a subphthalocyanine dye has been developed for cyanide-anion determination in aqueous solution. It has also been shown that a carboxysubphthalocyanine derivative can be covalently anchored to transparent mesoporous nanocrystalline high-surface-area metal oxide films to detect low concentrations of cyanide anion in pure water with no interference from other anionic or cationic species. [source] Perfect Bi4Ti3O12 Single-Crystal Films via Flux-Mediated Epitaxy,ADVANCED FUNCTIONAL MATERIALS, Issue 4 2006R. Takahashi Abstract Excellent crystallinity of material films and atomic control of their surface/interface, sufficient for the realization of their optimal physical properties, are technological premises for modern functional-device applications. Bi4Ti3O12 and related compounds attract much interest as highly insulating, ferroelectric materials for use in ferroelectric random-access memories. However, it has been difficult thus far for Bi4Ti3O12 films to satisfy such requirements when formed using vapor-phase epitaxy, owing to the high volatility of Bi in a vacuum. Here, we demonstrate that flux-mediated epitaxy is one of the most promising and widely applicable concepts to overcome this inevitable problem. The key point of this process is the appropriate selection of a multi-component flux system. A combinatorial approach has led to the successful discovery of the novel flux composition of Bi,Cu,O for Bi4Ti3O12 single-crystal film growth. The perfect single-crystal nature of the stoichiometric Bi4Ti3O12 film formed has been verified through its giant grain size and electric properties, equivalent to those of bulk single crystals. This demonstration has broad implications, opening up the possibility of preparing stoichiometric single-crystal oxide films via vapor-phase epitaxy, even if volatile constituents are required. [source] Characteristics of CVD silicon oxide films: Effect of discharge form on formation and properties of filmsHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 2 2004Kazuhiro Ishimaru Abstract A silent discharge is one of the simplest methods for realizing a nonequilibrium plasma condition at atmospheric pressure. In this study, nonequilibrium plasma chemical reactions by this discharge have been applied to a remote plasma chemical vapor deposition (CVD) of silicon oxide films using tetraethylorthosilicate (TEOS) and oxygen. Film characteristics obtained by this CVD have been investigated for applications to advanced semiconductor devices. Conditions for depositing films with high quality have been investigated minutely. From these results, it has been clarified that silicon oxide films with high quality and excellent step coverage can be obtained by plasma excitation using pulsed silent discharge. It has also been clarified that films with similar characteristics can be obtained by plasma excitation using low-frequency AC silent discharge at subatmospheric pressure. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(2): 106,116, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20000 [source] Microelectromechanical Systems: All-Oxide Crystalline Microelectromechanical Systems: Bending the Functionalities of Transition-Metal Oxide Thin Films (Adv. Mater.ADVANCED MATERIALS, Issue 23 200923/2009) Freestanding structures can be employed to induce strain at their surfaces upon bending. Luca Pellegrino and co-workers show on p. 2377 that a crystalline SrTiO3 (001) thin film cantilevered structure that can be used as a flexible substrate for the epitaxial deposition of correlated oxide films. Surface strain generated by bending is transmitted to the epitaxial (La,Sr)MnO3 film producing a reversible change of its electrical resistance. [source] All-Oxide Crystalline Microelectromechanical Systems: Bending the Functionalities of Transition-Metal Oxide Thin FilmsADVANCED MATERIALS, Issue 23 2009Luca Pellegrino A crystalline all-oxide microelectromechanical system is presented. A suspended SrTiO3(001) cantilever is employed as flexible substrate for the deposition of epitaxial transition-metal oxide films. A strain generator device for oxide films is thus demonstrated, changing the conductivity of an overgrown epitaxial (La,Sr-)-MnO3 film by bending downward the SrTiO3 element with an AFM tip or a gate voltage bias. [source] Photoinduced Formation of Wrinkled Microstructures with Long-Range Order in Thin Oxide Films,ADVANCED MATERIALS, Issue 24 2007M. Takahashi Thin oxide films with long-range ordered microstructures were fabricated by a wrinkling process initiated by photopolymerization. The faster polymerization of the film surface generates a buckling effect to create patterns in the films. The removal of the organic polymer by thermal treatment leaves titania microstructures having long-range order. This method of producing micropatterned structures can find several applications in photonics. [source] Two-dimensional small-angle X-ray scattering of self-assembled nanocomposite films with oriented arrays of spheres: determination of lattice type, preferred orientation, deformation and imperfectionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2007Bernd M. Smarsly Mesostructured oxide films were prepared by dip-coating from colloidal solutions on ultrathin Si wafers and solidified by heating at various temperatures. Two-dimensional small-angle X-ray scattering measurements were carried out in transmission under selected tilt angles and evaluated by comparison with analytical expressions. The films are composed of oriented mesophases, the structures of which are defined in terms of lattice type, preferred orientation, deformation and imperfection, notably stacking faults. [source] Evaluation of different sealing methods for anodized aluminum-silicon carbide (Al/SiC) composites using EIS and SEM techniquesMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 11 2007H. Herrera-Hernandez Electrochemical impedance spectroscopy (EIS) and the scanning electron microscope (SEM) have been used in an investigation of the effectiveness of various sealing methods that can be used to improve the corrosion resistance of an anodized aluminum-silicon carbide (Al/SiC) composite. Anodic oxide films were grown on Al7075-T6 and the Al/SiC composite by sulfuric acid anodizing and sealing in a cold saturated solution of nickel acetate. Other samples were sealed using the traditional method of boiling water or hot nickel acetate for comparison. The results revealed a uniform anodized layer on Al7075-T6 that resisted pitting corrosion for more than 2,weeks exposure to NaCl, whereas a cracked oxide film with variations in thickness was observed on the composite material. Pit initiation occurred in less than 5,days on the anodized Al/SiC that was sealed in the hot solutions. This study suggests that the traditional hot sealing methods did not provide sufficient corrosion protection for aluminum metal,matrix composites (MMCs) because the reinforcing SiC particles deteriorated the surface film structure. However, this defective film can be repaired by nickel hydrate precipitation during cold sealing or by applying a thick polyurethane coating. [source] Testing procedure to obtain reliable potentiodynamic polarization curves on type 310S stainless steel in alkali carbonate meltsMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 4 2006S. Frangini Abstract Potentiodynamic polarization measurements have been employed to evaluate the anodic behavior of a type 310S stainless steel in the eutectic Li/K molten carbonate. In general, the electrochemical tests yield useful information to predict the stability of the oxide films formed on the surface at the initial period of corrosion, although some precaution is required in the testing procedure as the reproducibility of results is seen to be adversely affected by the passage of large currents. Especially when the steel is in a passive state, erratic results are easily observed if the corrosion layer is being damaged by uncontrolled large currents. This is because the acid-base properties of the melt are susceptible to deep changes by applied currents in the milli-ampere range resulting in hysteresis phenomena in the polarization plot. Hysteresis is caused, on one hand, by acidic dissolution of the passive layer at high anodic currents and, on the other hand, by increased melt basicity due to oxide ion build-up at high cathodic currents. An optimized testing procedure is therefore suggested that minimizes these effects by imposing a 2 mA/cm2 threshold current during polarization measurements. Moreover, the conditions for the applicability of the linear polarization technique to estimate kinetic parameters have been discussed in relationship with the corrosion mechanisms analysed by impedance spectra. It is concluded that the presence of diffusional impedance terms and formation of surface resistive films in molten carbonates may result in not reliable polarization resistance values obtained with the linear polarization. [source] | ||||||||||||||||||||||||||||