莫来石抗氧化外涂层的制备及抗氧化性能

以莫来石粉体(3Al2O3·2SiO2)为原料,采用水热电泳沉积法在C/C-SiC复合材料表面制备了莫来石外涂层。借助XRD和SEM等对涂层的晶相组成和显微结构进行了表征。研究了水热沉积电压对莫来石外涂层相组成、形貌及高温抗氧化性能的影响。结果表明:外涂层主要由莫来石晶相组成。当沉积电压控制在120~180 V范围内时,莫来石外涂层的致密程度、厚度及抗氧化性能随着沉积电压的升高而提高。当沉积电压达到210 V时,制备的外涂层出现疏松、裂纹等缺陷,抗氧化性能减弱。抗氧化测试表明与包埋法制备的SiC-C/C涂层试样相比,莫来石-SiC-C/C涂层试样的抗氧化性能明显提高。当沉积电压为180 V时,制备的复合涂层试样可在1500℃的空气气氛下有效保护C/C复合材料164 h,其失重仅为1.75%。     

Prepolymer film growth by adsorption out of solution on silicon and aluminium

A cyanurate prepolymer has been applied to smooth silicon wafers or to distinctly structured aluminium coatings. The surface composition of the substrates has been investigated by X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and ellipsometry. The application methods, spin coating and dip coating represent adsorption by a technical process exerting significant shear stresses or nearly equilibrated conditions, respectively. The mean tickness of the prepolymer film has been adjusted by variation of the concentration of the solution and checked by ellipsometry. Atomic Force Microscopy (AFM) monitored the development of the respective film morphologies of all 4 systems (silicon/aluminium, spin/dip coating) in the mean film thickness range from 1 to 50 nm.     

Prepolymer film growth by adsorption out of solution on silicon and aluminium

A cyanurate prepolymer has been applied to smooth silicon wafers or to distinctly structured aluminium coatings. The surface composition of the substrates has been investigated by X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and ellipsometry. The application methods, spin coating and dip coating represent adsorption by a technical process exerting significant shear stresses or nearly equilibrated conditions, respectively. The mean tickness of the prepolymer film has been adjusted by variation of the concentration of the solution and checked by ellipsometry. Atomic Force Microscopy (AFM) monitored the development of the respective film morphologies of all 4 systems (silicon/aluminium, spin/dip coating) in the mean film thickness range from 1 to 50 nm.     

Synthesis,analytical characterization and bioactivity of Ag and Cu nanoparticles embedded in poly-vinyl-methyl-ketone films

The electrosynthesis of copper and silver core-shell nanoparticles (NPs) by the sacrificial anode technique, employing tetraoctylammonium (TOA) salts as base electrolyte for the first time, is described. These surfactants were selected because they combine high NP stabilizing power with useful disinfecting properties. The resulting colloids were mixed with a solution of an inert dispersing polymer and used to prepare nanostructured composite thin films. The morphologies and chemical compositions of the nanomaterials were characterized by Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The TEM reveals that the average core diameter of the metal NPs ranges between 1.7 and 6.3 nm, as a function of the nature of the metal and of the electrosynthesis conditions, and does not change significantly upon inclusion in the polymer matrix. An appreciable concentration of the metal is detected on the nanoparticle surface by XPS. High-resolution XP spectra indicate that both copper and silver are present at zero oxidation state in all of the materials (colloids and composite films). This demonstrates the high efficiency of the surfactant at controlling the morphology and the chemical composition of the nanodispersed metal in both the as-synthesized colloid and in the polymeric dispersion. The nanocoatings are shown to exert a marked inhibitory effect on the growth of eukaryote and prokaryote target microrganisms, and experimental evidence of a synergic disinfecting effect due to the surfactant and the nanodispersed metal is provided. On the basis of these stability and bioactivity results, it is clear that Cu-NPs and Ag-NPs are suitable for application in disinfecting or antifouling paint and coating formulations.Electronic Supplementary Material Supplementary material is available for this article at Dedicated to the memory of Wilhelm Fresenius     

Inhibition effect of cerium in hybrid sol–gel films on aluminium alloy AA2024

Aluminium alloys such as AA2024 are susceptible to severe corrosion attack in aggressive solutions (e.g. chlorides). Conversion coatings, like chromate, or rare earth conversion coatings are usually applied in order to improve corrosion behaviour of aluminium alloys. Methacrylate‐based hybrid films deposited with sol–gel technique might be an alternative to conversion coatings. Barrier properties, paint adhesion and possibly self‐healing ability are important aspects for replacement of chromate‐based pre‐treatments. This work evaluates the behaviour of cerium as corrosion inhibitor in methacrylate silane‐based hybrid films containing SiO₂ nano‐particles on AA2024. Hybrid films were deposited on aluminium alloy AA2024 by means of dip‐coating technique. Two different types of coating were applied: a non‐inhibited film consisting of two layers (non‐inhibited system) and a similar film doped with cerium nitrate in an intermediate layer (inhibited system). The film thickness was 5 µm for the non‐inhibited system and 8 µm for the inhibited system. Film morphology and composition were investigated by means of GDOES (glow discharge optical emission spectroscopy). Moreover, GDOES qualitative composition profiles were recorded in order to investigate Ce content in the hybrid films as a function of immersion time in 0.05 M NaCl solution. The electrochemical behaviour of the hybrid films was studied in the same electrolyte by means of EIS technique (electrochemical impedance spectroscopy). Electrochemical measurements provide evidence that the inhibited system containing cerium displays recovery of electrochemical properties. This behaviour is not observed for the non‐inhibited coating. GDOES measurements provide evidence that the behaviour of inhibited system can be related to migration of Ce species to the substrate/coating interface. Copyright © 2010 John Wiley & Sons, Ltd.     

Microstructure Investigation of (Y,Ce)-TZP-Al_2O_3 Composite Materials

The microstructure of selected specimens in the (Y,Ce)-TZP-Al2O3 composite systems was studied. The investigation techniques used in this work included X-ray diffractometry ( XRD ) , Scanning Electroscope ( SEM ) , Transmission Electroscope (TEM), X-ray Energy Dispersion Analysis(EDAX) and High Resolution Electron Microscopy (HREM). Based on the experimental results, the relationship between microstructure and mechanical properties of the specimens was discussed.     

Comparative investigations of structure and properties of BCN coatings deposited by thermal and plasma-enhanced CVD

Hard BCN films were deposited by chemical vapour deposition (CVD) on Si(100) substrates. TCVD (thermal activated) and PECVD (GD or RF microwave plasma-activated, respectively) were used. The films were analysed with respect to chemical state, composition, morphology and microstructure, oxidation behaviour and hardness. Wavelength dispersive X-ray spectroscopy (EPMA), infrared spectroscopy (IR), transmission electron microscopy (TEM), differential thermal analysis (DTA) and hardness evaluation were employed for film characterization. A correlation between deposition parameters and film composition, structure and hardness could be proved in every CVD process. Parallels between TCVD and PECVD films emerged in the case of chemical composition and the correlation between carbon content and hardness values. Considerable differences exist with regard to the microstructure, especially the texture of the films. Moreover in TCVD films the carbon is preferentially incorporated between the BN basal planes, whereas in PECVD films it is incorporated preferentially in as well as between the BN basal planes.     

Synthesis and characterization of conjugated polymers and their blends for optoelectronic applications

Various polymeric blends of hole transporting materials, (such as MEH-PPV and P3HT) and electron transporting materials (such as poly(phenyl-vinyl-quinoline) and poly[2-(4-methacryloxyphenyl)-5-phenyl)-1,3,4-oxadiazole]) have been prepared and investigated. Moreover a soluble, main chain oxadiazole bearing polyether has been synthesized, aiming towards an efficient electron transporting polymeric material which was also used for blend preparation together with P3HT. A deeper investigation into their spectroscopic characteristics using, primarily, FT-IR spectroscopy, but also UV-Vis spectroscopy has been conducted. The surface morphology of these blends was investigated using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) in an attempt to gather information for their solid state properties and morphologies. Finally, DSC measurements provided additional insight into the thermal behaviour of these materials.     

Interpretation of micromechanical measurements on butyl acrylate,vinyl acetate based systems: Role of interfaces in “polymer-polymer composites”

Films were obtained by coalescence of different types of latex particles; the purpose of this work was to get informations on the geometric arrangement (so called “morphology”) of the different phases and on the role of interfaces. Such informations are difficult to get by direct investigations (weak contrast in Transmission Electron Microscopy, poor information provided by X-ray measurements on amorphous polymers …) the analysis of experimental data obtained in high resolution mechanical spectrometry appears powerful: it is possible, for instance, to estimate the profile gradient of composition at the interface. Comparison is made between the morphology of the different phases in some films and the correspondent structure of particles.     

Nickel- and copper-containing oxide films on titanium

We have studied the composition and structure of films 20–30 μm thick prepared by plasmaassisted electrochemical oxidation (PEO) and additionally modified by impregnation in aqueous solutions of nickel and copper nitrates and then annealed. The investigative tools used were powder X-ray diffraction, electron probe microanalysis (EPMA), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy. Unmodified film/titanium composites have a certain catalytic activity in CO oxidation to CO₂ at temperatures above 300°C; for modified layers, these temperatures are noticeably higher. Modification influences the surface structure, relief, and elemental composition. Relations between the composition and catalytic properties of the oxide layers are discussed.     

Chemical Characterization of Airborne Particles in St. Martinus Cathedral in Weert, The Netherlands

Electron probe X-ray microanalysis (EPMA) of single particles and energy dispersive X-ray fluorescence analysis (EDXRF) were applied to determine the chemical composition, size and probable origin of the suspended particulate matter. The aim of the performed research was to determine the chemical composition, size and abundance of aerosol particles responsible for blackening and soiling of the works of art displayed within the Cathedral of Weert in the Netherlands and to verify the possible sources responsible for these processes.     

Photocatalytic properties of Ru-doped titania prepared by homogeneous hydrolysis

Nanocrystalline titania particles doped with ruthenium oxide have been prepared by the homogenous hydrolysis of TiOSO₄ in aqueous solutions in the presence of urea. The synthesized particles were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), Selected Area Electron Diffraction (SAED) and Nitrogen adsorption-desorption was used for surface area (BET) and porosity determination (BJH). The photocatalytic activity of the Ru-doped titania samples were determined by photocatalytic decomposition of Orange II dye in an aqueous slurry during irradiation at 365 nm and 400 nm wavelengths.      

Dynamic mechanical spectrometry for the study of multiphase polymer materials

The dynamic mechanical behaviour of multiphase polymer materials depends on two factors: (i) properties of each phase and (ii) geometric arrangement of these phases (so-called morphology). Analysis of experimental results has been performed in order to separate these two factors; it leads to informations about morphology, presence of interphase between main phases, chemical composition of different domains and possible changes in physical properties of one phase, induced by its neighbours. The interest in such an analysis based on mechanical spectrometry appears important because of difficulties in direct investigations (low contrast in Electron Microscopy, poor information provided by X-ray measurements on amorphous polymers … )     

Investigations on silver/polyaniline electrodes for electrochemical supercapacitors

Polyaniline (PANI) and silver doped polyaniline (Ag/PANI) thin films were deposited on stainless steel substrates by a dip coating technique. To study the effect of doping concentration of Ag on the specific capacitance of PANI the concentration of Ag was varied from 0.3 to 1.2 weight percent. Fourier transform-infrared and Fourier transform-Raman spectroscopy, and energy dispersion X-ray techniques were used for the phase identification and determination of the doping content in the PANI films, respectively. The surface morphology of the films was examined by Field Emission Scanning Electron Microscopy, which revealed a nanofiber like structure for PANI and nanofibers with bright spots of Ag particles for the Ag/PANI films. There was decrease in the room temperature electrical resistivity of the Ag/PANI films of the order of 10(2) with increasing Ag concentration. The supercapacitive behavior of the electrodes was tested in a three electrode system using 1.0 M H(2)SO(4) electrolyte. The specific capacitance increased from 285 F g(-1) (for PANI) to 512 F g(-1) for Ag/PANI at 0.9 weight percent doping of Ag, owing to the synergic effect of PANI and silver nanoparticles. This work demonstrates a simple strategy of improving the specific capacitance of polymer electrodes and may also be easily adopted for other dopants.     

New procedure towards well-dispersed nickel oxide nanoparticles of controlled size

The synthesis of well-dispersed composite Ni/NiO nanoparticles of controlled size has been achieved in organic solution in the presence of polyvinylpyrrolidone, using biscycloocta-1,5-diene nickel as a precursor, upon controlling the water and dioxygen content of the reacting medium. The particles are characterised by magnetisation measurements, Transmission Electron Microscopy and Wide Angle X-ray Scattering. The oxidation of these particles into NiO nanoparticles can be achieved in mild conditions and preserves their dispersion in the polymer matrix.     

Tailoring materials by high-energy ball milling: TiO2 mixtures for catalyst support application

We carried out a rational design of catalyst supports by high-energy ball milling. Tailored mixtures of TiO₂ crystalline phases were obtained using rotational speed and milling time as variable parameters. Polymorphic transformation from anatase to rutile through high-pressure TiO₂ (II) as intermediate was confirmed by X-ray Diffraction (XRD), Raman Spectroscopy and Transmission Electron Microscopy (TEM). Also, starting material doubled its specific surface area due to particle fragmentation, as confirmed by surface area of Brunauer-Emmet-Teller (S_BET) and Scanning Electron Microscopy (SEM). Defects introduced during milling process generated oxygen vacancies in the surface and bulk of supports, as evidenced by X-ray Photoelectron Spectroscopy (XPS) and Electron Paramagnetic Resonance (EPR). Furthermore, longer milling time increased reducibility and oxygen mobility of supports, as observed by H₂ Temperature Programmed Reduction (H₂-TPR) and O₂ Temperature Programmed Desorption (O₂-TPD). Phase composition remained unchanged even under extreme conditions, highlighting the stability of unusual TiO₂ (II) phase. Properties achieved in present materials could benefit metal-support interactions and play a major role in supported catalysts.     

单斜层状LiMnO2的球磨-离子交换法合成及其电化学性能研究

通过球磨促进固相反应法合成出了具有单斜层状结构的前驱物NaMnO₂，随后通过离子交换得到了单斜层状LiMnO₂。XRD测试结果显示产物为单相。扫描电镜(SEM)和透射电镜(TEM)观测结果显示LiMnO₂的粒子尺寸为300～500 nm，HRTEM分析显示干扰条纹的间距为0.485 nm，基本对应于m-LiMnO₂的(001)晶面间距。红外吸收光谱(IR)和X射线光电子能谱(XPS)被用来测量m-LiMnO₂中Mn-O键的伸缩和弯曲振动吸收和Mn元素的价态。合成的m-LiMnO₂在电化学充放电循环初期表现了较好的电化学性能，但其循环寿命仍需要进一步改善。     

Quantitative Sputter Depth Profiling of Silicon- and Aluminium Oxynitride Films

 Silicon- and aluminium oxynitride films have gained attention because of their interesting properties in various fields of technology. The specific properties strongly depend on the concentration of oxygen and nitrogen in the films. For the quantitative analysis of homogeneous silicon- and aluminium oxynitride films, EPMA has been proven a very reliable and precise method of analysis. In order to characterise films with graded composition or interface effects between the film and the substrate it is necessary to use sputter depth profiling techniques such as SIMS, hf-SNMS, AES, or hf-GD-OES. Unfortunately, stoichiometric silicon- and aluminium oxynitride films are insulating and therefore charge compensation has to be applied. For the quantification it was necessary to prepare calibration samples which have been analysed by different bulk analytical techniques such as NRA, RBS and EPMA. With these calibration samples, sensitivity factors have been determined and the functional dependence of the sensitivity factors on the composition has been derived. The advantages and disadvantages of the different sputtering techniques and the applicability of the obtained sensitivity functions for the quantitative depth profiling of silicon- and aluminium oxynitride films are discussed.     

The Low Temperature Processing of Titanium Dioxide Films by the Addition of Trimesic Acid

Sol-gel deposited titanium dioxide films are used for a wide range of applications. One of the drawbacks to these films is that they must be heated in excess of 400^∘C in order to obtain durability. We have found that the processing temperature required to prepare sol-gel derived titanium dioxide films can be significantly reduced by the addition of small amounts of trimesic acid. The addition of this material provides a low energy pathway for the growth of titanium dioxide particles. Titanium dioxide films prepared with trimesic acid show significantly enhanced physical properties with respect to cracking and peeling. Scanning Electron Microscopy and X-Ray Diffraction analyses of films are presented.     

Structural and redox properties of VOx and Pd/VOx thin film model catalysts studied by TEM and SAED

The oxidation of pure V(2)O(3) and Pd/V(2)O(3) films was studied by Transmission Electron Microscopy (TEM) and Selected Area Electron Diffraction (SAED) in the temperature range 673-773 K. Thin films of V(2)O(3) were prepared by reactive deposition of V metal in 10(-2) Pa O(2) on NaCl(001) cleavage faces. Pd particles were epitaxially grown on NaCl(001) and subsequently embedded in V(2)O(3). Oxidation of both pure V(2)O(3) and Pd/V(2)O(3) at 673 K transforms V(2)O(3) into a platelet-like V(2)O(5) structure. At temperatures T>or= 773 K, a reconstruction of the platelet-like V(2)O(5) structure into an array of oblong and needle-type V(2)O(5) nanocrystals of different size occurs. Subsequent reduction of the so-prepared structures in 1 bar H(2) at 573-673 K results in the formation of the cubic VO phase, whereby the external shape of the original crystals is partially maintained. Upon oxidation at 723 K, Pd is transformed into PdO, but its formation is suppressed in comparison with Pd supported on Al(2)O(3) and occurs only at an about 100 K higher temperature than on Pd/Al(2)O(3). The Pd particles are stabilized against oxidation up to 673 K, PdO decomposes upon reduction in hydrogen between 573 and 673 K.