Influence of polishing time on thermo-oxidation characterization of isothermally aged PMR-15 resin

The effect of polishing time on measured oxidation thickness and elastic modulus of isothermally aged PMR-15 neat resin was investigated. A specimen aged 956 h in ambient air at 288 °C (550 °F) was selected for this study. Thermo-oxidation of the specimen results in a surface oxidation layer with different stiffness and polishing characteristics than the interior of the specimen. The specimen was repolished at consecutive time periods from a quick polishing time to extensive polishing time. A white light interferometer was used as a surface profiler to measure height variations from the specimen edges into the interior of the material. Subsequently, optical microscopy and nanoindentation experiments were conducted to correlate observations of oxidation thickness and elastic modulus measurements with polishing time. The modulus profiles obtained from nanoindentation experiments indicate formation of an outer brittle layer followed by a sharp drop in the transition region to the unoxidized interior. The oxidized material is polished at a greater rate than the unoxidized material. The maximum variation in the surface profile from polishing was limited to 5 μm across the oxidation layer (∼150 μm), which results in a slope of ∼2° over the oxidized region. Optical measurements of thickness of oxidized layer and transition region are in good agreement with the height and modulus profiles obtained using the interferometer and nanoindenter, respectively. Results from three techniques show that the measured oxidation thickness and elastic modulus are relatively independent of the polishing time.     

高强度凝胶树脂的合成及其在电厂凝结水精处理系统中的应用

介绍了采用一次聚合工艺合成适用于电厂凝结水精处理混床的凝胶型强酸、强碱离子交换树脂的过程,对树脂的抗渗透冲击强度、氧化稳定性等进行了对比测试,并就该树脂与普通树脂相比较的差异进行阐述。     

Preparation and characterization of graphite-coated metallic electrodes: the graphite-sprayed electrode

Graphite-coated metal electrodes were constructed and evaluated for use in voltammetry. Aluminium, copper and platinum electrodes were sprayed with a colloidal solution of graphite particles dispersed in methyl methacrylate polymer. The polishing step was omitted for anodic stripping voltammetry with a mercury film. The resistance is about 1 Ω. Electrode areas are readily reproduced by utilizing metal supports with equal areas. Background currents are very low and useful potential ranges are extended, with −1.3 to +1.7 V vs. SCE being possible, depending on the electrolyte. It is possible to achieve ±0.1% precision for the peak-currents in the electrochemical oxidation of ferrocyanide. For phenol, which is strongly adsorbed, a precision of 2.5% can be achieved by polishing the electrode before each determination.     

Influence of surface treatments in the initial stages of anodizing Al–Ag alloys in neutral electrolytes

Using voltage-time responses and cyclic voltammetry, the initial stages of anodizing of Al–2.1 at.% Ag and Al–4 at.% Ag alloys are shown to depend upon the heat treatment of the alloys and the pre-treatment of the alloy surfaces. Chemical polishing of solution-treated alloys leads to relatively uniform anodic oxidation on a relatively smooth alloy surface, in the absence of significant effects of coarse, silver-rich intermetallics. In contrast, losses of current to oxygen generation arise for the roughened alloy surface from mechanical polishing. With ageing, secondary reactions at the relatively silver-rich intermetallics are more prevalent, although the effects on the voltage-time response depend upon the balance between processes occurring on the matrix and intermetallic regions, including film growth, oxygen generation within the anodic film, film damage due to release of oxygen, dissolution of silver species and re-growth of damaged film.     

Aerosol-assisted synthesis of monodisperse single-crystalline α-cristobalite nanospheres

Monodisperse single-crystalline α-cristobalite nanospheres have been synthesized by hydrocarbon-pyrolysis-induced carbon deposition on amorphous silica aerosol nanoparticles, devitrification of the coated silica at high temperature, and subsequent carbon removal by oxidation. The nanosphere size can be well controlled by tuning the size of the colloidal silica precursor. Uniform, high-purity nanocrystalline α-cristobalite is important for catalysis, nanocomposites, advanced polishing, and understanding silica nanotoxicology.     

Evaluation of Polyphenols in Wine by Voltammetric Techniques with Screen Printed Carbon Electrodes

The electrochemical oxidation processes that occur during a voltammetric assay in wine samples lead to the formation of species that obstructs the surface and reduce their active area. This effect is critical for screen printed carbon electrodes (SPCE) and leads to abnormal low values of the total polyphenols content of wines, ca. 72 % lower than those obtained with glassy carbon electrodes. This effect was examined using 10 red and Port wine samples. Mechanical polishing and electrochemical‐based treatments for the removal of this fouling layer were tested. The best results were obtained by electrochemical activation in at a constant potential of 1.2 V during 100 s Na₂CO₃ saturated solution, and by polishing. The success of some of these treatments brings an added value to SPCE, as it opens the possibility of their reuse in the wine analysis. This outcome is particularly relevant for quality control where a huge number of analysis is performed and the reduction of cost may dictates the choice of the analytical method.     

镍-磷-锌盐纳米复合化学镀层抗腐蚀性能的研究

镍-磷-锌盐纳米复合化学镀层抗腐蚀性能的研究     

The reactivity of photogenerated NO32− on polycrystalline gold electrodes with different surface structures

We considered the role of the superficial atomic structure of polycrystalline gold electrodes on the electrochemical oxidation and the reduction of NO₃^2? photogenerated by trapping of electrons emitted from the electrode. The perturbation of the superficial structure of the electrode by mechanical polishing slows down the oxidation of NO₃^2?. We observed only an activated process in this case. The superficial atomic reorganization of the surface by cyclic polarization makes this reaction faster without perturbation of the short-range diffusion process of reactive species. The production of highly dispersed surfaces (black gold) gives slightly more active electrodes than the preceding one, but influences the short-distance diffusion mode in solution. The last two electrode types exhibit barrier-less and activated processes for the charge-transfer step.     

稀土抛光粉的生产及应用

综述了稀土抛光粉的各种制造工艺及其在玻璃抛光领域的应用现状，以稀土抛光粉不同的化学成分，粒度，用途等对稀土抛光粉进行了归纳分类，介绍了国内外稀土抛光粉生产企业的产生规律，产品特点，对国内外稀土抛光粉的制备工艺流程进行了归纳，阐述了稀土抛光粉的抛光工艺及抛光机理，重点讨论了稀土抛光粉的应用领域，预测了稀土抛光粉市场的未来，对稀土抛光粉的应用进行了展望。     

计算机硬盘基片CMP中表面膜特性的分析研究

目前,普遍采用化学机械抛光(Chemical-mechanical polishing,CMP)技术对计算机硬盘基片(盘片)表面进行原子级平整。CMP加工中,盘片表面膜及其特性对CMP过程及CMP性能具有关键作用。本文分别采用俄歇能谱(AES)、X射线光电子能谱(XPS)、扫描电镜(SEM)、纳米硬度计、电化学极化法等分析手段对盘片表面物理、化学及机械特性进行了研究,发现盘片CMP后表面发生了氧化,氧化膜在盘片的表层,厚度在纳米量级,氧化产物为Ni(OH)₂;氧化膜为较软的、疏松的、粗糙的多孔结构;氧化膜的存在加快了盘片表面的腐蚀磨损。结合盘片CMP试验结果,推测盘片的CMP机理为盘片表面氧化生成机械强度较低的Ni(OH)₂氧化膜及随后氧化膜的机械和化学去除,二者的不断循环实现表面的全局平面化。     

Voltammetric oxidation of pharmaceutical organic compounds at a new modified electrode: The aluminum graphite spray-covered electrode

A new graphite spray-modified aluminum electrode has been used to determine clozapine, clothiapine, and loxapine in acetate buffer at pH 4.7 and 20% methanol, down to 5 × 10⁻⁶ M concentrations using differential pulse voltammetry. Reproducibility exceeds that of other solid electrodes, being in the range of 1 to 2%. The electrochemical oxidation products of the latter two compounds are strongly adsorbed, causing diminished electrode response, but response is readily restored by polishing of the sprayed electrode.     

Etchant solutions for the removal of Cu(0) in a supercritical CO2-based "dry" chemical mechanical planarization process for device fabrication

The microelectronics industry is focused on increasing chip complexity, improving the density of electron carriers, and decreasing the dimensions of the interconnects into the sub-0.25 mum regime while maintaining high aspect ratios. Water-based chemical mechanical planarization or polishing (CMP) faces several technical and environmental challenges. Condensed CO2 has significant potential for replacing current CMP solvents as a "dry" etching medium because of its unique properties. In working toward a condensed CO2-based CMP process, we have successfully investigated the oxidation and chelation of solid copper metal in liquid and supercritical CO2 using ethyl peroxydicarbonate and a beta-diketone chelating agent.     

紫铜化学抛光的电化学研究

测定了化学抛光过程中紫铜的表面光反射率、失重、表面形貌和电位随时间的变化以及抛光过程的电流－电位曲线。结果表明,紫铜的化学抛光过程由浸蚀,光亮和过腐蚀三个阶段组成。电抛光的钝化膜理论也同样适用于紫铜的化学抛光．     

Simultaneous determination of levodopa and carbidopa by a novel nanostructure modified carbon paste electrode

The electrochemical behavior of levodopa (LD) was investigated on the surface of a carbon paste electrode modified with TiO₂ nanoparticles and 2,2??-(1,2 butanediylbis(nitriloethylidyne))-bis-hydroquinone (BNH). The prepared modified electrode showed an efficient catalytic role in the electrochemical oxidation of LD, leading to a remarkable decrease in oxidation overpotential and enhancement of the kinetics of the electrode reaction. The mechanism of the electrocatalytic process on the surface of the modified electrode was analyzed by obtaining the cyclic voltammograms in various potential sweep rates. This modified electrode exhibited well-separated oxidation peaks for LD and carbidopa (CD). The differential pulse voltammetry was applied as a very sensitive analytical method for the determination of LD and CD. A linear dynamic range of 2.0?C600.0 and 20.0?C400.0???M with a detection limit of 0.2???M (with sensitivity of 0.199 ??A ??M^?1) and 10???M (with sensitivity of 0.024???A???M^?1) was obtained for LD and CD, respectively. The modified electrode was prepared quite easily and renewed on the surface by simple polishing.     

The influence of initial surface conditions on field crystallization of anodic aluminum oxide films determined by synchrotron X‐ray diffraction

X‐ray diffraction measurements were performed using synchrotron radiation at the SPring‐8 facility and electrochemical techniques to investigate the effect of polishing methods and storage conditions on the crystal structure of air‐formed oxide films and anodic oxide films formed on highly pure aluminum. Storage in an N₂ environment hinders local film breakdown during anodizing, and it was established that the X‐ray diffraction measurements showed the presence of a γ‐Al₂O₃ in the anodic oxide film formed on mechanically polished (MP) specimens. Formation of γ‐Al₂O₃ during anodizing was inhibited by electropolishing because of the removal of the work‐hardened layer that was formed on the MP by electro‐polishing. The X‐ray diffraction results do not show clear differences in the influence of the polishing method on the crystal structure of air formed oxide film. This is due to the very fast oxidation rate of the air‐formed oxide film and very long storage times for the X‐ray measurements. The anodic oxide film formed on aluminum, which has a very flat surface, shows color and the color depended on grain orientation. The electrochemical impedance of the MP specimen is slightly lower than that of the mechanically and then electrochemically polished specimen at the middle frequency range. This impedance difference may be due to formation of γ‐Al₂O₃ in the amorphous anodic oxide film and the thickness of the film. Copyright © 2010 John Wiley & Sons, Ltd.     

铜在甲胺介质铁氰化钾化学-机械抛光液中的电化学行为

二甲氧基苯胺;铜在甲胺介质铁氰化钾化学-机械抛光液中的电化学行为     

A concomitant use of some radioanalytical and metallurgical methods: Application to the study of the thermal oxidation of titanium

Polycrystalline titanium samples were oxidized in pure oxygen under a 75 torr pressure, at temperatures ranging from 400°C to 500°C, and for times up to 2 hrs. A similar treatment was applied to some single crystal samples, so as to show the relationship between the crystallite orientation and the oxidation rate. The oxide films were studied by means of radioanalytical techniques, such as nuclear microanalysis, electron diffraction and ESCA, in addition to most classical techniques such as optical and electron microscopy. The complementary side of these methods is showed. They permit us to determine the contamination of the metallic surface introduced by the polishing treatments, the oxidation rate at constant temperature, and the structure of the oxides which exists in the films. These ones are especially TiO₂, Ti₃O₅, Ti₂O₃ and TiO.     

纳米金刚石的表面修饰及应用

纳米金刚石是一种新型的碳纳米粒子,具有硬度高、化学稳定、良好的生物相容性和热传导性等优点,有广阔的应用前景。对于纳米金刚石的应用,大多需要对其进行表面修饰。本文主要结合近年来国内外研究成果,阐述了氢化、羧酸化、羟基化及其他表面修饰等纳米金刚石的表面修饰方法,总结了纳米金刚石在润滑、抛光、生物医学、复合材料等领域的应用。     

Electrochemical and spectroscopic characterization of quinone functionalized exfoliated graphite.

Natural graphite was exfoliated by thermal decomposition of graphite-bisulfate intercalation compound. Oxidative/reductive pre-treatment of exfoliated graphite was subsequently carried out to introduce various functional groups on the graphite surface. The resulting material was covalently modified with redox active quinones. The covalent modification was effected through oxygen containing functional groups formed on the graphite surface. The modified exfoliated graphite was characterized by infra-red (FTIR) and X-ray photoelectron spectroscopy (XPS). Electrochemical characterization of the pressed pellets of the modified graphite showed that the modification occurred at the edge sites. These electrodes were found to be very stable and the surface renewal was simply accomplished by polishing the surface using SiC emery sheets. Application of the benzoquinone modified electrode for the electrocatalysis of ascorbic acid oxidation was demonstrated.     

成像级CdSe中红外波片的表面处理工艺研究

本文利用改进的垂直无籽晶气相升华法生长出尺寸达Φ30×40 mm的优质硒化镉(CdSe)单晶体。解理晶体,通过X射线衍射仪测试精确的获得(001)晶面。然后定向切割、研磨、抛光,获得了尺寸为20×20×3mm~3的CdSe中红外波片初胚。以弱碱性溶液与刚玉粉的混合液作为抛光液,利用化学机械抛光法对CdSe中红外波片进行表面抛光处理。结果显示,抛光处理有效的减少了波片表面的损伤层、划痕及结构缺陷,晶片表面的粗糙度降低,在2~20μm波段透过率较高(达到70%),满足中红外波片的应用需求。