Role of Nickel Dip in Enameling of Sheet Steel

An investigation was made of the effects of (a) the firing time and (b) the weight of nickel deposited from the nickel-dip solution on the adherence developed by a cobalt-free and a cobalt-bearing ground-coat enamel on both enameling iron and a titanium-bearing low-carbon steel. At 1550°F. the nickel improved the measured adherence index the most during the 2-minute firing. The effect of the nickel, however, decreased markedly with longer firing times. There was an optimum nickel deposit for maximum adherence, an optimum that varied from 50 to about 120 mg. per sq. ft., depending on the type of cleaning used and on the type of enamel applied. The nickel dip reduced the tendency to fish-scale. Furthermore, there was an apparent relation between fish-scaling resistance and good adherence; no specimen with an adherence index of 70 or above showed fish-scaling tendencies. Metallographic studies of the interface of coated specimens showed that nickel dipping of the steel before enameling brought about a surface roughening during the firing operation. A relationship was noted between the degree of roughening and the measured adherence index. The roughening of the steel surface was ascribed to galvanic corrosion.     

In-Situ Measurement of Chloride Ion at the Coating/Metal Interface

One of the main reasons for the lack of a complete understanding of corrosion and adhesion failures of a coated metal is the lack of analytical instrumentation to probe the behaviors of corrosive agents at the coating/metal interface. We have developed a procedure based on microelectrodes for studying in situ the behavior of chloride ions at a coating/metal interface. The procedure requires an attachment of a double-barreled Cl^? ion-selective microelectrode at the coating/metal interface, thus allowing direct measurements of Cl^? concentration changes at localized areas under a coating. The procedure provided very useful information for mechanistic studies of corrosion under coatings, as well as for transport studies of Cl^? ions through a coating. The procedure should also be useful for studying the roles of Cl^? in localized corrosion.     

In-Situ Measurement of Chloride Ion at the Coating/Metal Interface

One of the main reasons for the lack of a complete understanding of corrosion and adhesion failures of a coated metal is the lack of analytical instrumentation to probe the behaviors of corrosive agents at the coating/metal interface. We have developed a procedure based on microelectrodes for studying in situ the behavior of chloride ions at a coating/metal interface. The procedure requires an attachment of a double-barreled Cl^- ion-selective microelectrode at the coating/metal interface, thus allowing direct measurements of Cl^- concentration changes at localized areas under a coating. The procedure provided very useful information for mechanistic studies of corrosion under coatings, as well as for transport studies of Cl^- ions through a coating. The procedure should also be useful for studying the roles of Cl^- in localized corrosion.     

Investigation of Processes Occurring at the Metal/Polymer Coating/Electrolyte Interface

The methodical approach and the cell to study electrochemical processes occurring during cathodic disbondment of a polymer coating are worked out. They permit one to investigate the role of each process separately when supervising the metal substrate potential, electrolyte and polymer coating composition at a metal/polymer/electrolyte interface. The cathodic disbondment of ethylene-vinyl acetate copolymer, polyisoprene and poly(vinyl chloride) coatings are studied. It is found that the cathodic disbondment rate for ethylene-vinyl acetate copolymer coatings depends on double layer parameters at the interface. These parameters are determined by specific volume charge of hydrated cations of the electrolyte, potential of the substrate, the presence of oxygen, surface active substances, etc. Based on the data of IR spectroscopy in internal reflection applied to disbonded films, it is established that during the cathodic disbondment an electron transfer to polymer functional groups, as well as an attacking of the adhesion bonds by active intermediates of oxygen reduction, occurs resulting in an electrochemical degradation of the polymer and an adhesion loss. It is shown that the electrochemical transformations at the steel/poly(vinyl chloride) interface can lead to the appearance of new adhesion bonds, increasing adhesion strength and decelerating the cathodic disbondment.     

Observations on Finger-like Crack Growth at a Urethane Acrylate/Glass Interface

Interfacial crack growth behavior along a urethane acrylate/glass interface is characterized by the development of finger-like perturbations along the advancing crack front. The finger-like perturbations grow from a slightly irregular crack front until they reach a steady-state where the velocity of the finger tips equals the velocity of the finger valleys. Once the fingers reached steady-state, the crack velocity was dependent on the applied strain energy release rate via a power law relationship where the exponent was independent of test humidity; however, the multiplicative constant A decreased by an order of magnitude from 80 to 15% RH. The spacing of the fingers was found to be independent of the crack's velocity and the relative humidity of the environment.     

Observations on Finger-like Crack Growth at a Urethane Acrylate/Glass Interface

Interfacial crack growth behavior along a urethane acrylate/glass interface is characterized by the development of finger-like perturbations along the advancing crack front. The finger-like perturbations grow from a slightly irregular crack front until they reach a steady-state where the velocity of the finger tips equals the velocity of the finger valleys. Once the fingers reached steady-state, the crack velocity was dependent on the applied strain energy release rate via a power law relationship where the exponent was independent of test humidity; however, the multiplicative constant A decreased by an order of magnitude from 80 to 15% RH. The spacing of the fingers was found to be independent of the crack′s velocity and the relative humidity of the environment.     

Effect of the Molecular Length of n-Alkylsilanes on the Adhesion at a Rubber/Glass Interface

The effect on the peeling energy, G, of glass/styrene-butadiene rubber (SBR) assemblies of the length, N, of the alkyl chain, ranging from 4 to 30 carbon atoms, of silane coupling agents is determined. Experimentally, it is shown that G strongly increases with N. Therefore, considering that the rheological model of adhesion (or model of multiplying factors) is valid, G is assumed equal to the product of three terms: the reversible adhesion energy, W. at the interface, the viscoelastic dissipation factor, φ, of SBR and a “molecular factor” to be determined. Finally, it appears that this latter factor depends linearly on N. Such a result should be consistent with an extraction (“suction”) process of the silane alkyl links from bulk SBR during peeling experiments.     

Effect of the Molecular Length of n-Alkylsilanes on the Adhesion at a Rubber/Glass Interface

The effect on the peeling energy, G, of glass/styrene-butadiene rubber (SBR) assemblies of the length, N, of the alkyl chain, ranging from 4 to 30 carbon atoms, of silane coupling agents is determined. Experimentally, it is shown that G strongly increases with N. Therefore, considering that the rheological model of adhesion (or model of multiplying factors) is valid, G is assumed equal to the product of three terms: the reversible adhesion energy, W. at the interface, the viscoelastic dissipation factor, φ, of SBR and a “molecular factor” to be determined. Finally, it appears that this latter factor depends linearly on N. Such a result should be consistent with an extraction (“suction”) process of the silane alkyl links from bulk SBR during peeling experiments.     

浮法玻璃工厂DCS系统人机界面设计

基本的设计原则、严格的设计标准以及满足客户需求的设计是浮法玻璃DCS HMI设计不可分割的三个重要组成部分,功能完善的HMI设计应该遵循如上标准.一个制作精良的DCS HMI系统,不仅是使用者和电气系统对话的桥梁,能为工厂安全生产提供保障,也是建立完整的企业视觉形象的手段.它通过良好的操作体验和友好的界面为公司建立品牌形象,形成品牌语言,维护企业的竞争地位,促进企业的成长及发展.     

Effect of Catalyst Preparation on Catalytic Activity: V. Chemical Structures on Nickel/Alumina Catalysts

In situ X-ray photoelectron spectroscopy (XPS or ESCA) was used to identify the nickel species on Ni/Al₂O₃ catalyst surfaces as a function of nickel weight loading. The ESCA results show that the only nickel species on the reduced catalyst surface is NiAl₂O₄ for low weight loading catalysts (< 1 wt.%) whereas both nickel and NiAl₂O₄ are present on high weight loading catalysts. The carbon monoxide temperature-programmed reduction (CO-TPR) results, after reduction of the catalysts in hydrogen, confirm that each type of nickel species acts as a different reaction center for methane production. The high-temperature methane peak observed only from CO-TPR spectra of low weight loading catalysts is due to NiAl₂O₄; a low-temperature peak, which appears as the weight loading is increased, is due to nickel. Steady-state reaction kinetics for methane production yields activation energies that increase with increasing weight loading of the catalyst. The apparent activation energies for catalysts with a single methane peak in their CO-TPR spectra were normally distributed. The apparent activation energies for catalysts with two methane peaks in their CO-TPR spectra were also normally distributed when the method of the catalysts' preparation was considered in testing the statistical nature of the distribution. This study suggests that the spread in the distribution of the apparent activation energies can be related to the structure of the reaction centers on the catalyst surface. The catalysts with a single methane peak in their CO-TPR spectra have uniformly dispersed NiAl₂O₄ species and result in the lowest spread (±0.2 kcal/mol, 0.84 kJ/mol). Catalysts prepared by incipient wetness with two methane peaks in their CO-TPR spectra have more uniform and larger “particle-like” nickel present on the surface than catalysts prepared by wet impregnation; the result is a spread of ±1.0 kcal/mol (4.2 kJ/mol) in the normal distribution in apparent activation energies. Catalysts prepared by wet impregnation have smaller nickel particle sizes and greater heterogeneity in reactive centers; the spread in the distribution of activation energies of catalysts prepared by this method is ±2.6 kcal/mol (10.9 kJ/mol).     

Microalloy Precipitation at the Glass–Steel Interface Enabling Adherence of Porcelain Enamel

The adherence of vitreous enamels on steel plates is studied clarifying the mechanisms taking place at the interface during firing. Evidence is provided from electron microprobe analysis for an iron alloy precipitation at the interface, which results from oversaturation of ferrous iron in the enamel glass. Subsequent coalescence of the alloy particles is observed but only after their bonding to the base metal adherence after cupping is achieved. The formation of microalloys requires Co²⁺, Ni²⁺, and Cu²⁺ ions in the enamel glass. A selective dissolution of the base metal by the latter cations does not occur.     

催化反应与膜分离耦合系统中镍催化剂的使用

在用于对硝基苯酚加氢制备对氨基苯酚的反应-膜分离耦合系统中,催化剂在反应时以悬浮态形式应用,然后用无机陶瓷膜分离回收,催化加氢速率及膜过滤速率是决定该系统运行效率的关键.研究通过综合考察镍粉体催化剂的反应活性与膜分离性能来选择合适的催化剂.实验结果表明,在研究体系中,化学还原法制备的纳米镍粉活性优于物理气相沉积法制备的纳米镍粉和微米镍粉,主要因为化学还原法制备的纳米镍粉具有较大的活性比表面积.膜分离几种镍粉时,活性较高的纳米镍通量较低,而活性较低的微米镍通量较高.通过将具有高活性的纳米镍粉与具有高通量的微米镍粉以适当比例混合使用,不仅可以获得较高的催化活性,同时可以改善膜通量,对反应-膜分离耦合系统的工业化应用具有参考价值.     

The Use of Monochromated XPS to Evaluate Acid-Base Interactions at the PMMA/Oxidised Metal Interface

Recent studies have proposed that a near-interface conformation of PMMA in PMMA/metal substrate systems is different from the bulk polymer. High-resolution XPS analysis using monochromated X-ray sources has shown that PMMA interactions with metal oxide substrates are determined by the acido-basic nature of the substrate. It has also been shown that PMMA interacts with acidic sites on oxidised silicon via the carbonyl oxygen, and strongly basic sties on oxidised copper and nickel will react with the carboxyl carbon via nucleophilic attack. On amphoteric substrates, such as oxidised iron and aluminium, it is proposed that hydrolysis of the methyl ester occurs at weak basic sites to form a carboxylate, resulting in complexes being formed with the metal substrate. Such acid-base interactions would result in the orientation of PMMA at the interface to be dependent on the acido-basic nature of the substrate. This study also shows the resolution of a microfocussed monochromated X-ray source retrofitted to an older XPS spectrometer to be close to that of the Scienta ESCA 300 instrument.     

SiO2-BaO体系玻璃与金属的封接工艺

采用高温固相法制备出SiO2-BaO体系的特种玻璃,并与碳钢、合金等金属封接,制备了SiO2-BaO体系的特种玻璃封接元件.研究了封接温度和时间、封接气氛和退火等工艺参数对封接样品抗压强度、导电性能、密封性和热学稳定性的影响.通过扫描电子显微镜和能谱仪对封接界面处的形貌和元素进行了分析.结果表明:制备的封接器件具有优良的力学性能、密封性、热稳定性及电性能.最佳的封接工艺参数为:封接温度为975～985℃、封接时间为20 min、封接气氛为N2;其退火温度为490～530℃,退火时间为20 min.玻璃和金属封接处致密,无裂缝和气泡缺陷.封接界面处化学组成成分中最多的元素是C、Si、Ba和Mn.     

Evidence for Diffusion of Zerovalent Metal Atoms during Glass/Metal Sealing

Wavelength-dispersive X-ray analysis and X-ray photoelectron spectroscopy were used to determine the presence of zerovalent nickel, chromium, and iron in the glass of a lithia-alumina-silica-based glass/Inconel 718 seal. Evidence for the resultant diffusion of these atoms from the Inconel substrate into the glass network is presented.     

Catalytic Activity of Supported Platinum and Metal Oxide Catalysts for Toluene Oxidation

Oxidation of toluene has been investigated over supported platinum as well as over a variety metal oxide (M _x O _y ) catalysts dispersed on high surface area γ-Al₂O₃. Catalysts were characterized with respect to their specific surface area (BET), metal dispersion (selective chemisorption of CO), phase composition and M _x O _y crystallite size (XRD) and reducibility (H₂-TPR). Catalytic performance for the title reaction was investigated in the temperature range of 100–500 °C, using a feed composition consisting of 0.1% toluene in air. For Pt/M _x O _y catalysts, it has been found that catalytic performance depends on the nature of the support, with Pt/CeO₂ being the most active catalyst at low temperatures. The intrinsic reaction rate per surface platinum atom does not depend on Pt loading (0.5–5 wt%), at least for Pt/Al₂O₃. Reducible metal oxides, such as ceria, are active for the title reaction and catalytic performance is improved significantly with increase of specific surface area (SSA). However, the intrinsic reaction rate per unit surface area is invariant with SSA. Dispersion of M _x O _y on high surface area inert supports, such as Al₂O₃, results in materials with relatively high catalytic activity, which seems to correlate well with the reducibility of metal oxides. Catalytic performance of M _x O _y /Al₂O₃ catalysts can be optimized by proper selection of M _x O _y loading. Best performing catalysts of this series include 60% MnO, 90% CeO₂ and 5% CuO on Al₂O₃ which, under the present experimental conditions, are able to completely convert toluene toward CO₂ at temperatures lower than 350 °C. Dispersion of Pt on M _x O _y /Al₂O₃ catalysts improves significantly the catalytic performance of irreducible M _x O _y but does not alter appreciably the activity of reducible M _x O _y /Al₂O₃ catalysts.     

Catalytic Activity of ZSM-11 Zeolites Modified with Metal Cations for the Ethane Conversion

ZSM-11 zeolite samples differing by their active sites (H⁺ and different metal cations) have been studied in the transformation of ethane into aromatic hydrocarbons. A relationship between Lewis sites increasing–aromatization capacity and possible reaction steps have been suggested.     

Charge and Mass Transfer Across the Metal/Solution Interface

Electrode reactions are characterized by charge transfer across the interface. The charge can be carried by electrons or by ions. It is shown here that when both mass and charge cross the interface, the charge must be carried by the ionic species, not by the electrons, as a result of the very large difference in the time scale for electron and ion transfer. A prime example of charge transfer by ions is metal deposition. It is proposed that ion transfer occurs by migration of the ions across the interface, under the influence of the high electrostatic field in the double layer. The rate constants observed for metal deposition are comparable to those for outer-sphere charge transfer. These unexpectedly high rate constants for metal deposition are explained by a model in which removal of the solvation shell and reduction of the effective charge on the metal ion occur in many small steps, and a make-before-break mechanism exists, which lowers the total Gibbs energy of the system as it moves along the reaction coordinate from the initial to the final state.