Off-Optimum Cure of Aerospace Epoxy Adhesives

Four epoxy film adhesives used in aircraft manufacture and repair have been examined to establish the effect of deviation from the cure cycle specified by the manufacturer. In addition to the variation of the cure cycle, two surface preparations of the aluminium adherends (chromic acid etch or grit blast followed by silane treatment) were evaluated. Thermal analysis was used to examine the cure envelope of the adhesive, and its extent of cure and glass transition temperature. The adhesive properties were assessed by shear strength (in both single lap joints and in Iosipescu configuration), durability (Boeing wedge test) and chemical resistance to selected aggressive fluids. The sensitivity of the performance of a particular adhesive to offoptimum cure conditions depends on its composition and needs to be determined, not predicted.     

Asymmetric alumina membranes electrochemically formed in oxalic acid solution

Alumina membranes were fabricated by anodizing aluminium metal in 0.15 M oxalic acid. The growth kinetics of the porous layer were investigated in the temperature range –1 to 16 °C using linear potential scans up to 70 V. The faradaic efficiencies of metal oxidation and of porous layer formation, determined by applying Faraday's law, were found to be independent of both temperature and electrical charge. SEM analysis of the metal-side and solution-side surfaces revealed different morphologies. After dissolution of the barrier layer in phosphoric acid, the metal-side surface showed circular pores whose size of about 90 nm was found to be uniform and independent of temperature. The pore population was also practically independent of temperature and a value of about 4 × 10¹³ pores m^–2 was determined. On the solution-side surface the presence of a deposit partially occluding the mouths of pores was observed. This coating could be removed by chemical etching in NaOH or thermal treatment at 870 °C, where decomposition of oxalate occurs. This supports the hypothesis that the deposit consists of an aluminium salt containing oxalate anions precipitated from the solution. The results show that it is possible to control the morphological characteristics of the anodic alumina membranes by careful choice of experimental conditions.     

超高纯铜的制备方法和应用

简要介绍了超高纯铜(UHPC)的几种精炼方法，以及它在工业方面的应用。并对超高纯铜的研究开发趋势及应用前景进行了展望。     

喷气纺的条子制备

新纺纱系统的研制开发与传统纺纱工艺的进一步发展都需要对技术要求和经济效果进行反复准确的分析。由于喷气纺的推广，尤其是在美国的推广使用，Rieter公司对此工艺的原材料的最佳准备状态进行了研究。本文即为Rieter公司纺织技术专家所完成的这方面大量研究工作的一个概述。     

阳离子型聚丙烯酰胺絮凝剂的开发与应用

阳离子型聚丙烯酰胺具有许多优点，极具开发研究价值，是重要的高分子絮凝剂。介绍了阳离子型聚丙烯酰胺絮凝剂的制备方法，应用及其絮凝作用机理，并分析了其发展方向。     

胶体五氧化二锑研究现状及发展方向

对胶体五乳化二锑的研究现状进行了回顾，详细概述了胶体五乳化二锑的各种制备方法及其特点和适用范围，讨论了两种成胶理论。针对目前存在的问题，对胶体五乳化二锑的研究方向及研究重点提出了几点建议。     

Preparation of flat-polished specimens for SEM-backscattered electron imaging and X-ray microanalysis—importance of epoxy impregnation

Representative and quantitative microstructural information of cement-based materials can be obtained in the backscattered electron and X-ray modes of the scanning electron microscope (SEM). One prerequisite, of several, is to use flat specimens. Microstructures that are minimally affected by the grinding and polishing necessary to produce the flat surface can be obtained. It is essential to fill the pores of the specimen with epoxy resin prior to grinding and polishing. After hardening, the epoxy stabilizes the microstructure and enables it to withstand the stresses of grinding and polishing without alteration. In the present paper, we describe a preparation technique that we consider to have produced excellent polished specimens. The importance of epoxy impregnation is demonstrated.     

A strategy for integrating product conceptualization and bid preparation

Collaboration with other members of the supply chain is one means by which small and medium sized enterprises (SMEs) can compete in today’s global business environment. Thus, early stages of the new product development process involve both technical activities, e.g., product platform definition, and commercial activities, e.g., bidding for contracts. This paper introduces an integrated collaborative bidding and design system (CBDS) to help SMEs coordinate the two aspects. General sorting was employed for initial requirements acquisition and platform definition; while a self-organizing map (SOM) neural network was combined with a concurrent cost-schedule estimation strategy for refinement of design options and bid evaluation/preparation. A case study on cellular phone design was then applied for illustrating the proposed prototype system.     

AP的安全制备（英）

1 IntroductionThe ammonium perchlorate ( AP)-based compositepropellant is currently the most widely used one becausethis propellant has good burning characteristics and me-chanical properties. One of the few serious drawbacks ofthe AP-based propellant is that its products of combus-tion, which include HCl, chlorine, and chlorine oxides,cause atmospheric pollution. Increasing concern for aclean atmosphere in recent years has resulted in a com-pelling need for developing a chlorine-free,enviro…     

Dental amalgam – the effect of the technology of alloy powder preparation on the corrosion behaviour and the release of mercury

Dental amalgams are based on a broad spectrum of materials differing in their chemical composition, metallurgical treatment, and in the way the initial alloys powders are prepared. In addition to their chemical composition, amalgams based on various powders differ in both their microstructure and the amount of mercury needed for preparation. All these facts may affect electrochemical processes occurring during their interaction with oral fluids, and also mercury release. While verifying the effect of the technology used for the preparation of the high‐copper ternary alloy powder on the properties of resulting amalgams, this study aimed at the mechanism of their interaction with a model saliva solution as well as mercury release was included. Measurements were done in a model saliva solution using standard electrochemical methods and exposition measurements. The interaction of individual types of amalgams with artificial saliva did not reveal any significant differences. The free corrosion potential of all these amalgams in an aerated solution settled in the range of values in which tin oxidation, resulting in a layer of insoluble corrosion producsts, turned out to be the dominant anodic process. The rate of mercury release was the lowest for amalgams based on a gas‐atomized alloy. The highest rate of mercury release, and also its dependence on time, was exhibited by lathe‐cut powder based amalgam. In addition to different volume fraction of the Ag‐Hg phase and the level of its tin alloying, this different behaviour may be explained by differences in the rate at which a layer of tin corrosion products acting as a barrier to mercury release is formed.