A wide variety of anticorrosive treatments for aluminum alloys that can be employed as “green” alternatives to those based
on Cr(VI) are currently under development. This article reports a study of the morphological and anticorrosive characteristics
of surface layers formed on the Al–Cu alloy AA2017 by immersion treatment in baths of cerium salt, accelerated by increased
temperature and the employment of hydrogen peroxide. Scanning electron microscopy (SEM)/X-ray energy dispersive spectroscopy
(XEDS) studies of the samples treated have demonstrated the existence of a heterogeneous layer formed by a film of aluminum
oxide/hydroxide on the matrix, and a series of dispersed islands of cerium over the cathodic intermetallics. The protective
efficacy has been evaluated using electrochemical techniques, linear polarizations (LP) and electrochemical impedance spectroscopy
(EIS), and salt spray tests. The results obtained indicate that the layer provided good resistance to corrosion in media with
chlorides, and the method gives a considerable reduction of the time required for the immersion treatments. 相似文献
A novel methodology is presented and applied to measure the shear interface strength of fiber-reinforced polymers. The strategy is based in fiber push-in tests carried out on the central fiber of highly-packed fiber clusters with hexagonal symmetry, and it is supported by a detailed finite element analysis of the push-in test to account for the influence of hygrothermal residual stresses, fiber constraint and fiber anisotropy on the interface strength. Examples of application are presented to determine the shear interface strength in carbon and glass fiber composites reinforced with either thermoset or thermoplastic matrices. In addition, the influence of the environment (either dry or wet conditions) on the interface strength in C/epoxy composites is demonstrated. 相似文献
This article is the second of a series of three papers concerning monitoring of filament wound cylinders using Bragg gratings.
In this second part, the tooling presented in Part I is used to embed gratings and thermocouples in filament wound glass reinforced
epoxy composite cylinders during fabrication. Bragg grating strain was obtained from wavelength and temperature response,
by a calibration technique described here. Results from tests on five cylinders show the Bragg grating’s capability to monitor
strain evolution during fabrication, and the capacity to detect several phenomena occurring during cure is established, in
addition to quantifying the initial material condition of the cylinder before it enters service. 相似文献
The range of theoretical frameworks currently being used by researchers into information behaviour is abundant and diverse. We need to examine thoroughly the contribution of theories and models to further research, as this would help to improve future investigations in the field. This paper adopts this approach, by thoroughly examining the influence that Elfreda Chatman’s three middle-range theories have had on subsequent research. A citation context analysis was carried out on the basis of those received by Information poverty theory, life in the round theory and normative behaviour theory. Analysis covered the year of publication, the type of work and the subject-matter of the citing documents. The cites in context or theoretical incidents were analysed for frequency of citation in citing documents, the content of Chatman’s work being cited, the context co-citation analysis, the citation style and the citation location. The analysis of citation in context has allowed us to draw a distinction between the author and her work, while verifying that not all cites are the same. These differences reflect the unequal relevance of these theories to subsequent research.