The Experts below are selected from a list of 153 Experts worldwide ranked by ideXlab platform
A. Dörner - One of the best experts on this subject based on the ideXlab platform.
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Corrosion studies on aluminium reinforced with uncoated and coated carbon fibres
Composites Science and Technology, 1999Co-Authors: Bernhard Wielage, A. DörnerAbstract:Knowing materials behaviour under conditions of Electrochemical Attack is an important necessity for engineering applications, especially in marine environments. The considerable deterioration of the Electrochemical corrosion resistance which results from the reinforcement of aluminium with carbon fibres demands preventative measures. In order to retain usual life times of applications, suitable corrosion protection has to be implemented. The present study deals with an internal corrosion protection process resulting from the use of suitable fibre coatings, viz. a pyrolytic carbon (pyC) coating and a nickel fibre coating. However, neither the ceramic pyC coating nor the metallic nickel coating effect an improvement of the corrosion resistance in aqueous solutions of 3.5 wt% NaCl or 3.5 wt% Na2SO4. Although, the simple immersion test confirmed the lowest anodic matrix dissolution for metal-matrix composites (MMCs) formerly containing nickel-coated fibres, the polarisation of the MMCs to more positive potentials causes greatly accelerated Electrochemical dissolution. Furthermore, the observed segregation of elemental nickel to the sample surface after the immersion tests in both electrolytes indicate additional susceptibility to galvanic coupling. MMCs reinforced with carbon fibres obtaining a pyrolytic carbon coating show evidence of strongly accelerated Electrochemical corrosion. Because the microstructure and the surface area of the pyrolytic carbon differs from that of the carbon fibres, a probable reason for the enhanced corrosion susceptibility may be the higher reactivity of the pyC coating. This result stresses the importance of taking into account the features of the carbon of the reinforcing component and to distinguish between different carbon types. Special emphasis should be placed on the processing of pyC coatings in order to generate pyC coatings with few active sites and low reactivity.
C. Duret-thual - One of the best experts on this subject based on the ideXlab platform.
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The resistance to localized corrosion in neutral chloride medium of an AISI 304l stainless steel implanted with nitrogen and neon ions
Corrosion Science, 1992Co-Authors: R. Sabot, R. Devaux, A.m. De Becdelievre, C. Duret-thualAbstract:The Electrochemical behaviour of AISI 304 and 304L stainless steels implanted with N+ or Ne+ ions in 0.5 and 0.02 M NaCl solutions is compared. The role of dose and implantation current density are studied. Surface analyses of samples are systematically carried out before and after corrosion tests. The pitting potential of implanted samples are always lower than that of unimplanted ones: the defects generated by the implantation process are probably active sites for pitting. The pit propagation is hindered. The nitrides or a′-martensite layers obtained after elimination of the superficial layers (iron oxide and nickel phase) by Electrochemical Attack of implanted steel in acidic solution play an important role in this process.
Adam Cooney - One of the best experts on this subject based on the ideXlab platform.
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Characterization and Modeling of Bonded Piezoelectric Sensor Performance and Durability in Simulated Aircraft Environments (Preprint)
2006Co-Authors: James L. Blackshire, Steve Martin, Adam CooneyAbstract:Abstract : The performance characteristics of surface-bonded piezoelectric sensors were studied under accelerated exposure conditions typically found in operational aircraft environments. In particular, sensor performance was studied for freeze-thaw, elevated heat levels, Electrochemical Attack, substrate bend and tensile strains, and dynamic vibration conditions. Evidence of both gradual and abrupt sensor performance degradation was experimentally observed due to undesired load transfer processes, which resulted in adverse sensor disbond and cracking events. Models were developed to better understand the critical shear-strain and viscoelastic conditions present in a typical surface-bonded sensor system, which permitted key material parameters related to bond and piezoelectric material type to be identified. Preliminary results will be presented for making improved bonded sensor system design choices based on the long-term exposure conditions expected in typical aircraft flight environments. Future activities are focused on verifying system performance using accelerated environmental testing, with the ultimate goal of improving the durability and survivability of surface-bonded piezoelectric sensor systems in typical aerospace environments.
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Characterization of Bonded Piezoelectric Sensor Performance and Durability in Simulated Aircraft Environments
AIP Conference Proceedings, 2006Co-Authors: James L. Blackshire, Adam CooneyAbstract:Significant progress has recently been reported in the area of integrated structural health monitoring, with many sensor systems being deployed in actual operational environments. A key question that needs to be addressed and answered with regard to successfully implementing structural health monitoring technologies in aerospace systems involves the long‐term operability, durability, and survivability of integrated sensor systems and their associated hardware. In this activity, the performance characteristics of surface‐bonded piezoelectric sensors have been studied under accelerated exposure conditions typically found in an operational aircraft environment. In particular, sensor performance was studied for freeze‐thaw, moderate heat levels, humidity, Electrochemical Attack, substrate bend and tensile strains, and dynamic vibration conditions. The sensor performance was characterized using displacement‐field imaging, pitch‐catch signal transmission, and pulse‐echo signal transmission. Evidence of general ...
Noureddine Gabouze - One of the best experts on this subject based on the ideXlab platform.
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Macropore formation in p-type silicon: toward the modeling of morphology.
Nanoscale Research Letters, 2014Co-Authors: Amel Slimani, Hervé Henry, Mathis Plapp, Abdelhamid Iratni, François Ozanam, Jean-noël Chazalviel, Noureddine GabouzeAbstract:The formation of macropores in silicon during Electrochemical etching processes has attracted much interest. Experimental evidences indicate that charge transport in silicon and in the electrolyte should realistically be taken into account in order to be able to describe the macropore morphology. However, up to now, none of the existing models has the requested degree of sophistication to reach such a goal. Therefore, we have undertaken the development of a mathematical model (phase-field model) to describe the motion and shape of the silicon/electrolyte interface during anodic dissolution. It is formulated in terms of the fundamental expression for the Electrochemical potential and contains terms which describe the process of silicon dissolution during Electrochemical Attack in a hydrofluoric acid (HF) solution. It should allow us to explore the influence of the physical parameters on the etching process and to obtain the spatial profiles across the interface of various quantities of interest, such as the hole concentration, the current density, or the electrostatic potential. As a first step, we find that this model correctly describes the space charge region formed at the silicon side of the interface.
K C Chen - One of the best experts on this subject based on the ideXlab platform.
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a study on the cavitation resistance of ion nitrided steel
Wear, 2002Co-Authors: W H Huang, K C ChenAbstract:Abstract Cavitation is a common deterioration process of a material resulting from high-speed fluid Attack. Surface treatments are usually preferably considered to promote cavitation resistance because economic reason and longer durability consideration. The cavitation behaviors of ion-nitrided carbon steel, the response of nitriding layer to various cavitation environments, in particular, were studied. An ASTM G32-85 standard method was conducted to proceed cavitation test in fresh water, 3.5 wt.% NaCl and 3.5 wt.% HCl aqueous electrolytes, respectively. Experimental results show that nitriding of steel would reduce the cavitation rate of the S48C steel in fresh water due to the hard nitrided surface which could resist mechanical damage. Electrochemical corrosion plays a part in the case of 3.5 wt.% NaCl and 3.5 wt.% HCl electrolytes. Ion-nitrided specimens in the former electrolyte, therefore, become less protective than in fresh water with, however, lower cavitation rate than blank steel. Ion-nitrided specimen in the later electrolyte subjecting primarily to Electrochemical Attack to the nitriding layer, which has high corrosion current, shows inferior cavitation resistance than blank substrate. Therefore, the method of surface modification should be properly determined depending on what electrolyte would be used. Ion nitriding of carbon steel in our case is suitable for fresh water and 3.5 wt.% NaCl electrolyte, but not for 3.5 wt.% HCl electrolyte.