The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Nicol E. Mcgruer - One of the best experts on this subject based on the ideXlab platform.
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Interfacial Shear Stress between a single-walled carbon nanotube and a gold surface after different physical treatments.
Journal of colloid and interface science, 2015Co-Authors: Huiyan Pan, George G. Adams, Nicol E. McgruerAbstract:Abstract The Interfacial Shear Stress between gold and dielectrophoretically assembled single-walled carbon nanotubes can be increased by annealing in N2, by e-beam irradiation, or by e-beam deposition of carbon. For the first time this increase has been measured, using a technique developed by this group that is based on NEMS cantilever measurements combined with modeling. Annealing increases the Shear Stress by more than a factor of 3 over its value of 87 MPa for untreated gold surfaces, while e-beam irradiation increases the Shear Stress by more than a factor of 2 and carbon deposition increases the Shear Stress by a smaller amount.
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Interfacial Shear Stress between single-walled carbon nanotubes and gold surfaces with and without an alkanethiol monolayer.
Journal of colloid and interface science, 2013Co-Authors: Huiyan Pan, George G. Adams, Glen P. Miller, Nicol E. McgruerAbstract:A novel and effective technique is developed to make the first determination of Shear Stress between dielectrophoretically assembled single-walled carbon nanotubes (SWNTs) and surfaces. The results demonstrate that we can vary the Shear Stress by a factor of 20 by functionalizing a gold surface with different alkanethiols. The Interfacial Shear Stress between a small bundle of SWNTs and a gold surface with and without self-assembled monolayers of alkanethiol (2-phenylethanethiol or 2-aminoethanethiol) is determined. The measurements are based on simple NEMS cantilever beams, a nanomanipulator, and a scanning electron microscope (SEM). It is emphasized that the measured quantity is the slack in the nanotube (not the Shear Stress) induced by the nanomanipulation. The Shear Stress is determined from the slack through a mechanics model. An average Shear Stress of 87 MPa between SWNTs and gold surfaces is obtained. For the tests on the self-assembled 2-aminoethanethiol surface, an average Shear Stress of 142 MPa is obtained. For the self-assembled 2-phenylethanethiol surface, the Shear Stress is determined to be around 7.2 MPa with an estimated work of adhesion of 0.5 J/m(2).
Huiyan Pan - One of the best experts on this subject based on the ideXlab platform.
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Interfacial Shear Stress between a single-walled carbon nanotube and a gold surface after different physical treatments.
Journal of colloid and interface science, 2015Co-Authors: Huiyan Pan, George G. Adams, Nicol E. McgruerAbstract:Abstract The Interfacial Shear Stress between gold and dielectrophoretically assembled single-walled carbon nanotubes can be increased by annealing in N2, by e-beam irradiation, or by e-beam deposition of carbon. For the first time this increase has been measured, using a technique developed by this group that is based on NEMS cantilever measurements combined with modeling. Annealing increases the Shear Stress by more than a factor of 3 over its value of 87 MPa for untreated gold surfaces, while e-beam irradiation increases the Shear Stress by more than a factor of 2 and carbon deposition increases the Shear Stress by a smaller amount.
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Interfacial Shear Stress between single-walled carbon nanotubes and gold surfaces with and without an alkanethiol monolayer.
Journal of colloid and interface science, 2013Co-Authors: Huiyan Pan, George G. Adams, Glen P. Miller, Nicol E. McgruerAbstract:A novel and effective technique is developed to make the first determination of Shear Stress between dielectrophoretically assembled single-walled carbon nanotubes (SWNTs) and surfaces. The results demonstrate that we can vary the Shear Stress by a factor of 20 by functionalizing a gold surface with different alkanethiols. The Interfacial Shear Stress between a small bundle of SWNTs and a gold surface with and without self-assembled monolayers of alkanethiol (2-phenylethanethiol or 2-aminoethanethiol) is determined. The measurements are based on simple NEMS cantilever beams, a nanomanipulator, and a scanning electron microscope (SEM). It is emphasized that the measured quantity is the slack in the nanotube (not the Shear Stress) induced by the nanomanipulation. The Shear Stress is determined from the slack through a mechanics model. An average Shear Stress of 87 MPa between SWNTs and gold surfaces is obtained. For the tests on the self-assembled 2-aminoethanethiol surface, an average Shear Stress of 142 MPa is obtained. For the self-assembled 2-phenylethanethiol surface, the Shear Stress is determined to be around 7.2 MPa with an estimated work of adhesion of 0.5 J/m(2).
George G. Adams - One of the best experts on this subject based on the ideXlab platform.
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Interfacial Shear Stress between a single-walled carbon nanotube and a gold surface after different physical treatments.
Journal of colloid and interface science, 2015Co-Authors: Huiyan Pan, George G. Adams, Nicol E. McgruerAbstract:Abstract The Interfacial Shear Stress between gold and dielectrophoretically assembled single-walled carbon nanotubes can be increased by annealing in N2, by e-beam irradiation, or by e-beam deposition of carbon. For the first time this increase has been measured, using a technique developed by this group that is based on NEMS cantilever measurements combined with modeling. Annealing increases the Shear Stress by more than a factor of 3 over its value of 87 MPa for untreated gold surfaces, while e-beam irradiation increases the Shear Stress by more than a factor of 2 and carbon deposition increases the Shear Stress by a smaller amount.
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Interfacial Shear Stress between single-walled carbon nanotubes and gold surfaces with and without an alkanethiol monolayer.
Journal of colloid and interface science, 2013Co-Authors: Huiyan Pan, George G. Adams, Glen P. Miller, Nicol E. McgruerAbstract:A novel and effective technique is developed to make the first determination of Shear Stress between dielectrophoretically assembled single-walled carbon nanotubes (SWNTs) and surfaces. The results demonstrate that we can vary the Shear Stress by a factor of 20 by functionalizing a gold surface with different alkanethiols. The Interfacial Shear Stress between a small bundle of SWNTs and a gold surface with and without self-assembled monolayers of alkanethiol (2-phenylethanethiol or 2-aminoethanethiol) is determined. The measurements are based on simple NEMS cantilever beams, a nanomanipulator, and a scanning electron microscope (SEM). It is emphasized that the measured quantity is the slack in the nanotube (not the Shear Stress) induced by the nanomanipulation. The Shear Stress is determined from the slack through a mechanics model. An average Shear Stress of 87 MPa between SWNTs and gold surfaces is obtained. For the tests on the self-assembled 2-aminoethanethiol surface, an average Shear Stress of 142 MPa is obtained. For the self-assembled 2-phenylethanethiol surface, the Shear Stress is determined to be around 7.2 MPa with an estimated work of adhesion of 0.5 J/m(2).
E. Buet - One of the best experts on this subject based on the ideXlab platform.
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influence of surface fibre properties and textural organization of a pyrocarbon interphase on the Interfacial Shear Stress of sic sic minicomposites reinforced with hi nicalon s and tyranno sa3 fibres
Journal of The European Ceramic Society, 2014Co-Authors: E. Buet, C. Sauder, D. Sornin, S. Poissonnet, J.-n. Rouzaud, Cathie VixguterlAbstract:Abstract SiC/SiC composites reinforced with 3rd generation SiC fibres (Hi-Nicalon S and Tyranno SA3) are attractive for nuclear applications. The mechanical properties of SiC/SiC minicomposites were studied in relation with the nature of fibres and the textural organization of the pyrocarbon interphase. Two different experimental mechanical procedures were used: the push-out test and the tensile mechanical test. The experimental results demonstrate that the Interfacial Shear Stress is higher for a minicomposite reinforced with Tyranno SA3 fibres. It is also shown that the Interfacial Shear Stress depends on the texture of the carbon interphase. Highly anisotropic pyrocarbon interphase increases the Interfacial Shear Stress. To our knowledge it is the first time that the influence of pyrocarbon texture is observed on SiC/SiC composites using Hi-Nicalon S and Tyranno SA3 fibres. It is also demonstrated that push-out tests are more appropriated than tensile tests to highlight differences of Interfacial Shear Stress measurements.
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Influence of surface fibre properties and textural organization of a pyrocarbon interphase on the Interfacial Shear Stress of SiC/SiC minicomposites reinforced with Hi-Nicalon S and Tyranno SA3 fibres
Journal of the European Ceramic Society, 2014Co-Authors: E. Buet, C. Sauder, D. Sornin, S. Poissonnet, J.-n. Rouzaud, Cathie Vix-guterlAbstract:Abstract SiC/SiC composites reinforced with 3rd generation SiC fibres (Hi-Nicalon S and Tyranno SA3) are attractive for nuclear applications. The mechanical properties of SiC/SiC minicomposites were studied in relation with the nature of fibres and the textural organization of the pyrocarbon interphase. Two different experimental mechanical procedures were used: the push-out test and the tensile mechanical test. The experimental results demonstrate that the Interfacial Shear Stress is higher for a minicomposite reinforced with Tyranno SA3 fibres. It is also shown that the Interfacial Shear Stress depends on the texture of the carbon interphase. Highly anisotropic pyrocarbon interphase increases the Interfacial Shear Stress. To our knowledge it is the first time that the influence of pyrocarbon texture is observed on SiC/SiC composites using Hi-Nicalon S and Tyranno SA3 fibres. It is also demonstrated that push-out tests are more appropriated than tensile tests to highlight differences of Interfacial Shear Stress measurements.
L.m. Portela - One of the best experts on this subject based on the ideXlab platform.
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Prediction of the Interfacial Shear-Stress in vertical annular flow
International Journal of Multiphase Flow, 2009Co-Authors: R.j. Belt, J.m.c. Van’t Westende, L.m. PortelaAbstract:Many improvements of the Wallis correlation for the Interfacial friction in annular flow have been proposed in the literature. These improvements give in general a better fit to data, however, their physical basis is not always justified. In this work, we present a physical approach to predict the Interfacial Shear-Stress, based on the theory on roughness in single-phase turbulent pipe flows. Using measured Interfacial Shear-Stress data and measured data on roll waves, which provide most of the contribution to the liquid film roughness, we show that the Interfacial Shear-Stress in vertical annular flow is in very close agreement with the theory. We show that the sand-grain roughness of the liquid film is not equal to four times the mean film thickness, as it is assumed in the Wallis correlation. Instead, the sand-grain roughness is proportional to the wave height, and the proportionality constant can be predicted accurately using the roughness density (or solidity). Furthermore, we show that our annular flow, which is in similar conditions to others in the literature, is fully rough. Hence, the bulk Reynolds number should not appear in the prediction of the Interfacial friction coefficient, as is often done in the improvements of the Wallis correlation proposed in the literature.
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Interfacial waves and Shear Stress in vertical upward annular pipe flow
Proceedings of the ICMF 2007 6th International Conference on Multiphase Flow : Leipzig July 9. - 13. 2007, 2007Co-Authors: R.j. Belt, J.m.c. Van’t Westende, L.m. Portela, R F Mudde, R V A Oliemans, Horstmichael PrasserAbstract:In annular pipe-flow, the liquid flows partly as a thin wavy film along the wall, and partly as droplets entrained in the turbulent gas core. The behavior of the interface plays an important role in determining the Interfacial Shear-Stress between the gas and the liquid, and the entrainment of droplets into the gas core. In this work, we use a conductance liquid probe to measure the thickness of the liquid film. These measurements are used to reconstruct the time-evolution of the interface and to develop a simple physically-based model for the Interfacial Shear-Stress. The basic idea of the measurement technique is to impose an electrical potential between a pair of electrodes in contact with the liquid film and measure the resulting current, which is a function of the conductance of the liquid film, hence of its thickness. This measurement technique has been used before, e.g., Jayanti et al. (1990), however, the film thickness was measured only in a few positions. Here, we use an adaptation of the electrode-mesh sensor described in Prasser et al. (1998) with a matrix of 10 measurement locations in the axial direction and 32 in the circumferential direction, and a time resolution of 5000 Hz at each measurement location. This allows an accurate representation of the time evolution of the interface. A snapshot of the interface is shown in figure 1, where we can see the "roll waves", which play a dominant role in annular flow, e.g., Azzopardi (1997). Our results indicate that the roll waves have a random nature, with the pdf for the time-between-waves being well fitted by a gamma distribution. The random nature of the roll waves suggests that the Interfacial Shear-Stress can be modeled by treating the interface as a surface with a random roughness. We show that the Interfacial Shear-Stress can be determined using the classical sand-roughness theory for pipe flows. We present a simple physically-based model that allows us to extend the original Wallis correlation for the Interfacial Shear-Stress (Wallis (1969)) for a wide range of situations, without the need to use ad-hoc "Reynolds number corrections", as often found in the literature.