The Experts below are selected from a list of 11397 Experts worldwide ranked by ideXlab platform
Karl Schulte - One of the best experts on this subject based on the ideXlab platform.
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investigation of shear Thinning Behavior and microstructures of mwcnt epoxy and cnf epoxy suspensions under steady shear conditions
European Polymer Journal, 2012Co-Authors: Tomohiro Yokozeki, Sonja Carolin Schulz, Samuel T. Buschhorn, Karl SchulteAbstract:Abstract This report investigates the steady-state viscosities of multiwall carbon nanotube (MWCNT)/epoxy and carbon nanofiber (CNF)/epoxy suspensions with varying filler concentrations under different shear rates at various temperatures. In situ observation of filler networks suggests the build-up of shear induced MWCNT and CNF agglomerates at low shear rates, which correlates with the measured shear Thinning Behavior. The agglomeration process in MWCNT/epoxy suspensions is enhanced at lower shear rates in the case of higher temperatures, whereas, at high shear rates, both nano-fillers show good dispersion. Shear Thinning Behavior is observed for both types of fillers, and shear Thinning exponential parameters are evaluated as a function of filler content. The shear Thinning exponent increases in conjunction with increase in filler content, but it is found to saturate at a specific value, independently of filler material. Finally, the micromechanical elasticity-based analogy model is applied to the prediction of steady state shear viscosity of suspensions at higher shear rates with the assumption of complete dispersion and alignment of individual nano-fillers in suspensions. The predicted viscosities and the experimental data at higher shear rates are compared. The results conclude that fairly good agreement can be seen for the cases of CNF/epoxy suspensions at lower temperatures, whereas MWCNT/epoxy suspensions and CNF/epoxy suspensions at higher temperatures show discrepancy between the prediction and the experimental data.
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Investigation of shear Thinning Behavior and microstructures of MWCNT/epoxy and CNF/epoxy suspensions under steady shear conditions
European Polymer Journal, 2012Co-Authors: Tomohiro Yokozeki, Sonja Carolin Schulz, Samuel T. Buschhorn, Karl SchulteAbstract:Abstract This report investigates the steady-state viscosities of multiwall carbon nanotube (MWCNT)/epoxy and carbon nanofiber (CNF)/epoxy suspensions with varying filler concentrations under different shear rates at various temperatures. In situ observation of filler networks suggests the build-up of shear induced MWCNT and CNF agglomerates at low shear rates, which correlates with the measured shear Thinning Behavior. The agglomeration process in MWCNT/epoxy suspensions is enhanced at lower shear rates in the case of higher temperatures, whereas, at high shear rates, both nano-fillers show good dispersion. Shear Thinning Behavior is observed for both types of fillers, and shear Thinning exponential parameters are evaluated as a function of filler content. The shear Thinning exponent increases in conjunction with increase in filler content, but it is found to saturate at a specific value, independently of filler material. Finally, the micromechanical elasticity-based analogy model is applied to the prediction of steady state shear viscosity of suspensions at higher shear rates with the assumption of complete dispersion and alignment of individual nano-fillers in suspensions. The predicted viscosities and the experimental data at higher shear rates are compared. The results conclude that fairly good agreement can be seen for the cases of CNF/epoxy suspensions at lower temperatures, whereas MWCNT/epoxy suspensions and CNF/epoxy suspensions at higher temperatures show discrepancy between the prediction and the experimental data.
Seon-hyo Kim - One of the best experts on this subject based on the ideXlab platform.
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Advances in Molten Slags, Fluxes, and Salts: Proceedings of the 10th International Conference on Molten Slags, Fluxes and Salts - Viscoelastic Properties of Calcium Silicate Based Mold Fluxes at 1623K
Advances in Molten Slags Fluxes and Salts: Proceedings of the 10th International Conference on Molten Slags Fluxes and Salts 2016, 2016Co-Authors: Seung-ho Shin, Jung-wook Cho, Seon-hyo KimAbstract:CaO-SiO2-CaF2 based flux in a continuous steel caster has to show dual viscous functions to minimize slab defects - high viscosity enough to avoid flux entrainment at mold top surface and low viscosity enough to maximize lubrication capability at oscillated mold wall region. Liquid flux could show a shear Thinning Behavior when its viscosity decreases with increasing shear rates. Flux viscosity was measured by a rotational type viscometer as a function of shear rates. Raman and XPS analysis were employed to understand structural changes of flux for correlating with shear Thinning Behavior. The present work has focused on developing an optimum mold flux system with strong shear Thinning Behavior. The strong shear Thinning Behavior appropriate for dual viscous functions could be achieved by incorporating borate or silicon nitride into the flux. The flux compositions with a strong shear Thinning Behavior will be presented from the viewpoint of clean slab production.
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Shear Thinning Behavior of Calcium Silicate-Based Mold Fluxes at 1623 K
Journal of the American Ceramic Society, 2014Co-Authors: Seung-ho Shin, Jung-wook Cho, Seon-hyo KimAbstract:There have been consistent efforts on understanding rheological Behavior of molten mold flux, used in continuous casting of steels. It is prevalent view that molten mold flux shows non-Newtonian Behavior, meaning that the viscosity varies with shear rate history. Hence, the present study attempts to evaluate shear Thinning, which is one of the characteristic non-Newtonian Behaviors, by measuring its viscosity with a rotating type viscometer at 1623 K. Furthermore, Raman spectroscopy analysis is used to appreciate the structure of molten mold flux and shear Thinning. Mold fluxes tested reveal definite shear Thinning characteristic of decreasing viscosity with increasing shear rate. The degree of shear Thinning has been well quantified by Oswald-De Waele power law model. Lastly, the degree of polymerization, obtained from Raman spectroscopic data has proportional relationship with degree of shear Thinning in the range of 1–5 s−1 shear rate. Also, it has a downward parabolic relationship with degree of shear Thinning at entire shear rate ranges up to 100 s−1. This study also verifies possibility to use shear Thinning Behavior on actual continuous casting process.
Xingjuan Wang - One of the best experts on this subject based on the ideXlab platform.
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Shear-Thinning Behavior of the CaO–SiO 2 –CaF 2 –Si 3 N 4 system mold flux and its practical application
International Journal of Minerals Metallurgy and Materials, 2017Co-Authors: Zhi-peng Yuan, Liguang Zhu, Yi-hua Han, Xingjuan WangAbstract:Satisfying the mold-flux performance requirements for high-speed continuous casting necessitates the development of a new non-Newtonian-fluid mold flux with shear-Thinning Behavior, i.e., a mold flux whose viscosity is relatively high under lower shear rates and relatively low under higher shear rates. In this work, a mold flux that exhibits shear-Thinning Behavior was developed by adding different amounts of Si3N4 to the CaO–SiO2–CaF2 mold flux. The shear-Thinning Behavior was investigated using a rotational viscometer. In addition, the microstructure of the newly prepared slags was studied by high-temperature Raman spectroscopy and X-ray photoelectron spectroscopy. The results showed that the mechanism of shear-Thinning was attributable to a temporary viscosity loss caused by the one-way shear stress, whereas the corresponding magnitude of shear-Thinning was closely related to the degree of polymerization (DP). Finally, the non-Newtonian fluid mold flux was used for laboratory casting tests, which revealed that the mold flux could reduce slag entrapment and positively affect the continuous casting optimization.
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shear Thinning Behavior of the cao sio 2 caf 2 si 3 n 4 system mold flux and its practical application
International Journal of Minerals Metallurgy and Materials, 2017Co-Authors: Zhi-peng Yuan, Liguang Zhu, Yi-hua Han, Xingjuan WangAbstract:Satisfying the mold-flux performance requirements for high-speed continuous casting necessitates the development of a new non-Newtonian-fluid mold flux with shear-Thinning Behavior, i.e., a mold flux whose viscosity is relatively high under lower shear rates and relatively low under higher shear rates. In this work, a mold flux that exhibits shear-Thinning Behavior was developed by adding different amounts of Si3N4 to the CaO–SiO2–CaF2 mold flux. The shear-Thinning Behavior was investigated using a rotational viscometer. In addition, the microstructure of the newly prepared slags was studied by high-temperature Raman spectroscopy and X-ray photoelectron spectroscopy. The results showed that the mechanism of shear-Thinning was attributable to a temporary viscosity loss caused by the one-way shear stress, whereas the corresponding magnitude of shear-Thinning was closely related to the degree of polymerization (DP). Finally, the non-Newtonian fluid mold flux was used for laboratory casting tests, which revealed that the mold flux could reduce slag entrapment and positively affect the continuous casting optimization.
Tomohiro Yokozeki - One of the best experts on this subject based on the ideXlab platform.
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investigation of shear Thinning Behavior and microstructures of mwcnt epoxy and cnf epoxy suspensions under steady shear conditions
European Polymer Journal, 2012Co-Authors: Tomohiro Yokozeki, Sonja Carolin Schulz, Samuel T. Buschhorn, Karl SchulteAbstract:Abstract This report investigates the steady-state viscosities of multiwall carbon nanotube (MWCNT)/epoxy and carbon nanofiber (CNF)/epoxy suspensions with varying filler concentrations under different shear rates at various temperatures. In situ observation of filler networks suggests the build-up of shear induced MWCNT and CNF agglomerates at low shear rates, which correlates with the measured shear Thinning Behavior. The agglomeration process in MWCNT/epoxy suspensions is enhanced at lower shear rates in the case of higher temperatures, whereas, at high shear rates, both nano-fillers show good dispersion. Shear Thinning Behavior is observed for both types of fillers, and shear Thinning exponential parameters are evaluated as a function of filler content. The shear Thinning exponent increases in conjunction with increase in filler content, but it is found to saturate at a specific value, independently of filler material. Finally, the micromechanical elasticity-based analogy model is applied to the prediction of steady state shear viscosity of suspensions at higher shear rates with the assumption of complete dispersion and alignment of individual nano-fillers in suspensions. The predicted viscosities and the experimental data at higher shear rates are compared. The results conclude that fairly good agreement can be seen for the cases of CNF/epoxy suspensions at lower temperatures, whereas MWCNT/epoxy suspensions and CNF/epoxy suspensions at higher temperatures show discrepancy between the prediction and the experimental data.
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Investigation of shear Thinning Behavior and microstructures of MWCNT/epoxy and CNF/epoxy suspensions under steady shear conditions
European Polymer Journal, 2012Co-Authors: Tomohiro Yokozeki, Sonja Carolin Schulz, Samuel T. Buschhorn, Karl SchulteAbstract:Abstract This report investigates the steady-state viscosities of multiwall carbon nanotube (MWCNT)/epoxy and carbon nanofiber (CNF)/epoxy suspensions with varying filler concentrations under different shear rates at various temperatures. In situ observation of filler networks suggests the build-up of shear induced MWCNT and CNF agglomerates at low shear rates, which correlates with the measured shear Thinning Behavior. The agglomeration process in MWCNT/epoxy suspensions is enhanced at lower shear rates in the case of higher temperatures, whereas, at high shear rates, both nano-fillers show good dispersion. Shear Thinning Behavior is observed for both types of fillers, and shear Thinning exponential parameters are evaluated as a function of filler content. The shear Thinning exponent increases in conjunction with increase in filler content, but it is found to saturate at a specific value, independently of filler material. Finally, the micromechanical elasticity-based analogy model is applied to the prediction of steady state shear viscosity of suspensions at higher shear rates with the assumption of complete dispersion and alignment of individual nano-fillers in suspensions. The predicted viscosities and the experimental data at higher shear rates are compared. The results conclude that fairly good agreement can be seen for the cases of CNF/epoxy suspensions at lower temperatures, whereas MWCNT/epoxy suspensions and CNF/epoxy suspensions at higher temperatures show discrepancy between the prediction and the experimental data.
Seung-ho Shin - One of the best experts on this subject based on the ideXlab platform.
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Advances in Molten Slags, Fluxes, and Salts: Proceedings of the 10th International Conference on Molten Slags, Fluxes and Salts - Viscoelastic Properties of Calcium Silicate Based Mold Fluxes at 1623K
Advances in Molten Slags Fluxes and Salts: Proceedings of the 10th International Conference on Molten Slags Fluxes and Salts 2016, 2016Co-Authors: Seung-ho Shin, Jung-wook Cho, Seon-hyo KimAbstract:CaO-SiO2-CaF2 based flux in a continuous steel caster has to show dual viscous functions to minimize slab defects - high viscosity enough to avoid flux entrainment at mold top surface and low viscosity enough to maximize lubrication capability at oscillated mold wall region. Liquid flux could show a shear Thinning Behavior when its viscosity decreases with increasing shear rates. Flux viscosity was measured by a rotational type viscometer as a function of shear rates. Raman and XPS analysis were employed to understand structural changes of flux for correlating with shear Thinning Behavior. The present work has focused on developing an optimum mold flux system with strong shear Thinning Behavior. The strong shear Thinning Behavior appropriate for dual viscous functions could be achieved by incorporating borate or silicon nitride into the flux. The flux compositions with a strong shear Thinning Behavior will be presented from the viewpoint of clean slab production.
-
Shear Thinning Behavior of Calcium Silicate-Based Mold Fluxes at 1623 K
Journal of the American Ceramic Society, 2014Co-Authors: Seung-ho Shin, Jung-wook Cho, Seon-hyo KimAbstract:There have been consistent efforts on understanding rheological Behavior of molten mold flux, used in continuous casting of steels. It is prevalent view that molten mold flux shows non-Newtonian Behavior, meaning that the viscosity varies with shear rate history. Hence, the present study attempts to evaluate shear Thinning, which is one of the characteristic non-Newtonian Behaviors, by measuring its viscosity with a rotating type viscometer at 1623 K. Furthermore, Raman spectroscopy analysis is used to appreciate the structure of molten mold flux and shear Thinning. Mold fluxes tested reveal definite shear Thinning characteristic of decreasing viscosity with increasing shear rate. The degree of shear Thinning has been well quantified by Oswald-De Waele power law model. Lastly, the degree of polymerization, obtained from Raman spectroscopic data has proportional relationship with degree of shear Thinning in the range of 1–5 s−1 shear rate. Also, it has a downward parabolic relationship with degree of shear Thinning at entire shear rate ranges up to 100 s−1. This study also verifies possibility to use shear Thinning Behavior on actual continuous casting process.
