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K Lu - One of the best experts on this subject based on the ideXlab platform.
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Fatigue behaviors of AISI 316L stainless steel with a gradient Nanostructured Surface layer
Acta Materialia, 2015Co-Authors: Hao Huang, Z B Wang, Jian Lu, K LuAbstract:Abstract By means of Surface mechanical rolling treatment (SMRT), a gradient Nanostructured (GNS) Surface layer was formed on AISI 316L stainless steel. The mean grain size is ∼30 nm in the topmost Surface layer and increases with depth. Tension–compression fatigue measurements were performed on the SMRT sample under the stress-controlled mode. In comparison with the coarse-grained sample, the fatigue strength of the SMRT sample is significantly enhanced in both the low- and high- cycling fatigue regimes. Meanwhile, the fatigue ratio is evidently elevated with an increasing tensile strength in the SMRT sample. The initiation and growth of cracks, the cyclic deformation behaviors, as well as effects of strength and residual stresses, have been investigated to clarify the fatigue mechanism of the SMRT sample. The results emphasized the GNS Surface layer enhances the fatigue property by suppressing the initiation of cracks and accommodating a remarkable cyclic plastic strain amplitude.
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Annealing-induced Grain Refinement in a Nanostructured Ferritic Steel
Journal of Materials Science & Technology, 2012Co-Authors: L. M. Wang, Z B Wang, K LuAbstract:A Nanostructured Surface layer with a mean ferrite grain size of similar to 8 nm was produced on a Fe-9Cr steel by means of Surface mechanical attrition treatment. Upon annealing, ferrite grains coarsen with increasing temperature and their sizes increase to similar to 40 nm at 973 K. Further increasing annealing temperature leads to an obvious reduction of ferrite grain sizes, to similar to 44 nm at 1173 K. The annealing-induced grain refinement is analyzed in terms of phase transformations in the Nanostructured steel.
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interfacial diffusion in cu with a gradient Nanostructured Surface layer
Acta Materialia, 2010Co-Authors: Z B Wang, K Lu, Gerhard Wilde, Sergiy V DivinskiAbstract:Abstract A graded microstructure was produced in the Surface layer of a pure Cu sample by means of Surface mechanical attrition treatment (SMAT) [Wang K, Tao NR, Liu G, Lu J, Lu K. Acta Mater 2006;54:5281.]. The diffusion behavior of 63Ni in such a Surface layer was investigated by the radiotracer technique at temperatures
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characterization and properties of Nanostructured Surface layer in a low carbon steel subjected to Surface mechanical attrition
Journal of Materials Science & Technology, 2009Co-Authors: X P Yong, K Lu, Jian LuAbstract:A Nanostructured Surface layer was synthesized on a low carbon steel by using Surface mechanical attrition (SMA) technique. The refined microstructure of the Surface layer was characterized by means of different techniques, and the hardness variation along the depth was examined. Experimental results show that the microstructure is inhomogeneous along the depth. In the region from top Surface to about 40 mum deep, the grain size increases from about 10 nm to 100 nm. In the adjacent region of about 4080 pm depth, the grain size increases from about 100 nm to 1000 nm. The grain refinement can be associated with the activity of dislocations. After the SMA treatment, the hardness of the Surface layer is enhanced significantly compared with that of the original sample, which can primarily be attributed to the grain refinement.
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chromizing behaviors of a low carbon steel processed by means of Surface mechanical attrition treatment
Acta Materialia, 2005Co-Authors: Z B Wang, Jian Lu, K LuAbstract:A Nanostructured Surface layer of about 20 mu m thick was produced in a low carbon steel plate by means of the Surface mechanical attrition treatment (SMAT). Chromizing behaviors of the SMAT sample were investigated by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Experimental results showed that a much thicker Cr-diffusion layer was obtained in the SMAT sample than in the coarse-grained one after the same chromizing treatment, especially at low temperatures. In the SMAT sample, the formation temperature of chromium compounds was found to be much lower and the amount of chromium carbides was higher than those in the coarse-grained counterpart. The enhanced chromizing kinetics originates from numerous grain boundaries with a high excess stored energy in the Nanostructured Surface layer due to severe plastic deformation during the SMAT. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Jian Lu - One of the best experts on this subject based on the ideXlab platform.
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Enhanced repeated frictional sliding properties in 304 stainless steel with a gradient Nanostructured Surface
Surface & Coatings Technology, 2018Co-Authors: Daniel Bernoulli, Jian LuAbstract:Abstract Surface mechanical attrition treatment (SMAT) is a powerful and practical method to Surface-harden metals and alloys through the generation of a gradient Nanostructured Surface. In this study 304 stainless steel was SMAT processed and the mechanical response upon repeated frictional sliding is studied as well as compared to the mechanical response of untreated as-received 304 stainless steel. The repeated frictional sliding experimental work is complemented by finite-element analysis in order to quantify the stress and strain distribution and to qualitatively determine the elastic-plastic deformation behavior. It is shown that repeated frictional sliding on the SMAT processed 304 stainless steel Surface results in smaller residual depth, pile-up height and friction coefficient but higher maximum stresses compared to the as-received 304 stainless steel. After approximately 30 cycles the residual depth increases only minimally with each additional cycle because of strain hardening and increased contact area. At low cycle numbers the frictional sliding track of the as-received 304 stainless steel meanders and forms slip bands adjacent to the sliding track. Due to instability of the gradient structure of 304 SMAT processed stainless steel, asperities are formed in the inner zone of sliding tracks at increasing cycle numbers.
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Fatigue behaviors of AISI 316L stainless steel with a gradient Nanostructured Surface layer
Acta Materialia, 2015Co-Authors: Hao Huang, Z B Wang, Jian Lu, K LuAbstract:Abstract By means of Surface mechanical rolling treatment (SMRT), a gradient Nanostructured (GNS) Surface layer was formed on AISI 316L stainless steel. The mean grain size is ∼30 nm in the topmost Surface layer and increases with depth. Tension–compression fatigue measurements were performed on the SMRT sample under the stress-controlled mode. In comparison with the coarse-grained sample, the fatigue strength of the SMRT sample is significantly enhanced in both the low- and high- cycling fatigue regimes. Meanwhile, the fatigue ratio is evidently elevated with an increasing tensile strength in the SMRT sample. The initiation and growth of cracks, the cyclic deformation behaviors, as well as effects of strength and residual stresses, have been investigated to clarify the fatigue mechanism of the SMRT sample. The results emphasized the GNS Surface layer enhances the fatigue property by suppressing the initiation of cracks and accommodating a remarkable cyclic plastic strain amplitude.
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characterization and properties of Nanostructured Surface layer in a low carbon steel subjected to Surface mechanical attrition
Journal of Materials Science & Technology, 2009Co-Authors: X P Yong, K Lu, Jian LuAbstract:A Nanostructured Surface layer was synthesized on a low carbon steel by using Surface mechanical attrition (SMA) technique. The refined microstructure of the Surface layer was characterized by means of different techniques, and the hardness variation along the depth was examined. Experimental results show that the microstructure is inhomogeneous along the depth. In the region from top Surface to about 40 mum deep, the grain size increases from about 10 nm to 100 nm. In the adjacent region of about 4080 pm depth, the grain size increases from about 100 nm to 1000 nm. The grain refinement can be associated with the activity of dislocations. After the SMA treatment, the hardness of the Surface layer is enhanced significantly compared with that of the original sample, which can primarily be attributed to the grain refinement.
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chromizing behaviors of a low carbon steel processed by means of Surface mechanical attrition treatment
Acta Materialia, 2005Co-Authors: Z B Wang, Jian Lu, K LuAbstract:A Nanostructured Surface layer of about 20 mu m thick was produced in a low carbon steel plate by means of the Surface mechanical attrition treatment (SMAT). Chromizing behaviors of the SMAT sample were investigated by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Experimental results showed that a much thicker Cr-diffusion layer was obtained in the SMAT sample than in the coarse-grained one after the same chromizing treatment, especially at low temperatures. In the SMAT sample, the formation temperature of chromium compounds was found to be much lower and the amount of chromium carbides was higher than those in the coarse-grained counterpart. The enhanced chromizing kinetics originates from numerous grain boundaries with a high excess stored energy in the Nanostructured Surface layer due to severe plastic deformation during the SMAT. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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Nanostructured Surface layer on metallic materials induced by Surface mechanical attrition treatment
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004Co-Authors: K Lu, Jian LuAbstract:In terms of the grain refinement mechanism induced by plastic straining, a novel Surface mechanical attrition treatment (SMAT) was developed for synthesizing a Nanostructured Surface layer on metallic materials in order to upgrade the overall properties and performance. In this paper, the SMAT technique and the microstructure of the SMAT Surface layer will be described. The grain refinement mechanism of the Surface layer during the SMAT will be analyzed in terms of the microstructure observations in several typical materials. Obvious enhancements in mechanical properties and tribological properties of the Nanostructured Surface layer in different materials were observed. Further development and prospects will be addressed with respect to the SMAT as well as the performance and technological applications of the engineering materials with the Nanostructured Surface layer.
Ryan Enright - One of the best experts on this subject based on the ideXlab platform.
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jumping droplet enhanced condensation on scalable superhydrophobic Nanostructured Surfaces
Nano Letters, 2013Co-Authors: Nenad Miljkovic, Ryan Enright, Youngsuk Nam, Ken Lopez, Nicholas G. Dou, Jean Sack, Evelyn N. WangAbstract:When droplets coalesce on a superhydrophobic Nanostructured Surface, the resulting droplet can jump from the Surface due to the release of excess Surface energy. If designed properly, these superhydrophobic Nanostructured Surfaces can not only allow for easy droplet removal at micrometric length scales during condensation but also promise to enhance heat transfer performance. However, the rationale for the design of an ideal Nanostructured Surface as well as heat transfer experiments demonstrating the advantage of this jumping behavior are lacking. Here, we show that silanized copper oxide Surfaces created via a simple fabrication method can achieve highly efficient jumping-droplet condensation heat transfer. We experimentally demonstrated a 25% higher overall heat flux and 30% higher condensation heat transfer coefficient compared to state-of-the-art hydrophobic condensing Surfaces at low supersaturations (<1.12). This work not only shows significant condensation heat transfer enhancement but also promises a low cost and scalable approach to increase efficiency for applications such as atmospheric water harvesting and dehumidification. Furthermore, the results offer insights and an avenue to achieve high flux superhydrophobic condensation.
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jumping droplet enhanced condensation on scalable superhydrophobic Nanostructured Surfaces
Nano Letters, 2013Co-Authors: Nenad Miljkovic, Ryan Enright, Ken Lopez, Jean Sack, Evelyn N. WangAbstract:When droplets coalesce on a superhydrophobic Nanostructured Surface, the resulting droplet can jump from the Surface due to the release of excess Surface energy. If designed properly, these superhydrophobic Nanostructured Surfaces can not only allow for easy droplet removal at micrometric length scales during condensation but also promise to enhance heat transfer performance. However, the rationale for the design of an ideal Nanostructured Surface as well as heat transfer experiments demonstrating the advantage of this jumping behavior are lacking. Here, we show that silanized copper oxide Surfaces created via a simple fabrication method can achieve highly efficient jumping-droplet condensation heat transfer. We experimentally demonstrated a 25% higher overall heat flux and 30% higher condensation heat transfer coefficient compared to state-of-the-art hydrophobic condensing Surfaces at low supersaturations (<1.12). This work not only shows significant condensation heat transfer enhancement but also promis...
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Jumping-Droplet-Enhanced Condensation on Scalable Superhydrophobic Nanostructured Surfaces
Nano Letters, 2012Co-Authors: Nenad Miljkovic, Ryan Enright, Youngsuk Nam, Ken Lopez, Nicholas G. Dou, Jean Sack, Evelyn N. WangAbstract:When droplets coalesce on a superhydrophobic Nanostructured Surface, the resulting droplet can jump from the Surface due to the release of excess Surface energy. If designed properly, these superhydrophobic Nanostructured Surfaces can not only allow for easy droplet removal at micrometric length scales during condensation but also promise to enhance heat transfer performance. However, the rationale for the design of an ideal Nanostructured Surface as well as heat transfer experiments demonstrating the advantage of this jumping behavior are lacking. Here, we show that silanized copper oxide Surfaces created via a simple fabrication method can achieve highly efficient jumping-droplet condensation heat transfer. We experimentally demonstrated a 25% higher overall heat flux and 30% higher condensation heat transfer coefficient compared to state-of-the-art hydrophobic condensing Surfaces at low supersaturations (
Evelyn N. Wang - One of the best experts on this subject based on the ideXlab platform.
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jumping droplet enhanced condensation on scalable superhydrophobic Nanostructured Surfaces
Nano Letters, 2013Co-Authors: Nenad Miljkovic, Ryan Enright, Youngsuk Nam, Ken Lopez, Nicholas G. Dou, Jean Sack, Evelyn N. WangAbstract:When droplets coalesce on a superhydrophobic Nanostructured Surface, the resulting droplet can jump from the Surface due to the release of excess Surface energy. If designed properly, these superhydrophobic Nanostructured Surfaces can not only allow for easy droplet removal at micrometric length scales during condensation but also promise to enhance heat transfer performance. However, the rationale for the design of an ideal Nanostructured Surface as well as heat transfer experiments demonstrating the advantage of this jumping behavior are lacking. Here, we show that silanized copper oxide Surfaces created via a simple fabrication method can achieve highly efficient jumping-droplet condensation heat transfer. We experimentally demonstrated a 25% higher overall heat flux and 30% higher condensation heat transfer coefficient compared to state-of-the-art hydrophobic condensing Surfaces at low supersaturations (<1.12). This work not only shows significant condensation heat transfer enhancement but also promises a low cost and scalable approach to increase efficiency for applications such as atmospheric water harvesting and dehumidification. Furthermore, the results offer insights and an avenue to achieve high flux superhydrophobic condensation.
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jumping droplet enhanced condensation on scalable superhydrophobic Nanostructured Surfaces
Nano Letters, 2013Co-Authors: Nenad Miljkovic, Ryan Enright, Ken Lopez, Jean Sack, Evelyn N. WangAbstract:When droplets coalesce on a superhydrophobic Nanostructured Surface, the resulting droplet can jump from the Surface due to the release of excess Surface energy. If designed properly, these superhydrophobic Nanostructured Surfaces can not only allow for easy droplet removal at micrometric length scales during condensation but also promise to enhance heat transfer performance. However, the rationale for the design of an ideal Nanostructured Surface as well as heat transfer experiments demonstrating the advantage of this jumping behavior are lacking. Here, we show that silanized copper oxide Surfaces created via a simple fabrication method can achieve highly efficient jumping-droplet condensation heat transfer. We experimentally demonstrated a 25% higher overall heat flux and 30% higher condensation heat transfer coefficient compared to state-of-the-art hydrophobic condensing Surfaces at low supersaturations (<1.12). This work not only shows significant condensation heat transfer enhancement but also promis...
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Jumping-Droplet-Enhanced Condensation on Scalable Superhydrophobic Nanostructured Surfaces
Nano Letters, 2012Co-Authors: Nenad Miljkovic, Ryan Enright, Youngsuk Nam, Ken Lopez, Nicholas G. Dou, Jean Sack, Evelyn N. WangAbstract:When droplets coalesce on a superhydrophobic Nanostructured Surface, the resulting droplet can jump from the Surface due to the release of excess Surface energy. If designed properly, these superhydrophobic Nanostructured Surfaces can not only allow for easy droplet removal at micrometric length scales during condensation but also promise to enhance heat transfer performance. However, the rationale for the design of an ideal Nanostructured Surface as well as heat transfer experiments demonstrating the advantage of this jumping behavior are lacking. Here, we show that silanized copper oxide Surfaces created via a simple fabrication method can achieve highly efficient jumping-droplet condensation heat transfer. We experimentally demonstrated a 25% higher overall heat flux and 30% higher condensation heat transfer coefficient compared to state-of-the-art hydrophobic condensing Surfaces at low supersaturations (
Z B Wang - One of the best experts on this subject based on the ideXlab platform.
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Fatigue behaviors of AISI 316L stainless steel with a gradient Nanostructured Surface layer
Acta Materialia, 2015Co-Authors: Hao Huang, Z B Wang, Jian Lu, K LuAbstract:Abstract By means of Surface mechanical rolling treatment (SMRT), a gradient Nanostructured (GNS) Surface layer was formed on AISI 316L stainless steel. The mean grain size is ∼30 nm in the topmost Surface layer and increases with depth. Tension–compression fatigue measurements were performed on the SMRT sample under the stress-controlled mode. In comparison with the coarse-grained sample, the fatigue strength of the SMRT sample is significantly enhanced in both the low- and high- cycling fatigue regimes. Meanwhile, the fatigue ratio is evidently elevated with an increasing tensile strength in the SMRT sample. The initiation and growth of cracks, the cyclic deformation behaviors, as well as effects of strength and residual stresses, have been investigated to clarify the fatigue mechanism of the SMRT sample. The results emphasized the GNS Surface layer enhances the fatigue property by suppressing the initiation of cracks and accommodating a remarkable cyclic plastic strain amplitude.
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Annealing-induced Grain Refinement in a Nanostructured Ferritic Steel
Journal of Materials Science & Technology, 2012Co-Authors: L. M. Wang, Z B Wang, K LuAbstract:A Nanostructured Surface layer with a mean ferrite grain size of similar to 8 nm was produced on a Fe-9Cr steel by means of Surface mechanical attrition treatment. Upon annealing, ferrite grains coarsen with increasing temperature and their sizes increase to similar to 40 nm at 973 K. Further increasing annealing temperature leads to an obvious reduction of ferrite grain sizes, to similar to 44 nm at 1173 K. The annealing-induced grain refinement is analyzed in terms of phase transformations in the Nanostructured steel.
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interfacial diffusion in cu with a gradient Nanostructured Surface layer
Acta Materialia, 2010Co-Authors: Z B Wang, K Lu, Gerhard Wilde, Sergiy V DivinskiAbstract:Abstract A graded microstructure was produced in the Surface layer of a pure Cu sample by means of Surface mechanical attrition treatment (SMAT) [Wang K, Tao NR, Liu G, Lu J, Lu K. Acta Mater 2006;54:5281.]. The diffusion behavior of 63Ni in such a Surface layer was investigated by the radiotracer technique at temperatures
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Gaseous nitriding of iron with a Nanostructured Surface layer
Scripta Materialia, 2007Co-Authors: W.p. Tong, Z B Wang, C.z. Liu, Wenzhao Wang, Nairong Tao, Liang ZuoAbstract:A Nanostructured Surface layer was formed on a pure iron plate by means of Surface mechanical attrition treatment (SMAT). It was found that a SMAT iron sample developed a nitrided layer twice as thick as that on a coarse-grained sample under the same gaseous nitriding conditions (500 °C for 2 h), which is attributed to the fast diffusion of nitrogen along grain boundaries in the Nanostructured iron. The nitrided layer of SMAT sample exhibited a high hardness and an excellent wear resistance.
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chromizing behaviors of a low carbon steel processed by means of Surface mechanical attrition treatment
Acta Materialia, 2005Co-Authors: Z B Wang, Jian Lu, K LuAbstract:A Nanostructured Surface layer of about 20 mu m thick was produced in a low carbon steel plate by means of the Surface mechanical attrition treatment (SMAT). Chromizing behaviors of the SMAT sample were investigated by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Experimental results showed that a much thicker Cr-diffusion layer was obtained in the SMAT sample than in the coarse-grained one after the same chromizing treatment, especially at low temperatures. In the SMAT sample, the formation temperature of chromium compounds was found to be much lower and the amount of chromium carbides was higher than those in the coarse-grained counterpart. The enhanced chromizing kinetics originates from numerous grain boundaries with a high excess stored energy in the Nanostructured Surface layer due to severe plastic deformation during the SMAT. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
