To advance the understanding of the corrosion behavior of stainless steel bellows in marine atmospheric environments and enhance the precision of service life predictions,this study employs finite element simulations ...To advance the understanding of the corrosion behavior of stainless steel bellows in marine atmospheric environments and enhance the precision of service life predictions,this study employs finite element simulations to investigate the pitting corrosion rates and pit morphologies of bellows peaks and troughs under varying electrolyte film thicknesses.The model incorporates localized electrochemical reactions,oxygen concentration,and homogeneous solution reactions.For improved computational accuracy,the fitted polarization curve data were directly applied as nonlinear boundary conditions on the electrode surface via interpolation functions.Simulation results reveal that the peak regions exhibit faster corrosion rates than the trough regions.With increasing electrolyte film thickness(from 10μm to 500μm),corrosion rates at both peaks and troughs decrease progressively,and after 120 hours of simulation,the maximum corrosion rate at the peaks declines from 0.720 mm/a to 0.130 mm/a,and at the troughs from 0.520 mm/a to 0.120 mm/a,with the disparity in corrosion rates diminishing over time.Furthermore,as corrosion progresses,pits propagate deeper into the substrate,exhibiting both vertical penetration and lateral expansion along the passive film interface,ultimately breaching the substrate.This research offers valuable insights into designing corrosion mitigation strategies for stainless steel bellows in marine environments.展开更多
Background As information technology has advanced and been popularized,open pit mining has rapidly developed toward integration and digitization.The three-dimensional reconstruction technology has been successfully ap...Background As information technology has advanced and been popularized,open pit mining has rapidly developed toward integration and digitization.The three-dimensional reconstruction technology has been successfully applied to geological reconstruction and modeling of surface scenes in open pit mines.However,an integrated modeling method for surface and underground mine sites has not been reported.Methods In this study,we propose an integrated modeling method for open pit mines that fuses a real scene on the surface with an underground geological model.Based on oblique photography,a real-scene model was established on the surface.Based on the surface-stitching method proposed,the upper and lower surfaces and sides of the model were constructed in stages to construct a complete underground three-dimensional geological model,and the aboveground and underground models were registered together to build an integrated open pit mine model.Results The oblique photography method used reconstructed a surface model of an open pit mine using a real scene.The surface-stitching algorithm proposed was compared with the ball-pivoting and Poisson algorithms,and the integrity of the reconstructed model was markedly superior to that of the other two reconstruction methods.In addition,the surface-stitching algorithm was applied to the reconstruction of different formation models and showed good stability and reconstruction efficiency.Finally,the aboveground and underground models were accurately fitted after registration to form an integrated model.Conclusions The proposed method can efficiently establish an integrated open pit model.Based on the integrated model,an open pit auxiliary planning system was designed and realized.It supports the functions of mining planning and output calculation,assists users in mining planning and operation management,and improves production efficiency and management levels.展开更多
The addition of vanadium substantially enhances the strength of the high-nitrogen austenitic stainless steel(HNASS),while maintaining excellent ductility and pitting corrosion resistance.The effects of vanadium microa...The addition of vanadium substantially enhances the strength of the high-nitrogen austenitic stainless steel(HNASS),while maintaining excellent ductility and pitting corrosion resistance.The effects of vanadium microalloying on the microstructure,mechanical properties,and pitting resistance of HNASS were systematically analyzed with a focus on the role of VN during the pitting process.The results suggest that vanadium promoted the precipitation of VN,contributing to grain boundary pinning and grain refinement.As vanadium content increased,the number of precipitates rose,and the average grain size decreased.At lower vanadium content(0-0.2 wt.%),the strength of the material was significantly reinforced with increasing vanadium content,while maintaining excellent ductility and pitting resistance.However,when the vanadium content reached 0.3-0.4 wt.%,precipitates demonstrated a substantially increased number and coarsened,accompanied by the formation of numerous dislocations around the precipitates.This brought about further strength reinforcement but a marked decline in ductility and pitting resistance.Additionally,pitting corrosion was initiated at the matrix-VN interface.Compared to the matrix,VN exhibited higher reactivity and preferentially reacted with Cl−ions,provoking dissolution.However,NH4+generated during the dissolution of VN facilitated repassivation of the material,suppressing further pitting propagation.展开更多
The micro-area characterization experiments like scanning Kelvin probe force microscope(SKPFM)and Kernel average misorientation have the defects of complex sample preparation and occasional errors in test results,whic...The micro-area characterization experiments like scanning Kelvin probe force microscope(SKPFM)and Kernel average misorientation have the defects of complex sample preparation and occasional errors in test results,which makes it impossible to accurately and quickly analyze the pitting behavior induced by inclusions in some cases,prompting attempts to turn to simulation calculation research.The method of calculating band structure and work function can be used to replace current-sensing atomic force microscopy and SKPFM to detect the potential and conductivity of the sample.The band structure results show that Al_(2)O_(3) inclusion is an insulator and non-conductive,and it will not form galvanic corrosion with the matrix.Al_(2)O_(3) inclusion does not dissolve because its work function is higher than that of the matrix.Moreover,the stress concentration of the matrix around the inclusion can be characterized by first-principles calculation coupled with finite element simulation.The results show that the stress concentration degree of the matrix around Al_(2)O_(3) inclusion is serious,and the galvanic corrosion is formed between the high and the low stress concentration areas,which can be used to explain the reason of the pitting induced by Al_(2)O_(3) inclusions.展开更多
Colorectal cancer is a common tumor of the digestive system and is the third leading cause of cancer-related death worldwide.The global incidence of colorectal cancer is currently increasing.In some patients,the tumor...Colorectal cancer is a common tumor of the digestive system and is the third leading cause of cancer-related death worldwide.The global incidence of colorectal cancer is currently increasing.In some patients,the tumor has already spread to nearby organs at the time of diagnosis,with the small intestine and bladder being common sites of invasion.[1,2]The diagnosis of colorectal cancer that has spread to the bladder can be challenging.Aside from a few patients who experience urinary symptoms due to invasion of the bladder trigone or the entire bladder wall,there are no distinct clinical signs,which often leads to misdiagnosis.The following case report details one such instance.展开更多
The M-shaped multi-row pile foundation retaining structure represents an enhanced version of conventional multi-row anti-sliding support systems.To date,the implementation of M-shaped pile configurations in foundation...The M-shaped multi-row pile foundation retaining structure represents an enhanced version of conventional multi-row anti-sliding support systems.To date,the implementation of M-shaped pile configurations in foundation pit excavations has not been extensively investigated,with particularly scant research focusing on their load-bearing mechanisms and stress redistribution characteristics.Furthermore,numerical modeling methodologies for such geometrically optimized pile networks remain underdeveloped compared to practical engineering applications,creating a notable research-practice gap in geotechnical engineering.A comparative finite element analysis was systematically conducted using ABAQUS software to establish three distinct excavation support configurations:single-row cantilever retaining structures,three-row cantilever configurations,and M-shaped multi-row pile foundation systems.Subsequent numerical simulations enabled quantitative comparisons of critical performance indicators,including pile stress distribution patterns,lateral displacement profiles,and bending moment diagrams across different structural typologies.The parametric investigation revealed characteristic mechanical responses associated with each configuration,establishing corresponding mechanical principles governing the interaction between pile topology and soil-structure behavior towers.The findings of this study provide critical references for the design optimization of M-shaped multi-row pile foundation retaining systems.展开更多
Precipitation-strengthened HEAs exhibit outstanding integration of strength and toughness at ambient temperature.Nevertheless,precipitates generally reduce the localized corrosion resistance in aggressive solution env...Precipitation-strengthened HEAs exhibit outstanding integration of strength and toughness at ambient temperature.Nevertheless,precipitates generally reduce the localized corrosion resistance in aggressive solution environments.To solve this problem,a strategy of introducing nano-sized L12 precipitates in CoCrFeNiAlTi HEAs has been proposed in this work.Results demonstrate the pitting corrosion potential can be elevated from 258 mVSCE to 603 mVSCE by increasing the precipitate content to 38 wt.%.Such an improvement in localized corrosion resistance can be attributed to two aspects.Firstly,L12 precipitates tend to be dissolved during the corrosion process,which promotes the heterogeneous nucleation of protective Cr2 O3 due to the rapid deposition of oxides/hydroxides of Al/Ti,and improves the passive film stability due to the Crrich FCC matrix.Secondly,the dissolution kinetic inside the pits can be suppressed on account of the enrichment of Cr element in the FCC matrix,thus inhibiting the pitting growth.In summary,the current work not only reveals the mechanisms of the nano-sized L12 precipitates upon the corrosion behavior,but also provides a strategy for designing corrosion-resistant HEA.展开更多
An effective approach to enhance the surface degradation characteristics of laser powder bed fusion(LPBF)type 420 stainless steel involves the incorporation of spherical cast WC/W_(2)C to create LPBF metal matrix comp...An effective approach to enhance the surface degradation characteristics of laser powder bed fusion(LPBF)type 420 stainless steel involves the incorporation of spherical cast WC/W_(2)C to create LPBF metal matrix composites(MMCs).However,the corrosion be-havior of stainless steel and cast WC/W_(2)C varies inversely across different pH levels,and the phenomenon of pitting corrosion in LPBF MMCs under varying pH conditions remains insufficiently explored.In LPBF 420+5wt%WC/W_(2)C MMCs,pits form adjacent to cast WC/W_(2)C in acidic and neutral environments,attributed to the presence of chromium-rich carbides and galvanic coupling effects.The dis-solution of the reinforced particles facilitates pit nucleation in alkaline conditions.Notably,in-situ reaction layers exhibit superior corro-sion resistance to the matrix or the reinforced particles across all pH levels.The distinct corrosion mechanisms influence the pitting corro-sion behavior,with the corrosion ranking based on critical pitting potential being neutral>alkaline>acidic,contrasting the observed kin-etics of pit growth(alkaline>acidic>neutral).展开更多
Pitting corrosion poses a significant challenge to 9Cr18 high-carbon chromium bearing steel in chloride-rich environments,severely compromising its structural integrity.The study systematically investigates the pittin...Pitting corrosion poses a significant challenge to 9Cr18 high-carbon chromium bearing steel in chloride-rich environments,severely compromising its structural integrity.The study systematically investigates the pitting behaviour of 9Cr18 bearing steel under salt spray conditions,focusing on the progressive evolution of surface morphology and cross-sectional characteristics of pits on finished bearings.Scanning electron microscopy,energy-dispersive spectroscopy and X-ray diffraction were employed to examine the surface morphology,elemental composition and phase structure of corrosion products over varying salt spray exposure durations.The results show that 9Cr18 steel exhibits localized pitting with“volcanic crater”-like pits in the early stage of salt spray corrosion.After 48 h,pitting develops into a“multi-point”pattern,marking the initial transition toward uniform corrosion.Until 240 h,corrosion products completely cover the surface,indicating the complete transformation from localized pitting to uniform corrosion.The high carbon and chromium content in 9Cr18 steel promotes carbide precipitation and uneven distribution in the matrix.Cr-depleted regions near the carbide/matrix interface serve as preferential sites for pitting initiation.The low effective utilization of chromium reduces the overall corrosion resistance of 9Cr18.展开更多
As one of the commonly used technologies in modern civil engineering,the construction technology is becoming more and more widely used with the continuous growth of building height.In the construction process of highr...As one of the commonly used technologies in modern civil engineering,the construction technology is becoming more and more widely used with the continuous growth of building height.In the construction process of highrise buildings,the deep foundation pit support provides the necessary stability for the foundation structure of the building project,and more effectively guarantees the quality of the project.Through the reasonable supporting structure,the deep foundation pit technology can effectively prevent the risk of soil collapse,foundation pit deformation and other risks,and improve the safety factor of the whole construction project.Especially in the high-rise buildings,the deep foundation pit support technology can consolidate the foundation for the long-term stability of the project,and significantly prolong the service life of the building.The continuous development of deep foundation pit construction technology is the inevitable demand of high-rise building construction,and also provides a powerful help for the development of civil engineering industry.Based on this,this paper focuses on the application of deep foundation pit construction technology in civil engineering construction.展开更多
The goal of this research is to develop mine-scale discrete fracture network(DFN)models in which the influence of the spatial heterogeneity of fracture distributions may be investigated on the rock wedge stability of ...The goal of this research is to develop mine-scale discrete fracture network(DFN)models in which the influence of the spatial heterogeneity of fracture distributions may be investigated on the rock wedge stability of an open pit slope.For this purpose,spatially conditioned DFN models were developed for the pit walls at Tasiast mine using comprehensive structural data from the mine.Using Sequential Gaussian Simulation(SGS),volumetric fracture intensities(P32)were modeled across the entire mine site in the form of 3D block models.The simulated P32 block models were used as the input constraints for conditional DFN fracture generation,where the DFN grid dimension is the same as the SGS 3D blocks.The spatially constrained DFN models were further calibrated using aerial fracture intensities(P21)data from the pit walls,obtained by a survey of the pit walls using an unmanned aerial vehicle(UAV)and measured traces of joints from 3D point cloud data.The final DFN model is expected to honor the fracture intensities gathered through different means with optimal model accuracy.Finally,bench-scale and interramp scale rock wedge slope stability analyses were conducted using the calibrated conditional DFN models.This work proves the significance of conditioned DFN models in rock wedge stability analysis.Such models provide detailed information regarding rock wedge stability so that site monitoring and prevention plans can be conducted with higher efficiency.展开更多
[Objective]The aim was to study the distribution of Ca in bagged apple fruit and the relationship between antioxidant enzyme activity and bitter pit disease,which will provide a basis for resolving Ca metabolism disor...[Objective]The aim was to study the distribution of Ca in bagged apple fruit and the relationship between antioxidant enzyme activity and bitter pit disease,which will provide a basis for resolving Ca metabolism disorder in apple cultivation. [Method]With Fuji Apple as the tested material,the changes of Ca2＋ content and antioxidant enzyme activity in different parts of apple fruit after picking bags and storage period were determined. [Result]The results showed that Ca contents in the light surface of fruits were higher than that in the backlight surface. The Ca contents of stalk cavity were higher than that of calyx-end. The activities of SOD,POD,CAT and APX in the light surface of fruits were higher than that in the backlight surface. The activities of SOD,POD,CAT and APX of stalk cavity were higher than that of calyx-end. The contents of MDA in the light surface of fruits were lower than that in the backlight surface. The contents of MDA of stalk cavity were lower than that of calyx-end. [Conclusion]The incidence rate of bitter pit in the light surface of fruits were lower than that in the backlight surface,and the incidence rate of bitter pit of stalk cavity were lower than that of calyx-end.展开更多
The ecological costs of open pit metal mining are quantified, which include lost value of direct eco-services, lost value of indirect eco-services, prevention and restoration costs, and cost of carbon emission from en...The ecological costs of open pit metal mining are quantified, which include lost value of direct eco-services, lost value of indirect eco-services, prevention and restoration costs, and cost of carbon emission from energy consumption. These ecological costs are incorporated in an iterative ultimate pit optimization algorithm. A case study is presented to demonstrate the influence of ecological costs on pit design outcome. The results show that it is possible to internalize ecological costs in mine designs. The pit optimization outcome shifts considerably to the conservative side and the profitability decreases substantially when ecological costs are accounted for.展开更多
The pitting corrosion behaviors of 7A60 aluminum alloy in the retrogression and re-aging （RRA） temper were investigated by electrochemical impedance spectroscopy （EIS） and electrochemical noise （EN） techniques, ...The pitting corrosion behaviors of 7A60 aluminum alloy in the retrogression and re-aging （RRA） temper were investigated by electrochemical impedance spectroscopy （EIS） and electrochemical noise （EN） techniques, and the microstructure and the second phase content of the alloy were observed and determined by scanning electron microscopy （SEM） and energy dispersive spectrometer （EDS）. The results show that there exist two different corrosion stages for 7A60 alloy in 3.5%NaCl solution, and the corrosion process can be detected by the appearance of EIS spectrum with two capacitive time constants and the wavelet fractal dimension D extracted from EN. SEM and EDS results also demonstrate that severe pitting corrosion in 7A60 alloy is mainly caused by electrochemical active MgZn2 particles, secondly by Al2MgCu and Mg2Si. Al7Cu2Fe particles make little contribution to the pitting corrosion of 7A60 alloy.展开更多
基金supported by the National Natural Science Foundation of China(No.52074130)Engineering Research Center of Resource Utilization of Carbon-containing Waste with Carbon Neutrality,Ministry of Education,200237 Shanghai,PR China.
文摘To advance the understanding of the corrosion behavior of stainless steel bellows in marine atmospheric environments and enhance the precision of service life predictions,this study employs finite element simulations to investigate the pitting corrosion rates and pit morphologies of bellows peaks and troughs under varying electrolyte film thicknesses.The model incorporates localized electrochemical reactions,oxygen concentration,and homogeneous solution reactions.For improved computational accuracy,the fitted polarization curve data were directly applied as nonlinear boundary conditions on the electrode surface via interpolation functions.Simulation results reveal that the peak regions exhibit faster corrosion rates than the trough regions.With increasing electrolyte film thickness(from 10μm to 500μm),corrosion rates at both peaks and troughs decrease progressively,and after 120 hours of simulation,the maximum corrosion rate at the peaks declines from 0.720 mm/a to 0.130 mm/a,and at the troughs from 0.520 mm/a to 0.120 mm/a,with the disparity in corrosion rates diminishing over time.Furthermore,as corrosion progresses,pits propagate deeper into the substrate,exhibiting both vertical penetration and lateral expansion along the passive film interface,ultimately breaching the substrate.This research offers valuable insights into designing corrosion mitigation strategies for stainless steel bellows in marine environments.
基金Supported by Liaoning Province Science and Technology Research Project(2021JH1/10400011)National Natural Science Foundation of China(61971118).
文摘Background As information technology has advanced and been popularized,open pit mining has rapidly developed toward integration and digitization.The three-dimensional reconstruction technology has been successfully applied to geological reconstruction and modeling of surface scenes in open pit mines.However,an integrated modeling method for surface and underground mine sites has not been reported.Methods In this study,we propose an integrated modeling method for open pit mines that fuses a real scene on the surface with an underground geological model.Based on oblique photography,a real-scene model was established on the surface.Based on the surface-stitching method proposed,the upper and lower surfaces and sides of the model were constructed in stages to construct a complete underground three-dimensional geological model,and the aboveground and underground models were registered together to build an integrated open pit mine model.Results The oblique photography method used reconstructed a surface model of an open pit mine using a real scene.The surface-stitching algorithm proposed was compared with the ball-pivoting and Poisson algorithms,and the integrity of the reconstructed model was markedly superior to that of the other two reconstruction methods.In addition,the surface-stitching algorithm was applied to the reconstruction of different formation models and showed good stability and reconstruction efficiency.Finally,the aboveground and underground models were accurately fitted after registration to form an integrated model.Conclusions The proposed method can efficiently establish an integrated open pit model.Based on the integrated model,an open pit auxiliary planning system was designed and realized.It supports the functions of mining planning and output calculation,assists users in mining planning and operation management,and improves production efficiency and management levels.
基金founded by National Natural Science Foundations of China(Nos.52231003,52201084,and U21A20113)Major Program(JD)of Hubei Province(No.2023BAA019)+1 种基金Natural Science Foundation of Guangdong Province(No.2024A1515011022)Guangdong Province Basic and Applied Basic Research Fund Offshore Wind Power Joint Fund(No.2023B1515250006).
文摘The addition of vanadium substantially enhances the strength of the high-nitrogen austenitic stainless steel(HNASS),while maintaining excellent ductility and pitting corrosion resistance.The effects of vanadium microalloying on the microstructure,mechanical properties,and pitting resistance of HNASS were systematically analyzed with a focus on the role of VN during the pitting process.The results suggest that vanadium promoted the precipitation of VN,contributing to grain boundary pinning and grain refinement.As vanadium content increased,the number of precipitates rose,and the average grain size decreased.At lower vanadium content(0-0.2 wt.%),the strength of the material was significantly reinforced with increasing vanadium content,while maintaining excellent ductility and pitting resistance.However,when the vanadium content reached 0.3-0.4 wt.%,precipitates demonstrated a substantially increased number and coarsened,accompanied by the formation of numerous dislocations around the precipitates.This brought about further strength reinforcement but a marked decline in ductility and pitting resistance.Additionally,pitting corrosion was initiated at the matrix-VN interface.Compared to the matrix,VN exhibited higher reactivity and preferentially reacted with Cl−ions,provoking dissolution.However,NH4+generated during the dissolution of VN facilitated repassivation of the material,suppressing further pitting propagation.
基金supported by the National Natural Science Foundation of China(Nos.52364044 and 52204364)Central Guidance on Local Science and Technology Development Fund Projects of Inner Mongolia Autonomous Region(No.2022ZY0090)Basic Scientific Research Business Expenses of Colleges and Universities in Inner Mongolia Autonomous Region(Nos.2023QNJS011 and 0406082226).
文摘The micro-area characterization experiments like scanning Kelvin probe force microscope(SKPFM)and Kernel average misorientation have the defects of complex sample preparation and occasional errors in test results,which makes it impossible to accurately and quickly analyze the pitting behavior induced by inclusions in some cases,prompting attempts to turn to simulation calculation research.The method of calculating band structure and work function can be used to replace current-sensing atomic force microscopy and SKPFM to detect the potential and conductivity of the sample.The band structure results show that Al_(2)O_(3) inclusion is an insulator and non-conductive,and it will not form galvanic corrosion with the matrix.Al_(2)O_(3) inclusion does not dissolve because its work function is higher than that of the matrix.Moreover,the stress concentration of the matrix around the inclusion can be characterized by first-principles calculation coupled with finite element simulation.The results show that the stress concentration degree of the matrix around Al_(2)O_(3) inclusion is serious,and the galvanic corrosion is formed between the high and the low stress concentration areas,which can be used to explain the reason of the pitting induced by Al_(2)O_(3) inclusions.
基金supported by the Project of National Natural Science Foundation(82372206)the Project of Jiangsu Provincial Health Commission(H2023107)the Project of Basic and Clinical Research on Cardiac Arrest in the Emergency and Critical Care Department of the Second Affi liated Hospital of Soochow University(XKTJ-XK202408-2).
文摘Colorectal cancer is a common tumor of the digestive system and is the third leading cause of cancer-related death worldwide.The global incidence of colorectal cancer is currently increasing.In some patients,the tumor has already spread to nearby organs at the time of diagnosis,with the small intestine and bladder being common sites of invasion.[1,2]The diagnosis of colorectal cancer that has spread to the bladder can be challenging.Aside from a few patients who experience urinary symptoms due to invasion of the bladder trigone or the entire bladder wall,there are no distinct clinical signs,which often leads to misdiagnosis.The following case report details one such instance.
文摘The M-shaped multi-row pile foundation retaining structure represents an enhanced version of conventional multi-row anti-sliding support systems.To date,the implementation of M-shaped pile configurations in foundation pit excavations has not been extensively investigated,with particularly scant research focusing on their load-bearing mechanisms and stress redistribution characteristics.Furthermore,numerical modeling methodologies for such geometrically optimized pile networks remain underdeveloped compared to practical engineering applications,creating a notable research-practice gap in geotechnical engineering.A comparative finite element analysis was systematically conducted using ABAQUS software to establish three distinct excavation support configurations:single-row cantilever retaining structures,three-row cantilever configurations,and M-shaped multi-row pile foundation systems.Subsequent numerical simulations enabled quantitative comparisons of critical performance indicators,including pile stress distribution patterns,lateral displacement profiles,and bending moment diagrams across different structural typologies.The parametric investigation revealed characteristic mechanical responses associated with each configuration,establishing corresponding mechanical principles governing the interaction between pile topology and soil-structure behavior towers.The findings of this study provide critical references for the design optimization of M-shaped multi-row pile foundation retaining systems.
基金supported by the National Natural Science Foun-dation of China(Nos.U1908219,52171163)the Key Research Program of the Chinese Academy of Sciences(No.ZDRW-CN-2021-2-2)+1 种基金the Applied Basic Research Program of Liaoning Province(grant no.2022JH2/101300005)the Central Guidance for Local Science and Technology Development Funds of Liaoning Province(grant no.2023JH6/100100016).
文摘Precipitation-strengthened HEAs exhibit outstanding integration of strength and toughness at ambient temperature.Nevertheless,precipitates generally reduce the localized corrosion resistance in aggressive solution environments.To solve this problem,a strategy of introducing nano-sized L12 precipitates in CoCrFeNiAlTi HEAs has been proposed in this work.Results demonstrate the pitting corrosion potential can be elevated from 258 mVSCE to 603 mVSCE by increasing the precipitate content to 38 wt.%.Such an improvement in localized corrosion resistance can be attributed to two aspects.Firstly,L12 precipitates tend to be dissolved during the corrosion process,which promotes the heterogeneous nucleation of protective Cr2 O3 due to the rapid deposition of oxides/hydroxides of Al/Ti,and improves the passive film stability due to the Crrich FCC matrix.Secondly,the dissolution kinetic inside the pits can be suppressed on account of the enrichment of Cr element in the FCC matrix,thus inhibiting the pitting growth.In summary,the current work not only reveals the mechanisms of the nano-sized L12 precipitates upon the corrosion behavior,but also provides a strategy for designing corrosion-resistant HEA.
基金support from the National Natural Science Foundation of China(No.U22B2065)the Science&Technology Fundamental Resources Investigation Program(No.2022FY101300)+1 种基金the Guangdong Basic and Applied Basic Research Foundation,China(No.2023A1515110926)Fundamental Research Funds for Central Universities(No.FRF-TP-25-082).
文摘An effective approach to enhance the surface degradation characteristics of laser powder bed fusion(LPBF)type 420 stainless steel involves the incorporation of spherical cast WC/W_(2)C to create LPBF metal matrix composites(MMCs).However,the corrosion be-havior of stainless steel and cast WC/W_(2)C varies inversely across different pH levels,and the phenomenon of pitting corrosion in LPBF MMCs under varying pH conditions remains insufficiently explored.In LPBF 420+5wt%WC/W_(2)C MMCs,pits form adjacent to cast WC/W_(2)C in acidic and neutral environments,attributed to the presence of chromium-rich carbides and galvanic coupling effects.The dis-solution of the reinforced particles facilitates pit nucleation in alkaline conditions.Notably,in-situ reaction layers exhibit superior corro-sion resistance to the matrix or the reinforced particles across all pH levels.The distinct corrosion mechanisms influence the pitting corro-sion behavior,with the corrosion ranking based on critical pitting potential being neutral>alkaline>acidic,contrasting the observed kin-etics of pit growth(alkaline>acidic>neutral).
基金supported by the National Natural Science Foundation of China(No.52404354).
文摘Pitting corrosion poses a significant challenge to 9Cr18 high-carbon chromium bearing steel in chloride-rich environments,severely compromising its structural integrity.The study systematically investigates the pitting behaviour of 9Cr18 bearing steel under salt spray conditions,focusing on the progressive evolution of surface morphology and cross-sectional characteristics of pits on finished bearings.Scanning electron microscopy,energy-dispersive spectroscopy and X-ray diffraction were employed to examine the surface morphology,elemental composition and phase structure of corrosion products over varying salt spray exposure durations.The results show that 9Cr18 steel exhibits localized pitting with“volcanic crater”-like pits in the early stage of salt spray corrosion.After 48 h,pitting develops into a“multi-point”pattern,marking the initial transition toward uniform corrosion.Until 240 h,corrosion products completely cover the surface,indicating the complete transformation from localized pitting to uniform corrosion.The high carbon and chromium content in 9Cr18 steel promotes carbide precipitation and uneven distribution in the matrix.Cr-depleted regions near the carbide/matrix interface serve as preferential sites for pitting initiation.The low effective utilization of chromium reduces the overall corrosion resistance of 9Cr18.
文摘As one of the commonly used technologies in modern civil engineering,the construction technology is becoming more and more widely used with the continuous growth of building height.In the construction process of highrise buildings,the deep foundation pit support provides the necessary stability for the foundation structure of the building project,and more effectively guarantees the quality of the project.Through the reasonable supporting structure,the deep foundation pit technology can effectively prevent the risk of soil collapse,foundation pit deformation and other risks,and improve the safety factor of the whole construction project.Especially in the high-rise buildings,the deep foundation pit support technology can consolidate the foundation for the long-term stability of the project,and significantly prolong the service life of the building.The continuous development of deep foundation pit construction technology is the inevitable demand of high-rise building construction,and also provides a powerful help for the development of civil engineering industry.Based on this,this paper focuses on the application of deep foundation pit construction technology in civil engineering construction.
基金Kinross Gold and MITACS for their financial support(Grant No.FR42880).
文摘The goal of this research is to develop mine-scale discrete fracture network(DFN)models in which the influence of the spatial heterogeneity of fracture distributions may be investigated on the rock wedge stability of an open pit slope.For this purpose,spatially conditioned DFN models were developed for the pit walls at Tasiast mine using comprehensive structural data from the mine.Using Sequential Gaussian Simulation(SGS),volumetric fracture intensities(P32)were modeled across the entire mine site in the form of 3D block models.The simulated P32 block models were used as the input constraints for conditional DFN fracture generation,where the DFN grid dimension is the same as the SGS 3D blocks.The spatially constrained DFN models were further calibrated using aerial fracture intensities(P21)data from the pit walls,obtained by a survey of the pit walls using an unmanned aerial vehicle(UAV)and measured traces of joints from 3D point cloud data.The final DFN model is expected to honor the fracture intensities gathered through different means with optimal model accuracy.Finally,bench-scale and interramp scale rock wedge slope stability analyses were conducted using the calibrated conditional DFN models.This work proves the significance of conditioned DFN models in rock wedge stability analysis.Such models provide detailed information regarding rock wedge stability so that site monitoring and prevention plans can be conducted with higher efficiency.
基金Supported by National Natural Science Foundation Project " Relationship between Distribution of Calcium in Bagged Apple Fruit and Bitter Pit" (30871683)Education Department Project of Shandong Province (J06K56)~~
文摘[Objective]The aim was to study the distribution of Ca in bagged apple fruit and the relationship between antioxidant enzyme activity and bitter pit disease,which will provide a basis for resolving Ca metabolism disorder in apple cultivation. [Method]With Fuji Apple as the tested material,the changes of Ca2＋ content and antioxidant enzyme activity in different parts of apple fruit after picking bags and storage period were determined. [Result]The results showed that Ca contents in the light surface of fruits were higher than that in the backlight surface. The Ca contents of stalk cavity were higher than that of calyx-end. The activities of SOD,POD,CAT and APX in the light surface of fruits were higher than that in the backlight surface. The activities of SOD,POD,CAT and APX of stalk cavity were higher than that of calyx-end. The contents of MDA in the light surface of fruits were lower than that in the backlight surface. The contents of MDA of stalk cavity were lower than that of calyx-end. [Conclusion]The incidence rate of bitter pit in the light surface of fruits were lower than that in the backlight surface,and the incidence rate of bitter pit of stalk cavity were lower than that of calyx-end.
基金Project(50974041)supported by the National Natural Science Foundation of ChinaProject(NCET-11-0073)supported by Program for New Century Excellent Talents in University of Ministry of Education of China+1 种基金Project(201102065)supported by the Natural Science Foundation of Liaoning Province,ChinaProject(2012921075)supported by the Ten Million Talent Project of Liaoning Province,China
文摘The ecological costs of open pit metal mining are quantified, which include lost value of direct eco-services, lost value of indirect eco-services, prevention and restoration costs, and cost of carbon emission from energy consumption. These ecological costs are incorporated in an iterative ultimate pit optimization algorithm. A case study is presented to demonstrate the influence of ecological costs on pit design outcome. The results show that it is possible to internalize ecological costs in mine designs. The pit optimization outcome shifts considerably to the conservative side and the profitability decreases substantially when ecological costs are accounted for.
基金Project(13JCZDJC29500)supported by the Key Project of Tianjin Natural Science Foundation,ChinaProjects(2011CB610505,2014CB046801)supported by the National Basic Research Program of ChinaProject(20120032110029)supported by the Specialized Research Fund for the Doctoral Program of Higher Education,China
文摘The pitting corrosion behaviors of 7A60 aluminum alloy in the retrogression and re-aging （RRA） temper were investigated by electrochemical impedance spectroscopy （EIS） and electrochemical noise （EN） techniques, and the microstructure and the second phase content of the alloy were observed and determined by scanning electron microscopy （SEM） and energy dispersive spectrometer （EDS）. The results show that there exist two different corrosion stages for 7A60 alloy in 3.5%NaCl solution, and the corrosion process can be detected by the appearance of EIS spectrum with two capacitive time constants and the wavelet fractal dimension D extracted from EN. SEM and EDS results also demonstrate that severe pitting corrosion in 7A60 alloy is mainly caused by electrochemical active MgZn2 particles, secondly by Al2MgCu and Mg2Si. Al7Cu2Fe particles make little contribution to the pitting corrosion of 7A60 alloy.
