In this article,computational fluid dynamics(CFD)are used to explore the dynamics of water transport inside the pitted thickening of a plant xylem vessel.A pitted thickening model combined with the Bernoulli equation ...In this article,computational fluid dynamics(CFD)are used to explore the dynamics of water transport inside the pitted thickening of a plant xylem vessel.A pitted thickening model combined with the Bernoulli equation is used to analyze the influence of various factors(namely,the inner diameter,thickening width,thickening height,thickening spacing,number of laps and adjacent pit axial rotation).The pressure drop and the flow resistance coefficient are the variable parameters for our analysis.The results show that these two parameters are proportional to the thickening height and thickening width,and inversely proportional to the inner diameter,thickening spacing and number of laps.Three different wall thickening structures of the vessel are compared and the pitted thickening vessel is shown to provide the largest structural flow resistance,the annular thickening vessel has the second largest resistance and the helical thickening vessel corresponds to the smallest resistance of the three structures.展开更多
Pitted cones are cone-shaped structures,spanning from meters to kilometers in size,characterized by summit depressions.They are widely distributed on the surface of Mars with various origins,such as rootless cones,mud...Pitted cones are cone-shaped structures,spanning from meters to kilometers in size,characterized by summit depressions.They are widely distributed on the surface of Mars with various origins,such as rootless cones,mud volcanoes,cinder or scoria cones,tuff rings or cones,pingos,and dirt cones.If the pitted cones identified in southern Utopia Planitia are mud volcanoes,as is speculated,they could be of particular interest due to the fact that mud volcanoes on Earth bring sediments from a depth of meters to kilometers to the surface.In this study,we have investigated the pitted cones near Zhurong rover’s landing site in southern Utopia Planitia,utilizing recent images and digital elevation models obtained from the High Resolution Imaging Camera instrument onboard China’s Tianwen-1 orbiter.By leveraging the high-resolution images and digital elevation models,we have conducted a geometric measurement to distinguish the origin of pitted cones in the vicinity of the Zhurong rover.The morphological characteristics of these pitted cones indicate an explosive mud volcano origin.These explosive mud volcanoes could have formed by the violent eruption of subsurface overpressurized sediments generated from the combined effect of overburden pressure and anomalous high heat flow.The sediments forming the pitted cones in the northern plains could be the remnants of an ancient ocean.With future in-situ observations of these pitted cones,we hope to gain further insights into the sediments of the putative northern ocean,as well as the physical and chemical properties of the Martian subsurface during the formation of the pitted cones.展开更多
Bitter Pit(BP)is a prevalent physiological disorder in apple that significantly reduces fruit quality and market value.While numerous studies have investigated the mechanisms underlying BP occurrence,the molecular pro...Bitter Pit(BP)is a prevalent physiological disorder in apple that significantly reduces fruit quality and market value.While numerous studies have investigated the mechanisms underlying BP occurrence,the molecular processes,particularly the role of the Ca^(2+)/H^(+)exchanger(CAX),remain unclear.This study aims to elucidate the function of the MdCAX5 gene in relation to BP development.To achieve this,we utilized transient transformation in apple,as well as stable transformation in Arabidopsis and tomato,to measure the mineral content in transgenic plants,thereby validating the function of MdCAX5.The overexpression of the MdCAX5 gene significantly reduced calcium(Ca)content in plants and disrupted the mineral element balance within the plant.Analysis of the MdCAX5 gene promoter revealed that Ca^(2+)can enhance promoter activity,indicating that the MdCAX5 gene can effectively respond to Ca signaling.Transcriptomic analysis of tomato plants stably overexpressing the MdCAX5 gene revealed significant alterations in the expression of genes involved in Ca signal transduction and transport,which in turn impacted the biosynthesis of secondary metabolites and metabolic pathways within the plants.These changes resulted in a reduction in Ca content,imbalanced Ca distribution,increased hydrolase activity,and disrupted cellular structures,including compromised organelles,cellular membranes,and membrane components.These disruptions culminated in the manifestation of Ca deficiency symptoms in the plants.This study provides theoretical insights into the mechanisms underlying the occurrence of apple BP disease.展开更多
Lutetium oxide(Lu_(2)O_(3))is recognized as a potential laser crystal material,and it is noted for its high ther⁃mal conductivity,low phonon energy,and strong crystal field.Nevertheless,its high melting point of 2450...Lutetium oxide(Lu_(2)O_(3))is recognized as a potential laser crystal material,and it is noted for its high ther⁃mal conductivity,low phonon energy,and strong crystal field.Nevertheless,its high melting point of 2450℃induces significant temperature gradients,resulting in a proliferation of defects.The scarcity of comprehensive research on this crystal’s defects hinders the enhancement of crystal quality.In this study,we employed the chemical etching method to examine the etching effects on Lu_(2)O_(3)crystals under various conditions and to identify the optimal conditions for investi⁃gating the dislocation defects of Lu_(2)O_(3)crystals(mass fraction 70%H3PO4,160℃,15-18 min).The morphologies of dislocation etch pits on the(111)-and(110)-oriented Lu_(2)O_(3)wafers were characterized using microscopy,scanning electron microscopy and atomic force microscopy.This research addresses the gap in understanding Lu_(2)O_(3)line defects and offers guidance for optimizing the crystal growth process and improving crystal quality.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 corrosion behavior of deposit-covered aluminum alloy 7075(AA7075)caused by fungus Aspergillus terreus(A.terreus)was thoroughly investigated in artificial seawater aiming to offer some new insights into the under-d...The corrosion behavior of deposit-covered aluminum alloy 7075(AA7075)caused by fungus Aspergillus terreus(A.terreus)was thoroughly investigated in artificial seawater aiming to offer some new insights into the under-deposit corrosion mechanism of aluminum alloys in marine environments containing fungi.Electrochemical impedance spectroscopy,polarization curves,wire beam electrodes,and surface analysis were performed.Results indicate that A.terreus can survive beneath the deposit but the counts of sessile spores decline as the increase of deposit thickness,suggesting a poor biological activity of A.terreus beneath the deposit.Both the uniform corrosion and pitting corrosion are accelerated by A.terreus,while the pitting corrosion of AA7075 alloys beneath the deposit derives from a galvanic cell with a small anode and a large cathode.Deposits have a corrosion inhibition effect on AA7075.However,the galvanic effect caused by the bare and deposit-covered AA specimens is obviously enhanced by A.terreus.展开更多
The transformation mechanism of the inclusions and microstructure in 316L stainless steel after post-isothermal heat treatment(IHT)was revealed,along with the pitting behavior of the inclusions in a chloride environme...The transformation mechanism of the inclusions and microstructure in 316L stainless steel after post-isothermal heat treatment(IHT)was revealed,along with the pitting behavior of the inclusions in a chloride environment before and after the transformation.The effect of the inclusion transformation on the pitting corrosion behavior of 316L stainless steel and its intrinsic mechanism was also revealed.Results revealed a gradual transformation of MnO-SiO_(2)inclusions into MnO-Cr_(2)O_(3) within the temperature range of 1373 to 1573 K.MnO-Cr_(2)O_(3)inclusions exhibited minimal dissolution in chloride ion corrosion environments,while MnO-SiO_(2)oxides demonstrated higher electrochemical activity and were more prone to dissolve and form pits.Meanwhile,IHT significantly reduced the dislocation density of stainless steel,rendering it more stable in corrosive environments.X-ray photoelectron spectroscopy peak distributions of the passive films demonstrated that IHT increased the proportion of Cr and Fe oxides and hydroxides in the passive film which improved the stability and corrosion resistance of the steel.展开更多
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
By employing micrometer-diameter microelectrodes, the metastable pitting corrosion behavior of Co_(68.15)Fe_(4.35)Si_(12.5)B_(12)Cr_(3) metallic glasses (MGs) exposed to 0.6 mol/L NaCl solution was investigated to cla...By employing micrometer-diameter microelectrodes, the metastable pitting corrosion behavior of Co_(68.15)Fe_(4.35)Si_(12.5)B_(12)Cr_(3) metallic glasses (MGs) exposed to 0.6 mol/L NaCl solution was investigated to clarify the correlation between metastable pitting and structural heterogeneity in MGs. Thermally induced degeneration of structural heterogeneity inhibits the initiation, decelerates the growth kinetics, and accelerates the repassivation kinetics of metastable pits while also decreasing the probability of transition from metastability to stability. This enhanced resistance to pitting corrosion is attributed to a reduction in active pitting precursor sites and a decrease in electrochemical activity caused by the structural homogenization of MGs.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
In this study,the pure erosion behaviour of pure iron and its erosion-corrosion behaviour under different anodic polarization currents were investigated in various cathodic reactions(oxygen reduction,hydrogen ion redu...In this study,the pure erosion behaviour of pure iron and its erosion-corrosion behaviour under different anodic polarization currents were investigated in various cathodic reactions(oxygen reduction,hydrogen ion reduction,and water reduction)using a cylindrical stirring system.The corrosion-enhanced erosion(C-E)rates were determined for each condition.The results revealed that pure iron displayed similar pure erosion behaviour across all three cathodic reactions.When the cathodic reactions involve hydrogen ion reduction or water reduction,the erosion-corrosion of pure iron manifested as uniform damage,with the reduction in hardness being the main cause of the C-E in this case.Conversely,in the case of oxy-gen reduction reaction as the cathodic reaction,the erosion-corrosion presented as pitting damage,with the reduction in hardness resulting from localized concentration of anodic current and the formation of easily worn protruding flaky iron structures at the edges of the pits as the main mechanism of the C-E.Moreover,linear and exponential relationships were found between the C-E rate and the anodic current density for uniform damage and pitting damage,respectively.Finally,the concept of surface equivalent hardness was proposed,along with the establishment of a mathematical model for surface equivalent hardness based on the relationships between the C-E rate and the anodic current density.Utilizing the surface equivalent hardness enables the evaluation of the erosion rate on material surfaces considering the coupled effect.展开更多
In this work,the effect of high angle grain boundaries(HAGBs),including prior austenite grain boundaries(PAGB),packet grain boundaries(PGB)and block grain boundaries(BGB),on the priority of pitting and microcrack init...In this work,the effect of high angle grain boundaries(HAGBs),including prior austenite grain boundaries(PAGB),packet grain boundaries(PGB)and block grain boundaries(BGB),on the priority of pitting and microcrack initiation for 10Cr13Co13Mo5Ni3W1VE ultra-high strength stainless steel(UHSS)has been clarified.PAGB had the highest carbide distribution coefficient and was the main location where pitting preferentially initiated for the UHSS in 3.5 wt.%NaCl solution without strain.It was shown that nanocarbides were the key factor of pitting initiation for the UHSS without strain.However,BGB was the key factor of pitting/microcrack initiation for the UHSS with strain,which was attributed to the high-density dislocations accumulated at BGB and then enhanced the local electrochemical activity of the UHSS surface.The change of the key factor for the pitting initiation in the UHSS was the result of the synergy between strain and corrosion environment.This study provides guidance for designing advanced UHSS with high service stability and safety.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
Reinforcing bars in concrete structures in marine environment are prone to pitting corrosion,which threatens the safety of engineering structures.In order to effectively mitigate the pitting corrosion of reinforcing b...Reinforcing bars in concrete structures in marine environment are prone to pitting corrosion,which threatens the safety of engineering structures.In order to effectively mitigate the pitting corrosion of reinforcing bars,the electrochemical testing and atomic force microscopy are adopted,the effect of triethanolamine dodecylbenzene sulfonate(TDS)on metastable pitting behavior of 304 stainless steel(304 SS)in simulated concrete pore solutions(SCPS)with chlorine contamination was studied.The results show that the corrosion potential(Ecorr)and breakdown potential(Eb)increased with the growth of the TDS concentrations.Statistical cha-racteristics of metastable pits suggested that as the TDS concentrations increased in the SCPS,the parameters were all decreased.The Mott-Schottky tests exhibited that,although the donor density(ND)diminished,the thickness of the space charge layer(W)increased with increasing TDS concentrations.Investigation results showed that TDS inhibited the sprouting and growth of metastable pits,and with greater TDS concentration,it becomes more difficult for metastable pits to transfer into stable pits in the SCPS,the generated stable passive film prevented the sprouting of pitting corrosion,It is recommended to use TDS with a concentration of not less than 3.364×10^(-4) mol/L in engineering,so that the sensitivity of passivation film of 304SS to chloride erosion is reduced.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51279071,51969009)the Foundation of the Ministry of Education of China for Ph.D candidates in University(Grant No.2013531413002).
文摘In this article,computational fluid dynamics(CFD)are used to explore the dynamics of water transport inside the pitted thickening of a plant xylem vessel.A pitted thickening model combined with the Bernoulli equation is used to analyze the influence of various factors(namely,the inner diameter,thickening width,thickening height,thickening spacing,number of laps and adjacent pit axial rotation).The pressure drop and the flow resistance coefficient are the variable parameters for our analysis.The results show that these two parameters are proportional to the thickening height and thickening width,and inversely proportional to the inner diameter,thickening spacing and number of laps.Three different wall thickening structures of the vessel are compared and the pitted thickening vessel is shown to provide the largest structural flow resistance,the annular thickening vessel has the second largest resistance and the helical thickening vessel corresponds to the smallest resistance of the three structures.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB 41000000)the National Natural Science Foundation of China(Grant Nos.42273041,42272274,41830214)the Pre-research Project on Civil Aerospace Technologies of CNSA(Grant No.D020101).
文摘Pitted cones are cone-shaped structures,spanning from meters to kilometers in size,characterized by summit depressions.They are widely distributed on the surface of Mars with various origins,such as rootless cones,mud volcanoes,cinder or scoria cones,tuff rings or cones,pingos,and dirt cones.If the pitted cones identified in southern Utopia Planitia are mud volcanoes,as is speculated,they could be of particular interest due to the fact that mud volcanoes on Earth bring sediments from a depth of meters to kilometers to the surface.In this study,we have investigated the pitted cones near Zhurong rover’s landing site in southern Utopia Planitia,utilizing recent images and digital elevation models obtained from the High Resolution Imaging Camera instrument onboard China’s Tianwen-1 orbiter.By leveraging the high-resolution images and digital elevation models,we have conducted a geometric measurement to distinguish the origin of pitted cones in the vicinity of the Zhurong rover.The morphological characteristics of these pitted cones indicate an explosive mud volcano origin.These explosive mud volcanoes could have formed by the violent eruption of subsurface overpressurized sediments generated from the combined effect of overburden pressure and anomalous high heat flow.The sediments forming the pitted cones in the northern plains could be the remnants of an ancient ocean.With future in-situ observations of these pitted cones,we hope to gain further insights into the sediments of the putative northern ocean,as well as the physical and chemical properties of the Martian subsurface during the formation of the pitted cones.
基金funded by National Natural Science Foundation of China(Grant No.32300327).
文摘Bitter Pit(BP)is a prevalent physiological disorder in apple that significantly reduces fruit quality and market value.While numerous studies have investigated the mechanisms underlying BP occurrence,the molecular processes,particularly the role of the Ca^(2+)/H^(+)exchanger(CAX),remain unclear.This study aims to elucidate the function of the MdCAX5 gene in relation to BP development.To achieve this,we utilized transient transformation in apple,as well as stable transformation in Arabidopsis and tomato,to measure the mineral content in transgenic plants,thereby validating the function of MdCAX5.The overexpression of the MdCAX5 gene significantly reduced calcium(Ca)content in plants and disrupted the mineral element balance within the plant.Analysis of the MdCAX5 gene promoter revealed that Ca^(2+)can enhance promoter activity,indicating that the MdCAX5 gene can effectively respond to Ca signaling.Transcriptomic analysis of tomato plants stably overexpressing the MdCAX5 gene revealed significant alterations in the expression of genes involved in Ca signal transduction and transport,which in turn impacted the biosynthesis of secondary metabolites and metabolic pathways within the plants.These changes resulted in a reduction in Ca content,imbalanced Ca distribution,increased hydrolase activity,and disrupted cellular structures,including compromised organelles,cellular membranes,and membrane components.These disruptions culminated in the manifestation of Ca deficiency symptoms in the plants.This study provides theoretical insights into the mechanisms underlying the occurrence of apple BP disease.
基金Supported by National Key Research and Development Program of China(2021YFB3601403)National Natural Science Foundation of China(62105181)Taishan Scholar of Shandong Province(tsqn202306014)。
文摘Lutetium oxide(Lu_(2)O_(3))is recognized as a potential laser crystal material,and it is noted for its high ther⁃mal conductivity,low phonon energy,and strong crystal field.Nevertheless,its high melting point of 2450℃induces significant temperature gradients,resulting in a proliferation of defects.The scarcity of comprehensive research on this crystal’s defects hinders the enhancement of crystal quality.In this study,we employed the chemical etching method to examine the etching effects on Lu_(2)O_(3)crystals under various conditions and to identify the optimal conditions for investi⁃gating the dislocation defects of Lu_(2)O_(3)crystals(mass fraction 70%H3PO4,160℃,15-18 min).The morphologies of dislocation etch pits on the(111)-and(110)-oriented Lu_(2)O_(3)wafers were characterized using microscopy,scanning electron microscopy and atomic force microscopy.This research addresses the gap in understanding Lu_(2)O_(3)line defects and offers guidance for optimizing the crystal growth process and improving crystal quality.
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 Guangdong Basic and Applied Basic Research Foundation,China(No.2023A1515012146)the National Natural Science Foundation of China(No.52271083).
文摘The corrosion behavior of deposit-covered aluminum alloy 7075(AA7075)caused by fungus Aspergillus terreus(A.terreus)was thoroughly investigated in artificial seawater aiming to offer some new insights into the under-deposit corrosion mechanism of aluminum alloys in marine environments containing fungi.Electrochemical impedance spectroscopy,polarization curves,wire beam electrodes,and surface analysis were performed.Results indicate that A.terreus can survive beneath the deposit but the counts of sessile spores decline as the increase of deposit thickness,suggesting a poor biological activity of A.terreus beneath the deposit.Both the uniform corrosion and pitting corrosion are accelerated by A.terreus,while the pitting corrosion of AA7075 alloys beneath the deposit derives from a galvanic cell with a small anode and a large cathode.Deposits have a corrosion inhibition effect on AA7075.However,the galvanic effect caused by the bare and deposit-covered AA specimens is obviously enhanced by A.terreus.
基金the support from the National Natural Science Foundation of China(Grant Nos.52074198,52374342,and U21A20113)the Department of Science and Technology of Hubei Province(Grant Nos.2023AFB603 and 2023DJC140).
文摘The transformation mechanism of the inclusions and microstructure in 316L stainless steel after post-isothermal heat treatment(IHT)was revealed,along with the pitting behavior of the inclusions in a chloride environment before and after the transformation.The effect of the inclusion transformation on the pitting corrosion behavior of 316L stainless steel and its intrinsic mechanism was also revealed.Results revealed a gradual transformation of MnO-SiO_(2)inclusions into MnO-Cr_(2)O_(3) within the temperature range of 1373 to 1573 K.MnO-Cr_(2)O_(3)inclusions exhibited minimal dissolution in chloride ion corrosion environments,while MnO-SiO_(2)oxides demonstrated higher electrochemical activity and were more prone to dissolve and form pits.Meanwhile,IHT significantly reduced the dislocation density of stainless steel,rendering it more stable in corrosive environments.X-ray photoelectron spectroscopy peak distributions of the passive films demonstrated that IHT increased the proportion of Cr and Fe oxides and hydroxides in the passive film which improved the stability and corrosion resistance of the steel.
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 the National Natural Science Foun-dation of China(No.52401222)Zhejiang Provincial Natural Sci-ence Foundation(LQN25E010011)+2 种基金Ningbo Natural Science Founda-tion(2024J073)Ningbo Major Special Projects of the Plan“Science and Technology Innovation 2025"(No.2022Z107)Ningbo Key Research and Development Program(No.2023Z097).
文摘By employing micrometer-diameter microelectrodes, the metastable pitting corrosion behavior of Co_(68.15)Fe_(4.35)Si_(12.5)B_(12)Cr_(3) metallic glasses (MGs) exposed to 0.6 mol/L NaCl solution was investigated to clarify the correlation between metastable pitting and structural heterogeneity in MGs. Thermally induced degeneration of structural heterogeneity inhibits the initiation, decelerates the growth kinetics, and accelerates the repassivation kinetics of metastable pits while also decreasing the probability of transition from metastability to stability. This enhanced resistance to pitting corrosion is attributed to a reduction in active pitting precursor sites and a decrease in electrochemical activity caused by the structural homogenization of MGs.
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supported by the National Key Research and Development Program(No.2022YFC2806200)the National Key Research and Development Program(No.2023YFC2810800)the Natural Science Foundation of China(No.52001055).
文摘In this study,the pure erosion behaviour of pure iron and its erosion-corrosion behaviour under different anodic polarization currents were investigated in various cathodic reactions(oxygen reduction,hydrogen ion reduction,and water reduction)using a cylindrical stirring system.The corrosion-enhanced erosion(C-E)rates were determined for each condition.The results revealed that pure iron displayed similar pure erosion behaviour across all three cathodic reactions.When the cathodic reactions involve hydrogen ion reduction or water reduction,the erosion-corrosion of pure iron manifested as uniform damage,with the reduction in hardness being the main cause of the C-E in this case.Conversely,in the case of oxy-gen reduction reaction as the cathodic reaction,the erosion-corrosion presented as pitting damage,with the reduction in hardness resulting from localized concentration of anodic current and the formation of easily worn protruding flaky iron structures at the edges of the pits as the main mechanism of the C-E.Moreover,linear and exponential relationships were found between the C-E rate and the anodic current density for uniform damage and pitting damage,respectively.Finally,the concept of surface equivalent hardness was proposed,along with the establishment of a mathematical model for surface equivalent hardness based on the relationships between the C-E rate and the anodic current density.Utilizing the surface equivalent hardness enables the evaluation of the erosion rate on material surfaces considering the coupled effect.
文摘In this work,the effect of high angle grain boundaries(HAGBs),including prior austenite grain boundaries(PAGB),packet grain boundaries(PGB)and block grain boundaries(BGB),on the priority of pitting and microcrack initiation for 10Cr13Co13Mo5Ni3W1VE ultra-high strength stainless steel(UHSS)has been clarified.PAGB had the highest carbide distribution coefficient and was the main location where pitting preferentially initiated for the UHSS in 3.5 wt.%NaCl solution without strain.It was shown that nanocarbides were the key factor of pitting initiation for the UHSS without strain.However,BGB was the key factor of pitting/microcrack initiation for the UHSS with strain,which was attributed to the high-density dislocations accumulated at BGB and then enhanced the local electrochemical activity of the UHSS surface.The change of the key factor for the pitting initiation in the UHSS was the result of the synergy between strain and corrosion environment.This study provides guidance for designing advanced UHSS with high service stability and safety.
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supports from the National Natural Science Foundation of China(Nos.51509081,52208241).
文摘Reinforcing bars in concrete structures in marine environment are prone to pitting corrosion,which threatens the safety of engineering structures.In order to effectively mitigate the pitting corrosion of reinforcing bars,the electrochemical testing and atomic force microscopy are adopted,the effect of triethanolamine dodecylbenzene sulfonate(TDS)on metastable pitting behavior of 304 stainless steel(304 SS)in simulated concrete pore solutions(SCPS)with chlorine contamination was studied.The results show that the corrosion potential(Ecorr)and breakdown potential(Eb)increased with the growth of the TDS concentrations.Statistical cha-racteristics of metastable pits suggested that as the TDS concentrations increased in the SCPS,the parameters were all decreased.The Mott-Schottky tests exhibited that,although the donor density(ND)diminished,the thickness of the space charge layer(W)increased with increasing TDS concentrations.Investigation results showed that TDS inhibited the sprouting and growth of metastable pits,and with greater TDS concentration,it becomes more difficult for metastable pits to transfer into stable pits in the SCPS,the generated stable passive film prevented the sprouting of pitting corrosion,It is recommended to use TDS with a concentration of not less than 3.364×10^(-4) mol/L in engineering,so that the sensitivity of passivation film of 304SS to chloride erosion is reduced.
