It was found that the steel plate in the composite plate in the WJ-8 fastener used in high speed rail is rusty. The objective of this study is to test the zinc coating of the steel plate. A literature review was condu...It was found that the steel plate in the composite plate in the WJ-8 fastener used in high speed rail is rusty. The objective of this study is to test the zinc coating of the steel plate. A literature review was conducted to identify the zinc coating techniques, and the companies that can provide different coating service was identified. A salt fog chamber was built that was in compliance with the ANSI B117 code, and the steel plates that were coated by the identified companies were tested using the salt fog chamber. The results indicated that the coating technique that had the best performance in preventing corrosion was the Greenkote plates with passivation. The galvanized option had the roughest coating layer, and it was the most reactive in the salt water solution. This makes it non-ideal for the dynamic rail environment because the increased friction of the plate could damage the supports, especially during extreme temperatures that would cause the rail to expand or contract. Greenkote with Phosphate and ArmorGalv also provided increased corrosion prevention with a smooth, strong finish, but it had more rust on the surface area than the Greenkote with ELU passivation. The ArmorGalv sample had more rust on the surface area than the Greenkote samples. This may not be a weakness in the ArmorGalv process;rather, it likely was the result of this particular sample not having the added protection of a colored coating.展开更多
This work is devoted to the study of the inhibition of corrosion of mild steel(MS)in molar hydrochloric acid(1 mol·L-1 HCl)by two named quinoxaline derivatives namely,2-(2,4-dichlorophenyl)-1,4-dihydroquinoxaline...This work is devoted to the study of the inhibition of corrosion of mild steel(MS)in molar hydrochloric acid(1 mol·L-1 HCl)by two named quinoxaline derivatives namely,2-(2,4-dichlorophenyl)-1,4-dihydroquinoxaline(HQ)and 2-(2,4-dichlorophenyl)-6-methyl-1,4-dihydroquinoxaline(CQ).The inhibitory efficacy of HQ and CQ compounds is first evaluated using the gravimetric method and using electrochemical techniques(stationary and transient techniques).The results showed that our compounds are efficient corrosion inhibitors and the inhibition rates(ηEIS%)reached up to 91%and 94.2%at 10-3 mol·L-1 for HQ and CQ,respectively.The mentioned molecules are classified as mixed-type inhibitors.The adsorption of these inhibitors on the surface of steel in hydrochloric HCl 1 mol·L-1 medium obeys the Langmuir adsorption isotherm.The results of the scanning electron microscope(SEM)showed the formation of a protective film on the surface of the steel in the presence of the inhibitors studied.Elementary analysis is obtained by energy dispersive X-ray spectroscopy(EDS).The inhibition property was further elucidated by theoretical approaches such as:Density Functional Theory(DFT),quantum chemical descriptors(QCD),local reactive indices,solvent effect,theoretical complexation,Molecular Dynamic(MD)simulation,effect of temperature on adsorption energy(Eads),Radial Distribution Function(RDF),and Mean Square Displacement(MSD).The results of these approaches support the experimental results.展开更多
To study the behavior of coral aggregate concrete(CAC)column under axial and eccentric compression,the compression behavior of CAC column with different types of steel and initial eccentricity(ei)were tested,and the d...To study the behavior of coral aggregate concrete(CAC)column under axial and eccentric compression,the compression behavior of CAC column with different types of steel and initial eccentricity(ei)were tested,and the deformation behavior and ultimate bearing capacity(Nu)were studied.The results showed that as the ei increases,the Nu of CAC column decreases nonlinearly.Besides,the steel corrosion in CAC column is severe,which reduces the steel section and steel strength,and decreases the Nu of CAC column.The durability of CAC structures can be improved by using new organic coated steel.Considering the influence of steel corrosion and interfacial bond deterioration,the calculation models of Nu under axial and eccentric compression were presented.展开更多
The corrosion behavior of corrosion resistant steel(CRS) in a simulated wet–dry acid humid environment was investigated and compared with carbon steel(CS) using corrosion loss, polarization curves, X-ray diffraction(...The corrosion behavior of corrosion resistant steel(CRS) in a simulated wet–dry acid humid environment was investigated and compared with carbon steel(CS) using corrosion loss, polarization curves, X-ray diffraction(XRD), scanning electron microscopy(SEM), electron probe micro-analysis(EPMA), N_2 adsorption, and X-ray photoelectron spectroscopy(XPS). The results show that the corrosion kinetics of both steels were closely related to the composition and compactness of the rust, and the electrochemical properties of rusted steel. Small amounts of Cu, Cr, and Ni in CRS increased the amount of amorphous phases and decreased the content of γ-Fe OOH in the rust, resulting in higher compactness and electrochemical stability of the CRS rust. The elements Cu, Cr, and Ni were uniformly distributed in the CRS rust and formed CuFeO_2, Cu_2O, CrOOH, NiFe_2O_4, and Ni_2O_3, which enhanced the corrosion resistance of CRS in the wet–dry acid humid environment.展开更多
Electrochemical techniques of the corrosion measurements of reinforcing steeI in concrete have been evaluated. These techniques include half-cell potential measurements, impressed voltage method, impressed current met...Electrochemical techniques of the corrosion measurements of reinforcing steeI in concrete have been evaluated. These techniques include half-cell potential measurements, impressed voltage method, impressed current method and potentiostatic polarization technique. The results of corrosion behaviour of the steel in both 5%NaCl and 5%MgSO4 show that each electrochemical technique provides some information about the condition of the steel bar or the corrosivity of the environment being evaluated, yet none provides a complete data regarding the corrosion resistance of reinforcing steel in aggressive展开更多
Corrosion and electrochemical behaviour of reinforcing steel embedded in cement pastes with and without concrete admixtures used in Egypt to modify concrete properties have been studied. The influence of the admixture...Corrosion and electrochemical behaviour of reinforcing steel embedded in cement pastes with and without concrete admixtures used in Egypt to modify concrete properties have been studied. The influence of the admixtures on the corrosion resistance of the steel against chloride attack has been studied using impressed current and impressed voltage techniques. The results indicate that the type and concentration of the admixture used have an important effed on the extent of chloride induced corrosion of the steel. The mechanism of corrosion of steel due to chloride attack is discussed.展开更多
High-temperature tensile tests were conducted for high corrosion resistant weathering steel S450EW.The morphologies of fracture microstructures,dislocations and precipitates were investigated by field emission scannin...High-temperature tensile tests were conducted for high corrosion resistant weathering steel S450EW.The morphologies of fracture microstructures,dislocations and precipitates were investigated by field emission scanning electron microscopy and transmission electron microscopy.The high-temperature plastic deformation behavior and brittle mechanism of S450EW steel were also studied.The experimental results show that the ductility troughs appear at 700-850℃ and 650-900℃ when the strain rates are 3×10^(-3)and 1.5×10^(-2)s^(-1),respectively.With the increase of strain rates,the ductility trough moves to the lower temperature side.The hot ductility is best when the cooling rate is 5℃/s before deformation at 750℃and the area reduction rate reaches 60.56%.Fine second phase particles and inclusions precipitated before and during deformation provide effective core positions for microcracks or microvoids formation during deformation process.It is also easy to cause stress concentration which results in microcracks or microvoids between grains during deformation and ultimately causes damage along the grain boundaries.The precipitated particles inhibit austenite dynamic recrystallization and therefore enhance intergranular fracture along austenite grain boundaries.The deformation induced proeutectoid ferrite films distribute along the austenite grain boundaries hinder the dynamic recrystallization.The deformation concentrated on network ferrite films produces damage of grain boundaries.展开更多
To investigate the effectiveness of self-made zinc alloy sacrificial anode material for the protection of reinforcement in concrete under chlorine salt erosion environment,salt solution immersion corrosion and electro...To investigate the effectiveness of self-made zinc alloy sacrificial anode material for the protection of reinforcement in concrete under chlorine salt erosion environment,salt solution immersion corrosion and electromigration accelerated corrosion tests were used to evaluate the effectiveness of self-made zinc alloy anode with the help of relevant cathodic protection guidelines and evaluation criteria for the corrosion of reinforcement in concrete.The results showed that the protection was effective because the potential of the zinc alloy anode protection steel bar in the salt solution satis?ed the“-780 mV(SCE)”validity criterion.The self-corrosion potential(E_(corr))of the sacri?cial anode protection steel in concrete was greater than-276 mV,and the protective current density of the zinc alloy anode was 1-3μA·cm^(-2),which met the standards of EN12696-2000,further indicating that the self-made zinc alloy sacri?cial anode had a good protection combining with the polarization resistance and the appearance of the corroded surface of the steel in concrete.The microscopic morphology of the corroded surface and the composition of the corrosion products indicates that the mortar of the self-made zinc alloy anode has a lower pH than the imported anodes,so the long-term protection of the selfmade zinc alloy sacri?cial anode needs to be further improved.展开更多
In this study,a total of 177 flexural experimental tests of corroded reinforced concrete(CRC)beams were collected from the published literature.The database of flexural capacity of CRC beam was established by using un...In this study,a total of 177 flexural experimental tests of corroded reinforced concrete(CRC)beams were collected from the published literature.The database of flexural capacity of CRC beam was established by using unified and standardized experimental data.Through this database,the effects of various parameters on the flexural capacity of CRC beams were discussed,including beam width,the effective height of beam section,ratio of strength between longitudinal reinforcement and concrete,concrete compressive strength,and longitudinal reinforcement corrosion ratio.The results indicate that the corrosion of longitudinal reinforcement has the greatest effect on the residual flexural capacity of CRC beams,while other parameters have much less effect.In addition,six available empirical models for calculating the residual flexural strength of CRC beams were also collected and compared with each other based on the established database.It indicates that though five of six existing empirical models underestimate the flexural capacity of CRC beams,there is one model overestimating the flexural capacity.Finally,a newly developed empirical model is proposed to provide accurate and effective predictions in a large range of corrosion ratio for safety assessment of flexural failure of CRC beams confirmed by the comparisons.展开更多
文摘It was found that the steel plate in the composite plate in the WJ-8 fastener used in high speed rail is rusty. The objective of this study is to test the zinc coating of the steel plate. A literature review was conducted to identify the zinc coating techniques, and the companies that can provide different coating service was identified. A salt fog chamber was built that was in compliance with the ANSI B117 code, and the steel plates that were coated by the identified companies were tested using the salt fog chamber. The results indicated that the coating technique that had the best performance in preventing corrosion was the Greenkote plates with passivation. The galvanized option had the roughest coating layer, and it was the most reactive in the salt water solution. This makes it non-ideal for the dynamic rail environment because the increased friction of the plate could damage the supports, especially during extreme temperatures that would cause the rail to expand or contract. Greenkote with Phosphate and ArmorGalv also provided increased corrosion prevention with a smooth, strong finish, but it had more rust on the surface area than the Greenkote with ELU passivation. The ArmorGalv sample had more rust on the surface area than the Greenkote samples. This may not be a weakness in the ArmorGalv process;rather, it likely was the result of this particular sample not having the added protection of a colored coating.
文摘This work is devoted to the study of the inhibition of corrosion of mild steel(MS)in molar hydrochloric acid(1 mol·L-1 HCl)by two named quinoxaline derivatives namely,2-(2,4-dichlorophenyl)-1,4-dihydroquinoxaline(HQ)and 2-(2,4-dichlorophenyl)-6-methyl-1,4-dihydroquinoxaline(CQ).The inhibitory efficacy of HQ and CQ compounds is first evaluated using the gravimetric method and using electrochemical techniques(stationary and transient techniques).The results showed that our compounds are efficient corrosion inhibitors and the inhibition rates(ηEIS%)reached up to 91%and 94.2%at 10-3 mol·L-1 for HQ and CQ,respectively.The mentioned molecules are classified as mixed-type inhibitors.The adsorption of these inhibitors on the surface of steel in hydrochloric HCl 1 mol·L-1 medium obeys the Langmuir adsorption isotherm.The results of the scanning electron microscope(SEM)showed the formation of a protective film on the surface of the steel in the presence of the inhibitors studied.Elementary analysis is obtained by energy dispersive X-ray spectroscopy(EDS).The inhibition property was further elucidated by theoretical approaches such as:Density Functional Theory(DFT),quantum chemical descriptors(QCD),local reactive indices,solvent effect,theoretical complexation,Molecular Dynamic(MD)simulation,effect of temperature on adsorption energy(Eads),Radial Distribution Function(RDF),and Mean Square Displacement(MSD).The results of these approaches support the experimental results.
基金The authors gratefully acknowledge the Project of Young Science and Technology Talents of Jiangsu Province(No.027)the Open Funds by State Key Laboratory of Silicate Materials for Architectures(Wuhan University of Technology)(No.SYSJJ2020-19)+5 种基金the Fundamental Research Funds for the Central Universities(No.B210202023)the Water Conservancy Science and Technology Project of Jiangsu Province(No.2020017)the Open Funds by Key Laboratory of Coastal Disaster and Defense(Hohai University),Ministry of Education(No.202006)the Systematic Project of Guangxi Key Laboratory of Disaster Prevention and Structural Safety(No.2019ZDK006)the Postdoctoral Research Funds of Jiangsu Province(No.2021K133B)the Ningbo Science and Technology Innovation Project(No.2020Z040).
文摘To study the behavior of coral aggregate concrete(CAC)column under axial and eccentric compression,the compression behavior of CAC column with different types of steel and initial eccentricity(ei)were tested,and the deformation behavior and ultimate bearing capacity(Nu)were studied.The results showed that as the ei increases,the Nu of CAC column decreases nonlinearly.Besides,the steel corrosion in CAC column is severe,which reduces the steel section and steel strength,and decreases the Nu of CAC column.The durability of CAC structures can be improved by using new organic coated steel.Considering the influence of steel corrosion and interfacial bond deterioration,the calculation models of Nu under axial and eccentric compression were presented.
基金the funding support from the National Natural Science Foundation of China(No.51571027)
文摘The corrosion behavior of corrosion resistant steel(CRS) in a simulated wet–dry acid humid environment was investigated and compared with carbon steel(CS) using corrosion loss, polarization curves, X-ray diffraction(XRD), scanning electron microscopy(SEM), electron probe micro-analysis(EPMA), N_2 adsorption, and X-ray photoelectron spectroscopy(XPS). The results show that the corrosion kinetics of both steels were closely related to the composition and compactness of the rust, and the electrochemical properties of rusted steel. Small amounts of Cu, Cr, and Ni in CRS increased the amount of amorphous phases and decreased the content of γ-Fe OOH in the rust, resulting in higher compactness and electrochemical stability of the CRS rust. The elements Cu, Cr, and Ni were uniformly distributed in the CRS rust and formed CuFeO_2, Cu_2O, CrOOH, NiFe_2O_4, and Ni_2O_3, which enhanced the corrosion resistance of CRS in the wet–dry acid humid environment.
文摘Electrochemical techniques of the corrosion measurements of reinforcing steeI in concrete have been evaluated. These techniques include half-cell potential measurements, impressed voltage method, impressed current method and potentiostatic polarization technique. The results of corrosion behaviour of the steel in both 5%NaCl and 5%MgSO4 show that each electrochemical technique provides some information about the condition of the steel bar or the corrosivity of the environment being evaluated, yet none provides a complete data regarding the corrosion resistance of reinforcing steel in aggressive
文摘Corrosion and electrochemical behaviour of reinforcing steel embedded in cement pastes with and without concrete admixtures used in Egypt to modify concrete properties have been studied. The influence of the admixtures on the corrosion resistance of the steel against chloride attack has been studied using impressed current and impressed voltage techniques. The results indicate that the type and concentration of the admixture used have an important effed on the extent of chloride induced corrosion of the steel. The mechanism of corrosion of steel due to chloride attack is discussed.
基金Funded by the National Natural Science Foundation of China(No.51774006)。
文摘High-temperature tensile tests were conducted for high corrosion resistant weathering steel S450EW.The morphologies of fracture microstructures,dislocations and precipitates were investigated by field emission scanning electron microscopy and transmission electron microscopy.The high-temperature plastic deformation behavior and brittle mechanism of S450EW steel were also studied.The experimental results show that the ductility troughs appear at 700-850℃ and 650-900℃ when the strain rates are 3×10^(-3)and 1.5×10^(-2)s^(-1),respectively.With the increase of strain rates,the ductility trough moves to the lower temperature side.The hot ductility is best when the cooling rate is 5℃/s before deformation at 750℃and the area reduction rate reaches 60.56%.Fine second phase particles and inclusions precipitated before and during deformation provide effective core positions for microcracks or microvoids formation during deformation process.It is also easy to cause stress concentration which results in microcracks or microvoids between grains during deformation and ultimately causes damage along the grain boundaries.The precipitated particles inhibit austenite dynamic recrystallization and therefore enhance intergranular fracture along austenite grain boundaries.The deformation induced proeutectoid ferrite films distribute along the austenite grain boundaries hinder the dynamic recrystallization.The deformation concentrated on network ferrite films produces damage of grain boundaries.
基金Funded by Gansu Provincial Department of Transport Scientific Research Project(Nos.2017-16,2017-19)Science and Technology Program of Gansu Provincial Department of Housing and Construction(No.JK2021-11)+2 种基金Science and Technology Project of Gansu Provincial Department of Transportation(No.202102)Natural Science Foundation of Gansu Province(No.20JR10RA170)Gansu Provincial Department of Transportation 2021 the First Batch of the Unveiling of the Hanging System Projects。
文摘To investigate the effectiveness of self-made zinc alloy sacrificial anode material for the protection of reinforcement in concrete under chlorine salt erosion environment,salt solution immersion corrosion and electromigration accelerated corrosion tests were used to evaluate the effectiveness of self-made zinc alloy anode with the help of relevant cathodic protection guidelines and evaluation criteria for the corrosion of reinforcement in concrete.The results showed that the protection was effective because the potential of the zinc alloy anode protection steel bar in the salt solution satis?ed the“-780 mV(SCE)”validity criterion.The self-corrosion potential(E_(corr))of the sacri?cial anode protection steel in concrete was greater than-276 mV,and the protective current density of the zinc alloy anode was 1-3μA·cm^(-2),which met the standards of EN12696-2000,further indicating that the self-made zinc alloy sacri?cial anode had a good protection combining with the polarization resistance and the appearance of the corroded surface of the steel in concrete.The microscopic morphology of the corroded surface and the composition of the corrosion products indicates that the mortar of the self-made zinc alloy anode has a lower pH than the imported anodes,so the long-term protection of the selfmade zinc alloy sacri?cial anode needs to be further improved.
基金The authors acknowledge the research supports from the National Natural Science Foundation of China(Grant Nos.51820105014,51738001,U 1934217)the research funds from Australian Research Council(DEI50101751)+1 种基金ARC Industrial Transformation Research Hub Component Project“Nano-geopolymer composites for underground prefabricated structures”with Wuhan Zhihe Geotechnical Engineering Co.,Ltd.The authors are also grateful for the financial supports of the University of Technology Sydney Research Academic Program at Tech Laboratory(UTS RAPT)and University of Technology Sydney Tech Laboratory Blue Sky Research Scheme.
文摘In this study,a total of 177 flexural experimental tests of corroded reinforced concrete(CRC)beams were collected from the published literature.The database of flexural capacity of CRC beam was established by using unified and standardized experimental data.Through this database,the effects of various parameters on the flexural capacity of CRC beams were discussed,including beam width,the effective height of beam section,ratio of strength between longitudinal reinforcement and concrete,concrete compressive strength,and longitudinal reinforcement corrosion ratio.The results indicate that the corrosion of longitudinal reinforcement has the greatest effect on the residual flexural capacity of CRC beams,while other parameters have much less effect.In addition,six available empirical models for calculating the residual flexural strength of CRC beams were also collected and compared with each other based on the established database.It indicates that though five of six existing empirical models underestimate the flexural capacity of CRC beams,there is one model overestimating the flexural capacity.Finally,a newly developed empirical model is proposed to provide accurate and effective predictions in a large range of corrosion ratio for safety assessment of flexural failure of CRC beams confirmed by the comparisons.