Stainless steel(SS)is one of the most widely used engineering materials in marine engineering.However,its corrosion in the marine atmospheric environment due to the high concentration of Cl-is a problem.The SS corrosi...Stainless steel(SS)is one of the most widely used engineering materials in marine engineering.However,its corrosion in the marine atmospheric environment due to the high concentration of Cl-is a problem.The SS corrosion is a threat to the development and security of marine industry;therefore,evaluating the corrosion resistance of SSs is necessary.In this work,atmospheric corrosion detection probes based on a symmetrical electrode system were used to study the corrosion behaviors of 304 SS and 2205 duplex stainless steel(DSS)in a simulated marine atmosphere.A theoretical model for electrochemical noise(EN)data analysis based on the Thevenin electrochemical equivalent circuit(EEC)model was established.The relationship between the EN characteristic parameters and the corrosion rate was obtained.The Thevenin EEC model analysis showed that the relationship between the noise resistance(Rn),the noise impedance[Rsn(f)],and the impedance modulus(|Z(f)|)was Rn≈Rsn=■.Thus,Rn and Rsn can be used as indicators for quantitative corrosion evaluation.The results of EN detection for the 304 SS and 2205 DSS showed that in a simulated marine atmospheric environment,the passive fi lms on the two SSs were relatively intact at the initial exposure stage,and their dissolution rates were slow.The corrosion resistance of the 2205 DSS was higher than that of the 304 SS.With the deposition of Cl-on the SS surface,pitting was initiated and the dissolution rate increased.The pitting initiation process on the SS surface was random,and part of the active pores could be repassivated.展开更多
The purpose of this work was to enhance the corrosion resistance of the passive fi lm on 304 stainless steel(SS)by chemical modifi cation in alkaline phosphate–molybdate solutions.The 304 SS was passivated in both ph...The purpose of this work was to enhance the corrosion resistance of the passive fi lm on 304 stainless steel(SS)by chemical modifi cation in alkaline phosphate–molybdate solutions.The 304 SS was passivated in both phosphate and phosphate–molybdate mixed solutions to investigate the eff ect of molybdate on its corrosion resistance.The experimental results indicated that the passive fi lm showed better corrosion resistance in Cl?-containing solutions after modifi cation in phosphate–molybdate solutions than in phosphate-only solutions.Energy-dispersive spectroscopy analyses revealed that the passive fi lm formed in phosphate–molybdate solutions contained Mo and P after modifi cation,which is the reason for the enhanced corrosion resistance.展开更多
Corrosion degradation is detrimental to metal structures as it shortens their lifetime and leads to huge economic losses and unexpected disasters.Therefore,the detection and monitoring of corrosion degradation is of g...Corrosion degradation is detrimental to metal structures as it shortens their lifetime and leads to huge economic losses and unexpected disasters.Therefore,the detection and monitoring of corrosion degradation is of great importance.Herein,we briefly review the state-of-the-art electrochemical methods,instrumentation(based on virtual instrumentation),and advanced sensor/probes that are used in the field for the assessment of corrosion damage.Typical corrosion monitoring results,some of which have been obtained at Tianjin University in the past 30 years,for metallic materials and organic coating/metal systems in atmospheric,marine,and soil conditions in the field are presented.Detection methods,data analysis,and theoretical and mathematical models regarding each corrosion system are discussed,and the challenges,problems and possible solutions for each case are suggested.Lastly,future developments,such as wireless,intelligent,and automatic electrochemical measurement,that will augment the present electrochemical methods of evaluating corrosion degradation are summarized.展开更多
Material degradation is accompanied by the changes in surface structure,morphology,and composition.These changes can be recorded by a variety of image acquisition devices that export digital images in grayscale or tru...Material degradation is accompanied by the changes in surface structure,morphology,and composition.These changes can be recorded by a variety of image acquisition devices that export digital images in grayscale or true color to a detector.Information regarding corrosion type and extent can be extracted with image processing methods.This paper provides a comprehensive review of material degradation assessed by digital image processing.Digital image processing systems used to assess material degradation are briefly reviewed,and the algorithms developed to process metallic materials degradation images are described.Physical and electrochemical methods that can be used to support digital image processing results are summarized,and future work that will augment the present methods of evaluating material degradation are discussed.展开更多
The effects of chloride and thiosulfate ions on localized corrosion of alloy 800 are investigated through dynamical observation of the change in phase image of the diffusion layer during passive film breakdown using d...The effects of chloride and thiosulfate ions on localized corrosion of alloy 800 are investigated through dynamical observation of the change in phase image of the diffusion layer during passive film breakdown using digital holography. The results indicate that solution chemistry has a significant effect on film breakdown and diffusion layer. The phase distribution changes at different applied potentials show that in the process of film breakdown, dissolution of metal ions from pitting is not remarkable in chloride-only solution, whereas dissolution of metal ions is significantly high in thiosulfate and chloride solution. Thiosulfate has a combined effect with chloride ions in passive film degradation.展开更多
基金the National Natural Science Foundation of China(No.51701140)。
文摘Stainless steel(SS)is one of the most widely used engineering materials in marine engineering.However,its corrosion in the marine atmospheric environment due to the high concentration of Cl-is a problem.The SS corrosion is a threat to the development and security of marine industry;therefore,evaluating the corrosion resistance of SSs is necessary.In this work,atmospheric corrosion detection probes based on a symmetrical electrode system were used to study the corrosion behaviors of 304 SS and 2205 duplex stainless steel(DSS)in a simulated marine atmosphere.A theoretical model for electrochemical noise(EN)data analysis based on the Thevenin electrochemical equivalent circuit(EEC)model was established.The relationship between the EN characteristic parameters and the corrosion rate was obtained.The Thevenin EEC model analysis showed that the relationship between the noise resistance(Rn),the noise impedance[Rsn(f)],and the impedance modulus(|Z(f)|)was Rn≈Rsn=■.Thus,Rn and Rsn can be used as indicators for quantitative corrosion evaluation.The results of EN detection for the 304 SS and 2205 DSS showed that in a simulated marine atmospheric environment,the passive fi lms on the two SSs were relatively intact at the initial exposure stage,and their dissolution rates were slow.The corrosion resistance of the 2205 DSS was higher than that of the 304 SS.With the deposition of Cl-on the SS surface,pitting was initiated and the dissolution rate increased.The pitting initiation process on the SS surface was random,and part of the active pores could be repassivated.
基金supported by the National Natural Science Foundation of China(No.51701140).
文摘The purpose of this work was to enhance the corrosion resistance of the passive fi lm on 304 stainless steel(SS)by chemical modifi cation in alkaline phosphate–molybdate solutions.The 304 SS was passivated in both phosphate and phosphate–molybdate mixed solutions to investigate the eff ect of molybdate on its corrosion resistance.The experimental results indicated that the passive fi lm showed better corrosion resistance in Cl?-containing solutions after modifi cation in phosphate–molybdate solutions than in phosphate-only solutions.Energy-dispersive spectroscopy analyses revealed that the passive fi lm formed in phosphate–molybdate solutions contained Mo and P after modifi cation,which is the reason for the enhanced corrosion resistance.
基金the National Natural Science Foundation of China(Nos.52031007,52171077)partial support of his contribution to the work by the University of California at Berkeley。
文摘Corrosion degradation is detrimental to metal structures as it shortens their lifetime and leads to huge economic losses and unexpected disasters.Therefore,the detection and monitoring of corrosion degradation is of great importance.Herein,we briefly review the state-of-the-art electrochemical methods,instrumentation(based on virtual instrumentation),and advanced sensor/probes that are used in the field for the assessment of corrosion damage.Typical corrosion monitoring results,some of which have been obtained at Tianjin University in the past 30 years,for metallic materials and organic coating/metal systems in atmospheric,marine,and soil conditions in the field are presented.Detection methods,data analysis,and theoretical and mathematical models regarding each corrosion system are discussed,and the challenges,problems and possible solutions for each case are suggested.Lastly,future developments,such as wireless,intelligent,and automatic electrochemical measurement,that will augment the present electrochemical methods of evaluating corrosion degradation are summarized.
基金financially supported by the National Natural Science Foundation of China(No.51701140)。
文摘Material degradation is accompanied by the changes in surface structure,morphology,and composition.These changes can be recorded by a variety of image acquisition devices that export digital images in grayscale or true color to a detector.Information regarding corrosion type and extent can be extracted with image processing methods.This paper provides a comprehensive review of material degradation assessed by digital image processing.Digital image processing systems used to assess material degradation are briefly reviewed,and the algorithms developed to process metallic materials degradation images are described.Physical and electrochemical methods that can be used to support digital image processing results are summarized,and future work that will augment the present methods of evaluating material degradation are discussed.
基金supported by Natural Sciences and Engineering Research Council of Canada Discovery GrantNational Natural Science Foundation of China (No. 51371124)
文摘The effects of chloride and thiosulfate ions on localized corrosion of alloy 800 are investigated through dynamical observation of the change in phase image of the diffusion layer during passive film breakdown using digital holography. The results indicate that solution chemistry has a significant effect on film breakdown and diffusion layer. The phase distribution changes at different applied potentials show that in the process of film breakdown, dissolution of metal ions from pitting is not remarkable in chloride-only solution, whereas dissolution of metal ions is significantly high in thiosulfate and chloride solution. Thiosulfate has a combined effect with chloride ions in passive film degradation.
