Spontaneous electrochemical noise (EN) can be a rich source of information concerning the processes simultaneously occurring on a corroding interface. But the noise signal is often difficult to be analyzed due to the ...Spontaneous electrochemical noise (EN) can be a rich source of information concerning the processes simultaneously occurring on a corroding interface. But the noise signal is often difficult to be analyzed due to the complicated nature of the specific systems being investigated. In this paper, the potential noise fluctuations during the free corrosion of commercial aluminum alloy LY12 in sodium chloride solution was recorded and analyzed with different techniques. The typical results showed that the fractal dimension (D,n) obtained from spectral power density (SPD) is mainly directly proportional to the intensity of pitting corrosion and to the value of pitting parameter (SE) derived from dimensional analysis, while the fractal dimension (DE) obtained from EIS is mainly related to the uniform corrosion.展开更多
Wavelet transforms (WT) are proposed as an alternative tool to overcome the limitations of Fourier transforms (FFT) in the analysis of electrochemical noise (EN) data. The most relevant feature of this method of analy...Wavelet transforms (WT) are proposed as an alternative tool to overcome the limitations of Fourier transforms (FFT) in the analysis of electrochemical noise (EN) data. The most relevant feature of this method of analysis is its capability of decomposing electrochemical noise records into different sets of wavelet coefficients, which contain information about the time scale characteristic of the associated corrosion event. In this context, the potential noise fluctuations during the free corrosion of pure aluminum in sodium chloride solution was recorded and analyzed with wavelet transform technique. The typical results showed that the EN signal is composed of distinct type of events, which can be classified according to their scales, i.e. their time constants. Meanwhile, the energy distribution plot (EDP) can be used as 'fingerprints' of EN signals and can be very useful for analyzing EN data in the future.展开更多
Spontaneous electrochemical noise (EN) can be a rich source of information concerning the processes simultaneously occurring at a corroding interface. Potential noise fluctuations during the free corrosion of pure alu...Spontaneous electrochemical noise (EN) can be a rich source of information concerning the processes simultaneously occurring at a corroding interface. Potential noise fluctuations during the free corrosion of pure aluminum in different concentration of neutral sodium chloride solution are investigated, and the breakdown and restoration of passive metal's film are studied using potentiodynamic scanning (PDS) measurements and electrochemical impedance spectroscopy (EIS) technique. Two capacitance loops are observed in the Nyquist plots in two kinds of concentration, and the corrosion process is under activation control at first, then become diffusion control within the oxide film and corrosion products of (Al(OH)p-mCl-m) accumulated on the surface of the corroding electrode. It is suggested that the pitting corrosion is much easier to occur for pure aluminum in 7.0wt% than in 2.0wt% NaCl solution, and the high concentration of chloride ion in solution inhibits the repassivation of a metastable pit. The corrosion rate deterministic step does not involve Cl-.展开更多
An in situ characterization technique called electrochemical noise(ECN) was used to investigate the bioleaching of natural pyrite.ECN experiments were conducted in four active systems(sulfuric acid,ferric-ion,9k cu...An in situ characterization technique called electrochemical noise(ECN) was used to investigate the bioleaching of natural pyrite.ECN experiments were conducted in four active systems(sulfuric acid,ferric-ion,9k culture medium,and bioleaching solutions).The ECN data were analyzed in both the time and frequency domains.Spectral noise impedance spectra obtained from power spectral density(PSD)plots for different systems were compared.A reaction mechanism was also proposed on the basis of the experimental data analysis.The bioleaching system exhibits the lowest noise resistance of 0.101 MΩ The bioleaching of natural pyrite is considered to be a bio-battery reaction,which distinguishes it from chemical oxidation reactions in ferric-ion and culture-medium(9k) solutions.The corrosion of pyrite becomes more severe over time after the long-term testing of bioleaching.展开更多
The influence of the concentration of Zn2+ ions on zinc electroplating process was investigated by means of electrochemical noise (EN) and cyclic voltammetry methods in conjunction with the scanning electron microscop...The influence of the concentration of Zn2+ ions on zinc electroplating process was investigated by means of electrochemical noise (EN) and cyclic voltammetry methods in conjunction with the scanning electron microscopy (SEM) technique. It was found that the EN generated during the electroplating of dentritic or large polymeric zinc deposit has large potential oscillation amplitude and positive potential drift while the compact zinc deposit possesses small noise amplitude and little potential drift. With the change of rate determining step from diffusion-control through mixed-control to activation-control, the maximum relative energy obtained from wavelet analysis defined from the region with larger scales to those with smaller scales, and the EDP (relative energy distribution plot) can be us, as 'fingerprints' of EN to characterize the electroplating process and the deposit structure. The results also showed that electrochemical noise technique can give more information about the electrodeposit structure than other normal electrochemical measurements, such as linear potential sweep method and cyclic voltammetry technique.展开更多
The influence of H3BO3 on the zinc electroplating was studied using electrochemical noise technique, cyclic voltammetry and steady-state polarization method. The results showed that, under the experimental conditions,...The influence of H3BO3 on the zinc electroplating was studied using electrochemical noise technique, cyclic voltammetry and steady-state polarization method. The results showed that, under the experimental conditions, the deposition of zinc followed the mechanism of two-dimensional nucleation and subsequent grain growth. The addition of H3BO3 into the electroplating solution prominently changes the nucleation and growth kinetics of zinc deposits, which is directly related to the features of electrocrystallization noise and the corresponding structure of the electrodeposits. The results also shown that the electrochemical noise (EN) technique can give more information about the electrodeposits structure and electroplating mechanism than other normal electrochemical measurements can give, such as steady-state polarization method and cyclic voltammetry technique.展开更多
The influence mechanism of pH and the externally applied stress on sulfide stress corrosion cracking behavior based on the joint analysis of the in situ electrochemical noise and microstructure was studied.The results...The influence mechanism of pH and the externally applied stress on sulfide stress corrosion cracking behavior based on the joint analysis of the in situ electrochemical noise and microstructure was studied.The results showed that{\mathrm{H}}^{+}in solution changes the composition and structure of corrosion product film by affecting the concentration of{\mathrm{S}}^{2-}and{\mathrm{Fe}}^{2+}near the anode surface.When the pH increased from 2.6 to 3.6 and 4.6,the corrosion product film changed from porous Mackinawite to dense and stable FeS.The change in corrosion product type delayed the crack initiation time by 10.5 and 45.5 h,while the uniform corrosion time was prolonged by 6.1 and 46 h,respectively,delaying SSC behavior.After increasing the applied stress,the local plastic deformation on the material surface increases the porosity and crack rate of the corrosion product film and becomes a fast propagation channel for SSC cracks.When the applied stress is 110%of the actual yield strength of the material,the initiation time of stress corrosion cracking is 6 and 18.1 h earlier than that of 90%and 100%,respectively.The local corrosion time was extended by 23.5 and 8.2 h,respectively,accelerating SSC behavior.展开更多
Magnesium alloys have been investigated as biodegradable implant materials since the last century. Non-uniform degradation caused by local corrosion limits their application, and no appropriate technology has been use...Magnesium alloys have been investigated as biodegradable implant materials since the last century. Non-uniform degradation caused by local corrosion limits their application, and no appropriate technology has been used in the research. In this study, electrochemical noise has been used to study the pit corrosion on magnesium alloy AZ31 in four types of simulated body solutions, and the data have been analyzed using wavelet analysis and stochastic theory. Combining these with the conventional polarization curves, mass loss tests and scanning electron microscopy, the electrochemical noise results implied that AZ31 alloy in normal saline has the fastest corrosion rate, a high pit initiation rate, and maximum pit growth probability. In Hanks' balanced salt solution and phosphate-buffered saline, AZ31 alloy has a high pit initiation rate and larger pit growth probability, while in simulated body fluid, AZ31 alloy has the slowest corrosion rate, lowest pit initiation rate and smallest pit growth probability.展开更多
The sulfide stress corrosion(SSC)behaviors of the high strength low alloy steel at the different temperatures were investigated by the microstructural observation and electrochemical noise(EN)analysis.With the corrosi...The sulfide stress corrosion(SSC)behaviors of the high strength low alloy steel at the different temperatures were investigated by the microstructural observation and electrochemical noise(EN)analysis.With the corrosion temperature increasing from 20 to 40℃,SSC ruptured time is prolonged.The increase in corrosion temperature results in the decrease of the saturation solubility of H_(2)S in the solution and thus increases pH value of solution.The increase in corrosion temperature decreases the size of the holes and cracks in the corrosion product film on the surface of the sample,which is due to the formation of the dense FeS corrosion product film.The current kurtosis results indicate that the time for the first occurrence of crack initiation is postponed by the increase in the corrosion temperature.The standard deviation of current noise signals,current kurtosis,power spectral density and energy distribution plot results shows a great consistency,which suggests that EN analysis method can reflect SSC behaviors in real time.展开更多
The critical pitting temperature (CPT) of 2101 lean duplex stainless steel (DSS) in 1 mol/L NaCl was investigated.Potentiostatic electrochemical noise (EN) technique coupled with scanning electron microscopy (...The critical pitting temperature (CPT) of 2101 lean duplex stainless steel (DSS) in 1 mol/L NaCl was investigated.Potentiostatic electrochemical noise (EN) technique coupled with scanning electron microscopy (SEM) was used to study the corrosion process of 2101 DSS at different temperatures (15,25,28,and 35 C) from below CPT to above CPT.The EN data were analyzed by wavelet technique based on orthogonal db4 wavelet.The results showed that,the patterns of current noises were different at different temperatures.The characteristics of energy distribution plot (EDP) obtained from wavelet analysis technique can be used as "fingerprints" of EN signal and can be used to interpret the corrosion process.With increasing solution temperature,the maximum relative energy defined in EDP changed from the region of crystal series coefficients with smaller scales through middle scales to larger scales,which indicated the process of initiation,propagation and growth into stable pitting of metastable pitting.The results were well confirmed by the corresponding morphologies.展开更多
This work aimed to in-situ monitor the atmospheric corrosion of steels exposed to Zhoushan offshore environment by using electrochemical noise(EN) technique. A portable EN monitoring system was established and two e...This work aimed to in-situ monitor the atmospheric corrosion of steels exposed to Zhoushan offshore environment by using electrochemical noise(EN) technique. A portable EN monitoring system was established and two electrochemical probes(named as Q235 B and T91) were designed. Experimental results indicated that the noise resistance of T91 steel was higher than that of Q235 B steel, revealing that the corrosion resistance of T91 was higher than that of Q235 B. A 60-day monitoring result indicated that the noise resistance was well correlated with the weight loss data. Wavelet analyses results of EN data indicated that Q235 B underwent uniform corrosion and T91 suffered from localized corrosion, which was further confirmed by the surface observation. It is concluded that EN can be used as a new method to identify the corrosion form and corrosion resistance in atmospheric conditions.展开更多
The corrosion behavior of 304L stainless steel(SS)in 3.5wt%NaCl solution after different cavitation erosion(CE)times was mainly evaluated using electrochemical noise and potentiostatic polarization techniques.It was f...The corrosion behavior of 304L stainless steel(SS)in 3.5wt%NaCl solution after different cavitation erosion(CE)times was mainly evaluated using electrochemical noise and potentiostatic polarization techniques.It was found that the antagonism effect resulting in the passivation and depassivation of 304L SS had significant distinctions at different CE periods.The passive behavior was predominant during the incubation period of CE where the metastable pitting initiated at the surface of 304L SS.Over the rising period of CE,the 304L SS experienced a transition from passivation to depassivation,leading to the massive growth of metastable pitting and stable pitting.The depassivation of304L SS was found to be dominant at the stable period of CE where serious localized corrosion occurred.展开更多
The corrosion process of phenolic epoxy coated tinplate in energy drink was investigated by in-situ electrochemical impedance spectroscopy(EIS) and electrochemical noise(EN) techniques. The experimental results in...The corrosion process of phenolic epoxy coated tinplate in energy drink was investigated by in-situ electrochemical impedance spectroscopy(EIS) and electrochemical noise(EN) techniques. The experimental results indicate that the degradation process of novolac epoxy coated tinplate in energy drink can be divided into three main stages: organic coating wetted by the beverage; corrosion initiation beneath the organic coating; and corrosion extension process. It was proposed that the tin coating and carbon steel were mainly corroded by organic acids in energy drink through the pores of the organic coating. After the tin coating was corroded, the carbon steel started to corrode due to its higher electrochemical activity and became to be the dominated corrosion reaction.展开更多
A wide variety of inhibitive pigments is now being offered as possible alternatives to chromate and lead compounds for painted metals protection. Unfortunately, the most wide spread of these substitute pigments, zinc ...A wide variety of inhibitive pigments is now being offered as possible alternatives to chromate and lead compounds for painted metals protection. Unfortunately, the most wide spread of these substitute pigments, zinc phosphate, has, at present, raised some environmental concern because phosphate causes the eutrophication of water courses and zinc itself is toxic. The aim of this re-search was to study the anticorrosive performance of a mixture consisting of zinc phosphate, modified zeolite and clay (bentonite) in order to diminish phosphate content in paints. The zeolite and the clay were exchanged with La(III) ions, as inorganic green inhibitor. In the first step, the anticorrosion protection by La(III) ions in solution was assessed by electrochemical tests. In the second step, an epoxy-polyamide paint formulated with the pigment mixture applied on galvanized panels was studied by salt spray test and electro-chemical noise measurements (ENM). The results showed that it was possible to replace part of the zinc phosphate content in the paint with the exchanged zeolite and the clay.展开更多
基金Acknowledgements - The authors wish to acknowledge the financial support of the National Key Basic Research Foundation of China
文摘Spontaneous electrochemical noise (EN) can be a rich source of information concerning the processes simultaneously occurring on a corroding interface. But the noise signal is often difficult to be analyzed due to the complicated nature of the specific systems being investigated. In this paper, the potential noise fluctuations during the free corrosion of commercial aluminum alloy LY12 in sodium chloride solution was recorded and analyzed with different techniques. The typical results showed that the fractal dimension (D,n) obtained from spectral power density (SPD) is mainly directly proportional to the intensity of pitting corrosion and to the value of pitting parameter (SE) derived from dimensional analysis, while the fractal dimension (DE) obtained from EIS is mainly related to the uniform corrosion.
基金the financial support of the National Key Basic Research Foundation of China (Project G19990650), the National Natural Science Foundation of China (Project 50071054) and the financial support of State Key
文摘Wavelet transforms (WT) are proposed as an alternative tool to overcome the limitations of Fourier transforms (FFT) in the analysis of electrochemical noise (EN) data. The most relevant feature of this method of analysis is its capability of decomposing electrochemical noise records into different sets of wavelet coefficients, which contain information about the time scale characteristic of the associated corrosion event. In this context, the potential noise fluctuations during the free corrosion of pure aluminum in sodium chloride solution was recorded and analyzed with wavelet transform technique. The typical results showed that the EN signal is composed of distinct type of events, which can be classified according to their scales, i.e. their time constants. Meanwhile, the energy distribution plot (EDP) can be used as 'fingerprints' of EN signals and can be very useful for analyzing EN data in the future.
基金The authors wish to acknowledge the financial support of the national key basic research foundation of China (Grant No. G19990650), the National Natural Science Foundation of China (Grant No. 50071054) and State key Laboratory for Corrosion and Protecti
文摘Spontaneous electrochemical noise (EN) can be a rich source of information concerning the processes simultaneously occurring at a corroding interface. Potential noise fluctuations during the free corrosion of pure aluminum in different concentration of neutral sodium chloride solution are investigated, and the breakdown and restoration of passive metal's film are studied using potentiodynamic scanning (PDS) measurements and electrochemical impedance spectroscopy (EIS) technique. Two capacitance loops are observed in the Nyquist plots in two kinds of concentration, and the corrosion process is under activation control at first, then become diffusion control within the oxide film and corrosion products of (Al(OH)p-mCl-m) accumulated on the surface of the corroding electrode. It is suggested that the pitting corrosion is much easier to occur for pure aluminum in 7.0wt% than in 2.0wt% NaCl solution, and the high concentration of chloride ion in solution inhibits the repassivation of a metastable pit. The corrosion rate deterministic step does not involve Cl-.
基金supported by the National Natural Science Foundation of China (Nos. 51304047 and 51374066)the Ph.D. Programs Foundation of the Ministry of Education of China (No.20130042120040)
文摘An in situ characterization technique called electrochemical noise(ECN) was used to investigate the bioleaching of natural pyrite.ECN experiments were conducted in four active systems(sulfuric acid,ferric-ion,9k culture medium,and bioleaching solutions).The ECN data were analyzed in both the time and frequency domains.Spectral noise impedance spectra obtained from power spectral density(PSD)plots for different systems were compared.A reaction mechanism was also proposed on the basis of the experimental data analysis.The bioleaching system exhibits the lowest noise resistance of 0.101 MΩ The bioleaching of natural pyrite is considered to be a bio-battery reaction,which distinguishes it from chemical oxidation reactions in ferric-ion and culture-medium(9k) solutions.The corrosion of pyrite becomes more severe over time after the long-term testing of bioleaching.
基金This work was supported by the National Natural Science Foundation of China(No.20203015 and No.50499335).
文摘The influence of the concentration of Zn2+ ions on zinc electroplating process was investigated by means of electrochemical noise (EN) and cyclic voltammetry methods in conjunction with the scanning electron microscopy (SEM) technique. It was found that the EN generated during the electroplating of dentritic or large polymeric zinc deposit has large potential oscillation amplitude and positive potential drift while the compact zinc deposit possesses small noise amplitude and little potential drift. With the change of rate determining step from diffusion-control through mixed-control to activation-control, the maximum relative energy obtained from wavelet analysis defined from the region with larger scales to those with smaller scales, and the EDP (relative energy distribution plot) can be us, as 'fingerprints' of EN to characterize the electroplating process and the deposit structure. The results also showed that electrochemical noise technique can give more information about the electrodeposit structure than other normal electrochemical measurements, such as linear potential sweep method and cyclic voltammetry technique.
基金supported by the National Natural Science Foundation of China(Grant No.20203015).
文摘The influence of H3BO3 on the zinc electroplating was studied using electrochemical noise technique, cyclic voltammetry and steady-state polarization method. The results showed that, under the experimental conditions, the deposition of zinc followed the mechanism of two-dimensional nucleation and subsequent grain growth. The addition of H3BO3 into the electroplating solution prominently changes the nucleation and growth kinetics of zinc deposits, which is directly related to the features of electrocrystallization noise and the corresponding structure of the electrodeposits. The results also shown that the electrochemical noise (EN) technique can give more information about the electrodeposits structure and electroplating mechanism than other normal electrochemical measurements can give, such as steady-state polarization method and cyclic voltammetry technique.
基金supported by the National Key R&D Program of China(2022YFB3705300)the National Natural Science Foundation of China(Nos.52034004,52271111 and 52171123).
文摘The influence mechanism of pH and the externally applied stress on sulfide stress corrosion cracking behavior based on the joint analysis of the in situ electrochemical noise and microstructure was studied.The results showed that{\mathrm{H}}^{+}in solution changes the composition and structure of corrosion product film by affecting the concentration of{\mathrm{S}}^{2-}and{\mathrm{Fe}}^{2+}near the anode surface.When the pH increased from 2.6 to 3.6 and 4.6,the corrosion product film changed from porous Mackinawite to dense and stable FeS.The change in corrosion product type delayed the crack initiation time by 10.5 and 45.5 h,while the uniform corrosion time was prolonged by 6.1 and 46 h,respectively,delaying SSC behavior.After increasing the applied stress,the local plastic deformation on the material surface increases the porosity and crack rate of the corrosion product film and becomes a fast propagation channel for SSC cracks.When the applied stress is 110%of the actual yield strength of the material,the initiation time of stress corrosion cracking is 6 and 18.1 h earlier than that of 90%and 100%,respectively.The local corrosion time was extended by 23.5 and 8.2 h,respectively,accelerating SSC behavior.
基金financially supported by the National Natural Science Foundation of China(Nos.51701221 and 51501201)
文摘Magnesium alloys have been investigated as biodegradable implant materials since the last century. Non-uniform degradation caused by local corrosion limits their application, and no appropriate technology has been used in the research. In this study, electrochemical noise has been used to study the pit corrosion on magnesium alloy AZ31 in four types of simulated body solutions, and the data have been analyzed using wavelet analysis and stochastic theory. Combining these with the conventional polarization curves, mass loss tests and scanning electron microscopy, the electrochemical noise results implied that AZ31 alloy in normal saline has the fastest corrosion rate, a high pit initiation rate, and maximum pit growth probability. In Hanks' balanced salt solution and phosphate-buffered saline, AZ31 alloy has a high pit initiation rate and larger pit growth probability, while in simulated body fluid, AZ31 alloy has the slowest corrosion rate, lowest pit initiation rate and smallest pit growth probability.
基金the National Natural Science Foundation of China(Grant Nos.51975404,52034004 and 52171123)for grant and financial support.
文摘The sulfide stress corrosion(SSC)behaviors of the high strength low alloy steel at the different temperatures were investigated by the microstructural observation and electrochemical noise(EN)analysis.With the corrosion temperature increasing from 20 to 40℃,SSC ruptured time is prolonged.The increase in corrosion temperature results in the decrease of the saturation solubility of H_(2)S in the solution and thus increases pH value of solution.The increase in corrosion temperature decreases the size of the holes and cracks in the corrosion product film on the surface of the sample,which is due to the formation of the dense FeS corrosion product film.The current kurtosis results indicate that the time for the first occurrence of crack initiation is postponed by the increase in the corrosion temperature.The standard deviation of current noise signals,current kurtosis,power spectral density and energy distribution plot results shows a great consistency,which suggests that EN analysis method can reflect SSC behaviors in real time.
基金supported by the National Natural Science Foundation of China (Grant.Nos. 51131008,51134010 and 51071049)the Graduate Innovation Funding from Fudan University
文摘The critical pitting temperature (CPT) of 2101 lean duplex stainless steel (DSS) in 1 mol/L NaCl was investigated.Potentiostatic electrochemical noise (EN) technique coupled with scanning electron microscopy (SEM) was used to study the corrosion process of 2101 DSS at different temperatures (15,25,28,and 35 C) from below CPT to above CPT.The EN data were analyzed by wavelet technique based on orthogonal db4 wavelet.The results showed that,the patterns of current noises were different at different temperatures.The characteristics of energy distribution plot (EDP) obtained from wavelet analysis technique can be used as "fingerprints" of EN signal and can be used to interpret the corrosion process.With increasing solution temperature,the maximum relative energy defined in EDP changed from the region of crystal series coefficients with smaller scales through middle scales to larger scales,which indicated the process of initiation,propagation and growth into stable pitting of metastable pitting.The results were well confirmed by the corresponding morphologies.
基金Funded by the National Natural Science Foundation of China(Nos.51701140 and 51371124)the Major State Basic Research Development Program(973 Program)(No.2014CB046805)
文摘This work aimed to in-situ monitor the atmospheric corrosion of steels exposed to Zhoushan offshore environment by using electrochemical noise(EN) technique. A portable EN monitoring system was established and two electrochemical probes(named as Q235 B and T91) were designed. Experimental results indicated that the noise resistance of T91 steel was higher than that of Q235 B steel, revealing that the corrosion resistance of T91 was higher than that of Q235 B. A 60-day monitoring result indicated that the noise resistance was well correlated with the weight loss data. Wavelet analyses results of EN data indicated that Q235 B underwent uniform corrosion and T91 suffered from localized corrosion, which was further confirmed by the surface observation. It is concluded that EN can be used as a new method to identify the corrosion form and corrosion resistance in atmospheric conditions.
基金financially supported of the National Natural Science Foundation of China (Nos.52101105 and 51975263)。
文摘The corrosion behavior of 304L stainless steel(SS)in 3.5wt%NaCl solution after different cavitation erosion(CE)times was mainly evaluated using electrochemical noise and potentiostatic polarization techniques.It was found that the antagonism effect resulting in the passivation and depassivation of 304L SS had significant distinctions at different CE periods.The passive behavior was predominant during the incubation period of CE where the metastable pitting initiated at the surface of 304L SS.Over the rising period of CE,the 304L SS experienced a transition from passivation to depassivation,leading to the massive growth of metastable pitting and stable pitting.The depassivation of304L SS was found to be dominant at the stable period of CE where serious localized corrosion occurred.
基金Funded by the National Key Basic Research Program of China(2011CB610505)the Specialized Research Fund for the Doctoral Program of Higher Education(20120032110029)
文摘The corrosion process of phenolic epoxy coated tinplate in energy drink was investigated by in-situ electrochemical impedance spectroscopy(EIS) and electrochemical noise(EN) techniques. The experimental results indicate that the degradation process of novolac epoxy coated tinplate in energy drink can be divided into three main stages: organic coating wetted by the beverage; corrosion initiation beneath the organic coating; and corrosion extension process. It was proposed that the tin coating and carbon steel were mainly corroded by organic acids in energy drink through the pores of the organic coating. After the tin coating was corroded, the carbon steel started to corrode due to its higher electrochemical activity and became to be the dominated corrosion reaction.
基金Project supported by CONICET(Consejo Nacional de Investigaciones Científicas y Técnicas)UNLP(Universidad Nacional de La Plata)CICPBA(Comisión de Investigaciones Científicas de la Provincia de Buenos Aires)
文摘A wide variety of inhibitive pigments is now being offered as possible alternatives to chromate and lead compounds for painted metals protection. Unfortunately, the most wide spread of these substitute pigments, zinc phosphate, has, at present, raised some environmental concern because phosphate causes the eutrophication of water courses and zinc itself is toxic. The aim of this re-search was to study the anticorrosive performance of a mixture consisting of zinc phosphate, modified zeolite and clay (bentonite) in order to diminish phosphate content in paints. The zeolite and the clay were exchanged with La(III) ions, as inorganic green inhibitor. In the first step, the anticorrosion protection by La(III) ions in solution was assessed by electrochemical tests. In the second step, an epoxy-polyamide paint formulated with the pigment mixture applied on galvanized panels was studied by salt spray test and electro-chemical noise measurements (ENM). The results showed that it was possible to replace part of the zinc phosphate content in the paint with the exchanged zeolite and the clay.