The corrosion process of copper in thermal flow system was investigated through the experimental bench.According to surface variation of samples during corrosion process,the surface model of specimen was build up base...The corrosion process of copper in thermal flow system was investigated through the experimental bench.According to surface variation of samples during corrosion process,the surface model of specimen was build up based on Gaussian filter.The results show that the corrosion characterization of copper in thermal flow system is pitting corrosion.The morphology characterizations of metal corrosion process can be described using the proposed surface model.The generation and development of copper pitting process can be observed clearly.展开更多
The morphology analysis and electrochemical method were used to study the corrosion behavior of LaFe11.6Si1.4 alloy of copper ion implantation. X-ray photoelectron spectroscopy (XPS) and atomic emission spectroscopy...The morphology analysis and electrochemical method were used to study the corrosion behavior of LaFe11.6Si1.4 alloy of copper ion implantation. X-ray photoelectron spectroscopy (XPS) and atomic emission spectroscopy (AES) research results showed that a 15 nm-thick oxide film was formed on the surface of sample, and the copper content reached the highest value at 60 nm with a normal distribution. Immersion experiments indicated that the corrosion happened in the copper-poor zone firstly and a galvanic connection was formed among different zones on the surface due to the inhomogeneous distribution of copper. Electrochemical experiment results showed that the corrosion was serious when the ion acceleration voltage increased, and the high acceleration could reduce the thermodynamic performance of corrosion of LaFe11.6Si1.4 alloy.展开更多
The corrosion behaviours of Mg-5Y-7Gd-1Nd-0.5Zr magnesium alloys prepared by as-casting and extrusion were investigated in 5% NaCl aqueous solution by immersion and electrochemical tests. The microstructure indicates ...The corrosion behaviours of Mg-5Y-7Gd-1Nd-0.5Zr magnesium alloys prepared by as-casting and extrusion were investigated in 5% NaCl aqueous solution by immersion and electrochemical tests. The microstructure indicates the mean grain size of 15 μm for the extruded and 100 μm for the as-cast Mg-5Y-7Gd-1Nd-0.5Zr magnesium alloys. The corrosion morphology of as-cast sample shows pitting corrosion and little filiform corrosion, but that of the extruded sample shows pitting corrosion at the initial stage. The corrosion rate of extruded sample is higher than that of as-cast Mg-5Y-7Gd-1Nd-0.5Zr alloy according to the immersion test. The second phases containing RE acting as cathodes improve the corrosion properties. The corrosion potentials of as-cast and extruded Mg-5Y-7Gd-1Nd-0.5Zr alloys are -1.658 V and -1.591 V, respectively. The origins of the distinctive corrosion behavior of as-cast and extruded Mg-5Y-7Gd-1Nd-0.5Zr Mg alloys were discussed.展开更多
The corrosion behavior of Mg-8Li-3Zn-Al alloy was investigated in neutral 3.5%NaCl aqueous solution by morphology observation and electrochemical tests.The weight loss method was to measure the corrosion rate.The elec...The corrosion behavior of Mg-8Li-3Zn-Al alloy was investigated in neutral 3.5%NaCl aqueous solution by morphology observation and electrochemical tests.The weight loss method was to measure the corrosion rate.The electrochemical results indicated that the corrosion resistance of Mg-8Li-3Zn-Al alloy in 3.5%NaCl solution is poorer than that in distilled water.The Cl-anion leads to the initiation and development of the corrosion pits.And the corrosion products are mainly Mg(OH)_(2).展开更多
Experiments were performed to study the pitting corrosion morphology of 304 stainless steel exposed to FeCl 3 environments and SEM micrographs of the pitting corrosion morphology were obtained. The image processing te...Experiments were performed to study the pitting corrosion morphology of 304 stainless steel exposed to FeCl 3 environments and SEM micrographs of the pitting corrosion morphology were obtained. The image processing technique combining with the fractal method was employed to analyze these pitting corrosion images and the self-similarity of pits morphology was observed. It indicates that fractal characteristics exist in pitting corrosion of 304 stainless steel. The self-similarity and complexity of the pitting morphology phenomenon were described in terms of fractal dimension which can also be an important parameter related to characterize pitting morphology qualitatively and quantitatively.展开更多
This paper studied the influence of aging treatment on the corrosion behavior and mechanism of Mg-Y alloys with different Y content through corrosion mass loss test, electrochemical test and corrosion morphologies obs...This paper studied the influence of aging treatment on the corrosion behavior and mechanism of Mg-Y alloys with different Y content through corrosion mass loss test, electrochemical test and corrosion morphologies observation. Results show that the peak-aging times of Mg-(0.25, 2.5, 5, 8 and 15) Y alloys at 250 ℃ were 4, 6, 10, 12 and 16 h. The aging treatment reduced the corrosion resistance of Mg-Y alloys, and the corrosion resistance of Mg-Y alloys became worse with increasing of the aging time. The change magnitude of the open circuit potentials for Mg-(0.25, 2.5)Y alloys was greater than that of Mg-(5, 8 and 15)-Y alloys. The polarization curves of Mg (0.25, 2.5, 5, 8 and 15) Y alloys had the similar shape after aging treatment, and the slopes of the anodic branch were greater than those of the cathodic branches. After aging treatment, the corrosion modes of Mg-0.25Y and Mg-(2.5, 5, 8 and 15) Y alloys were uniform corrosion and pitting corrosion with small local deep corrosion.展开更多
To explore the corrosion properties of magnesium alloys, the chemical behavior of a high strength Mg_(97)Zn_(1)Y_(2)-1 wt.%Si C alloy in different corrosion environments was studied. Three solutions of 0.2 mol·L^...To explore the corrosion properties of magnesium alloys, the chemical behavior of a high strength Mg_(97)Zn_(1)Y_(2)-1 wt.%Si C alloy in different corrosion environments was studied. Three solutions of 0.2 mol·L^(-1) NaCl, Na_(2)SO_(4) and NaNO_(3) were selected as corrosion solutions. The microstructures, corrosion rate, corrosion potential, and mechanism were investigated qualitatively and quantitatively by optical microscopy(OM), scanning electron microscopy(SEM), immersion testing experiment, and electrochemical test. Microstructure observation shows that the Mg_(97) Zn_(1)Y_(2)-1 wt.%Si C alloy is composed of α-Mg matrix, LPSO(Mg_(12) ZnY) phase and Si C phase. The hydrogen evolution and electrochemical test results reflect that the Mg_(97)Zn_(1)Y_(2)-1 wt.%SiC in 0.2 mol·L^(-1) Na Cl solution has the fastest corrosion rate, followed by Na_(2)SO_(4) and NaNO_(3) solutions, and that the charge-transfer resistance presents the contrary trend and decreases in turn.展开更多
We studied the corrosion characteristics of reinforcing bars in concrete under different corrosion conditions. The area-box (AB) value was used to classify the shape of pitting corrosion morphology in meso-scale, an...We studied the corrosion characteristics of reinforcing bars in concrete under different corrosion conditions. The area-box (AB) value was used to classify the shape of pitting corrosion morphology in meso-scale, and fractographs of reinforcing bars with different corrosion morphology were discussed in micro- and macro-scales. The results show that the existence of the tensile stress affects the corrosion characteristics of reinforcing bars. The pitting morphology and fractograph of reinforcing bars exhibit a statistical fractal feature. The linear regression model fits the relationship between fractal dimensions of corrosion morphology and fractal dimension of fractograph fairly well. Using fractal dimension as the characterization parameter can not only reflect the characteristics of pitting corrosion morphology in reinforcing bars, but also reveal the fracture feature of corroded reinforcing bars.展开更多
The stress corrosion of S355 steel in 3.5% NaCl solution under the different strain rates was analyzed with the slow strain rate test(SSRT), the stress corrosion cracking(SCC) behaviors of S355 steel under the dif...The stress corrosion of S355 steel in 3.5% NaCl solution under the different strain rates was analyzed with the slow strain rate test(SSRT), the stress corrosion cracking(SCC) behaviors of S355 steel under the different strain rates in the solution were investigated, and the fracture morphologies and compositions of corrosion products under the different strain rates were analyzed with scanning electron microscopy(SEM) and energy dispersive spectrometerry(EDS), respectively. The experimental results show that the SCC sensitivity index is the highest when the strain rate is 2×10-6, and the medium corrosion is the main reason resulting in the highest SCC sensitivity index. The SCC sensitivity index is the least when the strain rate is 5×10-6, and the stress is the main reason resulting in the stress corrosion. The SCC sensitivity index is the middle when the strain rate is 9×10-6, the interaction of stress and medium is the stress corrosion fracture mechanism.展开更多
The corrosion of reinforcement in the concrete will cause the effective cross-sectional area of reinforcement to be weakened and the performance of reinforcement to change and lead to the degradation of the bond behav...The corrosion of reinforcement in the concrete will cause the effective cross-sectional area of reinforcement to be weakened and the performance of reinforcement to change and lead to the degradation of the bond behavior between reinforcement and concrete,which can seriously affect the mechanical properties of the structural elements.Therefore,it is of great practical significance to accurately simulate the corrosion morphology and the corrosion products of reinforcement.This paper improves the previous cellular automata models and establishes a new cellular automata model framework for simulating the random pitting corrosion process of reinforcement in concrete.This model defines the detailed local evolution laws of material transformation,penetration and diffusion processes during the corrosion.Meanwhile,based on the spatial inhomogeneity of corrosion,three parameters are introduced into the model:The dissolution probability parameter p,the local corrosion space parameterλand the local corrosion probability parameterε,which establishes a parameterized model of corrosion probability.The research results show that the common steel reinforcement corrosion morphology can be obtained by adjusting the parameters.The volume expansion rate of the corrosion products is about 2,which is consistent with the relevant experimental research results.The cellular automata model in this paper can simulate the common steel reinforcement corrosion morphology and corrosion products in engineering.展开更多
基金Project(2008DFR60340)supported by the International Science and Technology Cooperation of ChinaProject(2008087)supported by Scientific Technological Project of Weihai,China。
文摘The corrosion process of copper in thermal flow system was investigated through the experimental bench.According to surface variation of samples during corrosion process,the surface model of specimen was build up based on Gaussian filter.The results show that the corrosion characterization of copper in thermal flow system is pitting corrosion.The morphology characterizations of metal corrosion process can be described using the proposed surface model.The generation and development of copper pitting process can be observed clearly.
基金Project supported by the Key Project of National Natural Science Foundation of China (50731007)the National High Technology Research and Development Program of China (2007AA03Z440)
文摘The morphology analysis and electrochemical method were used to study the corrosion behavior of LaFe11.6Si1.4 alloy of copper ion implantation. X-ray photoelectron spectroscopy (XPS) and atomic emission spectroscopy (AES) research results showed that a 15 nm-thick oxide film was formed on the surface of sample, and the copper content reached the highest value at 60 nm with a normal distribution. Immersion experiments indicated that the corrosion happened in the copper-poor zone firstly and a galvanic connection was formed among different zones on the surface due to the inhomogeneous distribution of copper. Electrochemical experiment results showed that the corrosion was serious when the ion acceleration voltage increased, and the high acceleration could reduce the thermodynamic performance of corrosion of LaFe11.6Si1.4 alloy.
基金Project (2011BAE22B01) supported by the National Key Technology R&D Program of China
文摘The corrosion behaviours of Mg-5Y-7Gd-1Nd-0.5Zr magnesium alloys prepared by as-casting and extrusion were investigated in 5% NaCl aqueous solution by immersion and electrochemical tests. The microstructure indicates the mean grain size of 15 μm for the extruded and 100 μm for the as-cast Mg-5Y-7Gd-1Nd-0.5Zr magnesium alloys. The corrosion morphology of as-cast sample shows pitting corrosion and little filiform corrosion, but that of the extruded sample shows pitting corrosion at the initial stage. The corrosion rate of extruded sample is higher than that of as-cast Mg-5Y-7Gd-1Nd-0.5Zr alloy according to the immersion test. The second phases containing RE acting as cathodes improve the corrosion properties. The corrosion potentials of as-cast and extruded Mg-5Y-7Gd-1Nd-0.5Zr alloys are -1.658 V and -1.591 V, respectively. The origins of the distinctive corrosion behavior of as-cast and extruded Mg-5Y-7Gd-1Nd-0.5Zr Mg alloys were discussed.
基金This work was supported by the financial support of the National Natural Science Foundation of China(No.41276074)National Research Program of China(No.2014CB643304).
文摘The corrosion behavior of Mg-8Li-3Zn-Al alloy was investigated in neutral 3.5%NaCl aqueous solution by morphology observation and electrochemical tests.The weight loss method was to measure the corrosion rate.The electrochemical results indicated that the corrosion resistance of Mg-8Li-3Zn-Al alloy in 3.5%NaCl solution is poorer than that in distilled water.The Cl-anion leads to the initiation and development of the corrosion pits.And the corrosion products are mainly Mg(OH)_(2).
文摘Experiments were performed to study the pitting corrosion morphology of 304 stainless steel exposed to FeCl 3 environments and SEM micrographs of the pitting corrosion morphology were obtained. The image processing technique combining with the fractal method was employed to analyze these pitting corrosion images and the self-similarity of pits morphology was observed. It indicates that fractal characteristics exist in pitting corrosion of 304 stainless steel. The self-similarity and complexity of the pitting morphology phenomenon were described in terms of fractal dimension which can also be an important parameter related to characterize pitting morphology qualitatively and quantitatively.
基金Projects(2011BAE22B01,2011BAE22B06)supported by the National Key Technology R&D Program,China
文摘This paper studied the influence of aging treatment on the corrosion behavior and mechanism of Mg-Y alloys with different Y content through corrosion mass loss test, electrochemical test and corrosion morphologies observation. Results show that the peak-aging times of Mg-(0.25, 2.5, 5, 8 and 15) Y alloys at 250 ℃ were 4, 6, 10, 12 and 16 h. The aging treatment reduced the corrosion resistance of Mg-Y alloys, and the corrosion resistance of Mg-Y alloys became worse with increasing of the aging time. The change magnitude of the open circuit potentials for Mg-(0.25, 2.5)Y alloys was greater than that of Mg-(5, 8 and 15)-Y alloys. The polarization curves of Mg (0.25, 2.5, 5, 8 and 15) Y alloys had the similar shape after aging treatment, and the slopes of the anodic branch were greater than those of the cathodic branches. After aging treatment, the corrosion modes of Mg-0.25Y and Mg-(2.5, 5, 8 and 15) Y alloys were uniform corrosion and pitting corrosion with small local deep corrosion.
基金Financially supported by the National Natural Science Foundation of China (51665012)the Jiangxi Province Science Foundation for Outstanding Scholarship (20171BCB23061,2018ACB21020)the Primary Research & Development Plan of Jiangxi Province (20192BBEL50019)。
文摘To explore the corrosion properties of magnesium alloys, the chemical behavior of a high strength Mg_(97)Zn_(1)Y_(2)-1 wt.%Si C alloy in different corrosion environments was studied. Three solutions of 0.2 mol·L^(-1) NaCl, Na_(2)SO_(4) and NaNO_(3) were selected as corrosion solutions. The microstructures, corrosion rate, corrosion potential, and mechanism were investigated qualitatively and quantitatively by optical microscopy(OM), scanning electron microscopy(SEM), immersion testing experiment, and electrochemical test. Microstructure observation shows that the Mg_(97) Zn_(1)Y_(2)-1 wt.%Si C alloy is composed of α-Mg matrix, LPSO(Mg_(12) ZnY) phase and Si C phase. The hydrogen evolution and electrochemical test results reflect that the Mg_(97)Zn_(1)Y_(2)-1 wt.%SiC in 0.2 mol·L^(-1) Na Cl solution has the fastest corrosion rate, followed by Na_(2)SO_(4) and NaNO_(3) solutions, and that the charge-transfer resistance presents the contrary trend and decreases in turn.
基金Funded by 973 Program(No.2009CB623200)National Natural Science Foundation of China(No.51008276)+1 种基金Ningbo Scientific and Technological Innovation Team(No.2011B81005)Ningbo Natural Science Foundation(No.2011A610075)
文摘We studied the corrosion characteristics of reinforcing bars in concrete under different corrosion conditions. The area-box (AB) value was used to classify the shape of pitting corrosion morphology in meso-scale, and fractographs of reinforcing bars with different corrosion morphology were discussed in micro- and macro-scales. The results show that the existence of the tensile stress affects the corrosion characteristics of reinforcing bars. The pitting morphology and fractograph of reinforcing bars exhibit a statistical fractal feature. The linear regression model fits the relationship between fractal dimensions of corrosion morphology and fractal dimension of fractograph fairly well. Using fractal dimension as the characterization parameter can not only reflect the characteristics of pitting corrosion morphology in reinforcing bars, but also reveal the fracture feature of corroded reinforcing bars.
基金Funded by the Key Research and Development Project of Jiangsu Province(BE2016052)
文摘The stress corrosion of S355 steel in 3.5% NaCl solution under the different strain rates was analyzed with the slow strain rate test(SSRT), the stress corrosion cracking(SCC) behaviors of S355 steel under the different strain rates in the solution were investigated, and the fracture morphologies and compositions of corrosion products under the different strain rates were analyzed with scanning electron microscopy(SEM) and energy dispersive spectrometerry(EDS), respectively. The experimental results show that the SCC sensitivity index is the highest when the strain rate is 2×10-6, and the medium corrosion is the main reason resulting in the highest SCC sensitivity index. The SCC sensitivity index is the least when the strain rate is 5×10-6, and the stress is the main reason resulting in the stress corrosion. The SCC sensitivity index is the middle when the strain rate is 9×10-6, the interaction of stress and medium is the stress corrosion fracture mechanism.
基金The works described in this paper are substantially supported by the grant from National Natural Science Foundation of China(Grant No.51678135)Natural Science Foundation of Jiangsu Province(No.BK20171350)Six Talent Peak Projects in Jiangsu Province(JNHB-007),which are gratefully acknowledged.
文摘The corrosion of reinforcement in the concrete will cause the effective cross-sectional area of reinforcement to be weakened and the performance of reinforcement to change and lead to the degradation of the bond behavior between reinforcement and concrete,which can seriously affect the mechanical properties of the structural elements.Therefore,it is of great practical significance to accurately simulate the corrosion morphology and the corrosion products of reinforcement.This paper improves the previous cellular automata models and establishes a new cellular automata model framework for simulating the random pitting corrosion process of reinforcement in concrete.This model defines the detailed local evolution laws of material transformation,penetration and diffusion processes during the corrosion.Meanwhile,based on the spatial inhomogeneity of corrosion,three parameters are introduced into the model:The dissolution probability parameter p,the local corrosion space parameterλand the local corrosion probability parameterε,which establishes a parameterized model of corrosion probability.The research results show that the common steel reinforcement corrosion morphology can be obtained by adjusting the parameters.The volume expansion rate of the corrosion products is about 2,which is consistent with the relevant experimental research results.The cellular automata model in this paper can simulate the common steel reinforcement corrosion morphology and corrosion products in engineering.