Soil resistivity is one of the key indicators of the corrosive classification assessment on metal materials in soil environment. This paper presents variance characters of various quantity of soil resistivity samples ...Soil resistivity is one of the key indicators of the corrosive classification assessment on metal materials in soil environment. This paper presents variance characters of various quantity of soil resistivity samples data based on the semi-variance function methods of Geo-statistical Analysis by analyzing the regional soil resistivity sampling data in Daqing area. Furthermore, the variance of the soil resistivity as well as entire soil circumstance due to different sampling amounts are also analyzed and compared by means of using the characteristic parameters of the semi-variance function. In addition, this work also studied the rational sampling quantities according to various measurement errors required and evaluated the local soil corrosivity on carbon steel based on the actual measuring data in this area.展开更多
The effects of bentonite content on the corrosion behavior of low carbon steel in 5 mM NaHCO3+ 1 mM NaCl + 1 mM Na2SO4 solution were investigated by electrochemical measurements combined with X-ray diffraction(XRD) an...The effects of bentonite content on the corrosion behavior of low carbon steel in 5 mM NaHCO3+ 1 mM NaCl + 1 mM Na2SO4 solution were investigated by electrochemical measurements combined with X-ray diffraction(XRD) and scanning electron microscopy(SEM). In the initial immersion stage, the cathodic process of low carbon steel corrosion was dominated by the reduction of dissolved oxygen, while it transformed to the reduction of ferric corrosion products with the immersion time. The presence of bentonite colloids could suppress the cathodic reduction of oxygen due to their barrier effect on the diffusion of oxygen. However, the barrier performance of bentonite layer was gradually deteriorated due to the coagulation and separation of bentonite colloids caused by the charge neutralization of iron corrosion products dissolved from the steel substrate. More bentonite colloids could maintain the barrier effect for a long time before it was deteriorated by the accumulation of corrosion products. Conversely,it could lose the performance completely, and the corrosion behavior of low carbon steel reverted to the same as that in the blank solution.展开更多
The corrosion behavior of low carbon steel in 0.1 M NaHCO_3+ 0.1 M NaCl solution with different dissolved oxygen concentrations was investigated with gravimetric tests and electrochemical measurements.Results show tha...The corrosion behavior of low carbon steel in 0.1 M NaHCO_3+ 0.1 M NaCl solution with different dissolved oxygen concentrations was investigated with gravimetric tests and electrochemical measurements.Results show that the corrosion mass loss of steel is remarkably increased with the addition of chloride ion. In the initial stage, the carbon steel tends to active dissolution due to the dissolution effect of chloride ion on the oxide film; as a result, the corrosion potential maintains as low values. With the immersion time going by, the corrosion potential of the steel is promoted as a result of the accumulation of the corrosion products. However, the rust layer is loose and porous due to the deteriorating effect of chloride ion, which decreases the reduction resistance of oxygen. Meanwhile, the porous rust layer could be repaired by the depolarization of oxygen. Under the synergistic effect of chloride ion and oxygen, the corrosion of the steel is accelerated during the repeated process of dissolution and reparation of the oxide film.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 media展开更多
To improve the corrosion resistance of steels for grounding grids, a low-carbon Cr micro-alloyed steel was developed (C 1 steel), and corrosion behavior of Q235 steel and newly developed C1 steel in simulated acidic...To improve the corrosion resistance of steels for grounding grids, a low-carbon Cr micro-alloyed steel was developed (C 1 steel), and corrosion behavior of Q235 steel and newly developed C1 steel in simulated acidic soil was investigated. The corrosion rate was evaluated with the mass loss measurements, while the corrosion morphology of surface and cross section of rust layer was observed by scanning electron microscopy. The corrosion products were analyzed by energy- dispersive X-ray spectrometry, X-ray diffraction and X-ray photoelectron spectroscopy, and the polarization curve was measured using potentiodynamic polarization method. Results indicated that C 1 steel displayed good corrosion resistance in the simulated acidic soil, of which the corrosion rate was only 30% of that of Q235 steel after corrosion for 360 h. The analysis of rust layer showed that lower carbon content in steel could reduce the tendency of micro cell corrosion and appropriate amount of chromium could improve the corrosion potential of metal matrix. Moreover, the analysis of X-ray photoelectron spectroscopy revealed that the chromium enriched in inner rust layer of C1 steel existed mainly in the form of Fe2CrO4, which facilitated the formation of Cr-goethite and improved the protection of corrosion products.展开更多
The influence of pH and metallographic structure on the corrosion behavior of copper-drawn steel is studied with the simulated system.The effect of pH on the corrosion behavior of copper-drawn steel has been investiga...The influence of pH and metallographic structure on the corrosion behavior of copper-drawn steel is studied with the simulated system.The effect of pH on the corrosion behavior of copper-drawn steel has been investigated using open-circuit potential,potentiodynamic polarization,galvanic current measurement,scanning electron microscopy and scanning vibrating electrode technique techniques.The steel is corroded as anode,while the corrosion of copper plate is protected as cathode.All the results revealed that pH and metallographic structure had a significant influence on the corrosion behavior of copper-drawn steel.With the decrease in pH value from 6 to 2.4,the corrosion rate of copper-drawn steel galvanic couple(Cu-Fe GC)obviously increased in the simulated solution of acidic red soil.The electric field formed by the Cu-Fe GC changes the direction of ion migration between the copper and drawn steel electrodes,which impacts the composition and microstructure of corrosion products formed on the electrode surface.展开更多
基金support of the National Natural Science Foundation of China (No.50971016)support of the National R&D Infrastructure and Facility Development Program of China (2005DKA10400)
文摘Soil resistivity is one of the key indicators of the corrosive classification assessment on metal materials in soil environment. This paper presents variance characters of various quantity of soil resistivity samples data based on the semi-variance function methods of Geo-statistical Analysis by analyzing the regional soil resistivity sampling data in Daqing area. Furthermore, the variance of the soil resistivity as well as entire soil circumstance due to different sampling amounts are also analyzed and compared by means of using the characteristic parameters of the semi-variance function. In addition, this work also studied the rational sampling quantities according to various measurement errors required and evaluated the local soil corrosivity on carbon steel based on the actual measuring data in this area.
基金financially supported by the National Natural Science Foundation of China (Nos. 51701222, U1867216 and 51471175)。
文摘The effects of bentonite content on the corrosion behavior of low carbon steel in 5 mM NaHCO3+ 1 mM NaCl + 1 mM Na2SO4 solution were investigated by electrochemical measurements combined with X-ray diffraction(XRD) and scanning electron microscopy(SEM). In the initial immersion stage, the cathodic process of low carbon steel corrosion was dominated by the reduction of dissolved oxygen, while it transformed to the reduction of ferric corrosion products with the immersion time. The presence of bentonite colloids could suppress the cathodic reduction of oxygen due to their barrier effect on the diffusion of oxygen. However, the barrier performance of bentonite layer was gradually deteriorated due to the coagulation and separation of bentonite colloids caused by the charge neutralization of iron corrosion products dissolved from the steel substrate. More bentonite colloids could maintain the barrier effect for a long time before it was deteriorated by the accumulation of corrosion products. Conversely,it could lose the performance completely, and the corrosion behavior of low carbon steel reverted to the same as that in the blank solution.
基金supported by the National Natural Science Foundation of China (No.51471175)
文摘The corrosion behavior of low carbon steel in 0.1 M NaHCO_3+ 0.1 M NaCl solution with different dissolved oxygen concentrations was investigated with gravimetric tests and electrochemical measurements.Results show that the corrosion mass loss of steel is remarkably increased with the addition of chloride ion. In the initial stage, the carbon steel tends to active dissolution due to the dissolution effect of chloride ion on the oxide film; as a result, the corrosion potential maintains as low values. With the immersion time going by, the corrosion potential of the steel is promoted as a result of the accumulation of the corrosion products. However, the rust layer is loose and porous due to the deteriorating effect of chloride ion, which decreases the reduction resistance of oxygen. Meanwhile, the porous rust layer could be repaired by the depolarization of oxygen. Under the synergistic effect of chloride ion and oxygen, the corrosion of the steel is accelerated during the repeated process of dissolution and reparation of the oxide film.
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 media
文摘To improve the corrosion resistance of steels for grounding grids, a low-carbon Cr micro-alloyed steel was developed (C 1 steel), and corrosion behavior of Q235 steel and newly developed C1 steel in simulated acidic soil was investigated. The corrosion rate was evaluated with the mass loss measurements, while the corrosion morphology of surface and cross section of rust layer was observed by scanning electron microscopy. The corrosion products were analyzed by energy- dispersive X-ray spectrometry, X-ray diffraction and X-ray photoelectron spectroscopy, and the polarization curve was measured using potentiodynamic polarization method. Results indicated that C 1 steel displayed good corrosion resistance in the simulated acidic soil, of which the corrosion rate was only 30% of that of Q235 steel after corrosion for 360 h. The analysis of rust layer showed that lower carbon content in steel could reduce the tendency of micro cell corrosion and appropriate amount of chromium could improve the corrosion potential of metal matrix. Moreover, the analysis of X-ray photoelectron spectroscopy revealed that the chromium enriched in inner rust layer of C1 steel existed mainly in the form of Fe2CrO4, which facilitated the formation of Cr-goethite and improved the protection of corrosion products.
基金financially supported by the Science and Technology Commission of Shanghai Municipality(No.19DZ2271100)。
文摘The influence of pH and metallographic structure on the corrosion behavior of copper-drawn steel is studied with the simulated system.The effect of pH on the corrosion behavior of copper-drawn steel has been investigated using open-circuit potential,potentiodynamic polarization,galvanic current measurement,scanning electron microscopy and scanning vibrating electrode technique techniques.The steel is corroded as anode,while the corrosion of copper plate is protected as cathode.All the results revealed that pH and metallographic structure had a significant influence on the corrosion behavior of copper-drawn steel.With the decrease in pH value from 6 to 2.4,the corrosion rate of copper-drawn steel galvanic couple(Cu-Fe GC)obviously increased in the simulated solution of acidic red soil.The electric field formed by the Cu-Fe GC changes the direction of ion migration between the copper and drawn steel electrodes,which impacts the composition and microstructure of corrosion products formed on the electrode surface.