The electrochemical behavior of metallic passive film on rebar in concrete is characterized by its semiconductive nature. The charge distribution at the interface between a semiconductor and an electrolyte is often de...The electrochemical behavior of metallic passive film on rebar in concrete is characterized by its semiconductive nature. The charge distribution at the interface between a semiconductor and an electrolyte is often determined by measuring the capacitance of the space-charge layer （Csc） as a function of the electrode potential （E）. When the space charge-layer serves as the depletion layer, the relation of Csc^-2 vs E resembles a Mott-Schottky plot （M-S plot）. The semiconductive properties of the passive film on rebar in concrete were analyzed with M-S plots to study the effect of chloride ions and mineral admixtures on rebar passive films. Some rebar electrodes were immersed in simulated concrete pore solutions, while others were embedded in concrete with/without mineral admixtures. In saturated Ca（OH）, solutions, the relation of Csc^-2-E of rebar electrodes shows linear MottSchottky relationship indicating that the passive film on rebar is a highly disordered n-type semiconductor, with donor density （ND） in the order of 10^26m^-3. After adding chloride ions （Cl wt%〈0.2%） in system solutions, the M-S plot slopes significantly decreased and ND increased, suggesting that chloride ion will cause passive film corrosion and breakdown. The M-S plots of the passive film on rebar electrodes embedded in concrete were similar to those immersed in simulated system solution. However, ND of those in concrete with mineral admixtures tended to be a little smaller, indicating that introducing proper quantity admixtures into concrete could make the rebar passive film have a thicker space-charge layer and therefore a thicker passive film layer.展开更多
A cerium film was prepared on the surface of rebar by chemical conversion method to enhance its corrosion resistance.The film in the simulated concrete pore solution was measured by electrochemical method,transmission...A cerium film was prepared on the surface of rebar by chemical conversion method to enhance its corrosion resistance.The film in the simulated concrete pore solution was measured by electrochemical method,transmission electron microscope(TEM)and X-ray photoelectron spectroscopy(XPS).The effect of temperature on film formation was studied,and the optimum temperature was determined at 35℃.The film produced by too high formation temperature has more defects,resulting in the lower corrosion resistance.The Ce film resistance increased with time evolution until 800 h,then decreased and stabilized.The Ce film layer has a double-layer film structure,the upper layer is an oxide of cerium,and the underlayer is an oxide of iron.Results revealed that after being immersed in the simulated concrete pore solution,the corrosion resistance of the Ce film was enhanced by self-densification.展开更多
基金Project (No. 502019) supported by the Natural Science Foundationof Zhejiang Province, China
文摘The electrochemical behavior of metallic passive film on rebar in concrete is characterized by its semiconductive nature. The charge distribution at the interface between a semiconductor and an electrolyte is often determined by measuring the capacitance of the space-charge layer （Csc） as a function of the electrode potential （E）. When the space charge-layer serves as the depletion layer, the relation of Csc^-2 vs E resembles a Mott-Schottky plot （M-S plot）. The semiconductive properties of the passive film on rebar in concrete were analyzed with M-S plots to study the effect of chloride ions and mineral admixtures on rebar passive films. Some rebar electrodes were immersed in simulated concrete pore solutions, while others were embedded in concrete with/without mineral admixtures. In saturated Ca（OH）, solutions, the relation of Csc^-2-E of rebar electrodes shows linear MottSchottky relationship indicating that the passive film on rebar is a highly disordered n-type semiconductor, with donor density （ND） in the order of 10^26m^-3. After adding chloride ions （Cl wt%〈0.2%） in system solutions, the M-S plot slopes significantly decreased and ND increased, suggesting that chloride ion will cause passive film corrosion and breakdown. The M-S plots of the passive film on rebar electrodes embedded in concrete were similar to those immersed in simulated system solution. However, ND of those in concrete with mineral admixtures tended to be a little smaller, indicating that introducing proper quantity admixtures into concrete could make the rebar passive film have a thicker space-charge layer and therefore a thicker passive film layer.
基金financially supported by the National Natural Science Foundation of China(Nos.51771061 and 51571067)the National Basic Research Program of China(No.2014CB643301)+2 种基金the Natural Science Foundation of Heilongjiang Province,China(No.E2016022)the Fundamental Research Founds for the Central Universities(No.HEUCFG201838)the Key Laboratory of Superlight Materials and Surface Technology(Harbin Engineering University)。
文摘A cerium film was prepared on the surface of rebar by chemical conversion method to enhance its corrosion resistance.The film in the simulated concrete pore solution was measured by electrochemical method,transmission electron microscope(TEM)and X-ray photoelectron spectroscopy(XPS).The effect of temperature on film formation was studied,and the optimum temperature was determined at 35℃.The film produced by too high formation temperature has more defects,resulting in the lower corrosion resistance.The Ce film resistance increased with time evolution until 800 h,then decreased and stabilized.The Ce film layer has a double-layer film structure,the upper layer is an oxide of cerium,and the underlayer is an oxide of iron.Results revealed that after being immersed in the simulated concrete pore solution,the corrosion resistance of the Ce film was enhanced by self-densification.
