The initial corrosion evolution of marine structural steel in tidal zone is studied using wire beam electrode(WBE).The electrochemical experiment results show that the WBE in the high and middle tidal zones are in the...The initial corrosion evolution of marine structural steel in tidal zone is studied using wire beam electrode(WBE).The electrochemical experiment results show that the WBE in the high and middle tidal zones are in the anodic dissolution state for less time than that in the low tidal and immersion zones.The fitting results of WBE experiment provide the boundary conditions for the partitioned cellular automata(PCA)model,which is adopted to simulate the initial corrosion evolutions of steel in the tidal zone.The proposed independent variable of the electrolyte concentration(ρ),corrosion probability(P_(c)),passivation probability(P_(p)),and movement direction probability(P_(m))on the corrosion behavior of steel are studied.The calculated results demonstrate that ρ and P_(m)can well characterize the corrosion evolutions of the steel in ocean tidal zones.This model is effective in predicting the corrosion evolution of marine structural steel in tidal zone.It provides a new method for predicting the corrosion evolution of marine structural steel in tidal zone.展开更多
The current distributions over carbon steel under iron red alkyd primer exposed to 3.5% sodium chloride solution were mapped using the wire beam electrode （WBE）. The electrochemical impedance spectroscopy （EIS） of...The current distributions over carbon steel under iron red alkyd primer exposed to 3.5% sodium chloride solution were mapped using the wire beam electrode （WBE）. The electrochemical impedance spectroscopy （EIS） of the WBE was carded out to analyze the performance of coating delamination and corrosion behavior of carbon steel beneath defective coating. The EIS data revealed that protective capability of coating decreased with immersion time and the degree of cathodic delamination showed a rapid rise. The current density distribution of WBE indicated that cathodic sites was located at the defect at the beginning of immersion and gradually spread into the intact coating. The cathodic regions were distinguished from the anodic area and distributed over the WBE. The changes of cathodic sites could reflect the deterioration process of defective coating. The cathodic area ratio was a more useful parameter than the cathodic delamination degree to evaluate the coating cathodic delamination. The polarity reversals of electrodes at the defect and beneath coating were observed. A simple discussion of relationship between the blister and the polarity reversal was made from a standpoint of electrochemical distribution. WBE method was able to map and record the changes of local cathodic sites beneath defective coating in real time, which could provide more detailed information about the local degradation of coating.展开更多
The effect of in-situ local damage of uniform porous corrosion products on the localised corrosion of carbon steel is investigated using the wire beam electrode technique(WBE)combined with morphology characterisation ...The effect of in-situ local damage of uniform porous corrosion products on the localised corrosion of carbon steel is investigated using the wire beam electrode technique(WBE)combined with morphology characterisation and electrochemical tests.The WBE measurements demonstrate that the localised corrosion is enhanced by the in-situ local removal of porous corrosion products,supported by the morphology characterisation and electrochemical tests.The enhanced localised corrosion does not originate from the damaged wire in WBE where the corrosion products are removed but from the other undamaged wires,which is reported for the first time.A mechanism is proposed that the intensive anodic polarisation effect of the damaged wire on the undamaged wires could account for the enhanced localised corrosion,which is due to the protective corrosion products newly formed on the damaged surface and the increase in the potential of damaged wire.展开更多
The study aimed to explore the cathodic protection of the defect areas of 75 wt.%zinc-rich coatings(ZRCs)under immersion and atmospheric thin liquid film conditions using a wire beam electrode(WBE).Besides,electrochem...The study aimed to explore the cathodic protection of the defect areas of 75 wt.%zinc-rich coatings(ZRCs)under immersion and atmospheric thin liquid film conditions using a wire beam electrode(WBE).Besides,electrochemical impedance spectroscopy,scanning electron microscopy,and surface morphology analysis were used.Under both experimental conditions,high ZRCs content polarised the entire electrode to the protective potential range,thereby reversing the polarity of the defect area steel substrate to cathodic to prevent corrosion.The higher concentration of dissolved oxygen in the surface liquid film and coating activated the zinc powder faster and provided a higher cathodic protection current for the defect area under the atmospheric liquid film condition.Therefore,WBE corrosion potential shifted more negative under the atmospheric liquid film condition,thereby conveying longer-lasting cathodic protection and reducing the corrosion rate of the defect area steel substrate.Compared with the traditional sheet electrode,WBE can provide the current distribution and change information of cathodic protection at the local defects on the ZRCs surface,thereby providing a reliable test and a method for evaluating heterogeneous corrosion and cathodic protection.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51879292 and 51525903)the Guangdong International Science and Technology Cooperation Programme(No.2019A050510020)the 173 Project(No.2020-JCJQ-ZD-233-03),which cooperating with Northeastern University
文摘The initial corrosion evolution of marine structural steel in tidal zone is studied using wire beam electrode(WBE).The electrochemical experiment results show that the WBE in the high and middle tidal zones are in the anodic dissolution state for less time than that in the low tidal and immersion zones.The fitting results of WBE experiment provide the boundary conditions for the partitioned cellular automata(PCA)model,which is adopted to simulate the initial corrosion evolutions of steel in the tidal zone.The proposed independent variable of the electrolyte concentration(ρ),corrosion probability(P_(c)),passivation probability(P_(p)),and movement direction probability(P_(m))on the corrosion behavior of steel are studied.The calculated results demonstrate that ρ and P_(m)can well characterize the corrosion evolutions of the steel in ocean tidal zones.This model is effective in predicting the corrosion evolution of marine structural steel in tidal zone.It provides a new method for predicting the corrosion evolution of marine structural steel in tidal zone.
基金supported by the National Natural Science Foundation of China (Grant No. 51131005)
文摘The current distributions over carbon steel under iron red alkyd primer exposed to 3.5% sodium chloride solution were mapped using the wire beam electrode （WBE）. The electrochemical impedance spectroscopy （EIS） of the WBE was carded out to analyze the performance of coating delamination and corrosion behavior of carbon steel beneath defective coating. The EIS data revealed that protective capability of coating decreased with immersion time and the degree of cathodic delamination showed a rapid rise. The current density distribution of WBE indicated that cathodic sites was located at the defect at the beginning of immersion and gradually spread into the intact coating. The cathodic regions were distinguished from the anodic area and distributed over the WBE. The changes of cathodic sites could reflect the deterioration process of defective coating. The cathodic area ratio was a more useful parameter than the cathodic delamination degree to evaluate the coating cathodic delamination. The polarity reversals of electrodes at the defect and beneath coating were observed. A simple discussion of relationship between the blister and the polarity reversal was made from a standpoint of electrochemical distribution. WBE method was able to map and record the changes of local cathodic sites beneath defective coating in real time, which could provide more detailed information about the local degradation of coating.
基金the Opening Project of Material Corrosion and Protection Key Laboratory of Sichuan Province(No.2017CL18)。
文摘The effect of in-situ local damage of uniform porous corrosion products on the localised corrosion of carbon steel is investigated using the wire beam electrode technique(WBE)combined with morphology characterisation and electrochemical tests.The WBE measurements demonstrate that the localised corrosion is enhanced by the in-situ local removal of porous corrosion products,supported by the morphology characterisation and electrochemical tests.The enhanced localised corrosion does not originate from the damaged wire in WBE where the corrosion products are removed but from the other undamaged wires,which is reported for the first time.A mechanism is proposed that the intensive anodic polarisation effect of the damaged wire on the undamaged wires could account for the enhanced localised corrosion,which is due to the protective corrosion products newly formed on the damaged surface and the increase in the potential of damaged wire.
基金financially supported by the National Natural Science Foundation of China(Nos.21203034 and 51771057)the GF Research and Cultivation Project of Sun Yat-sen University(No.76110–18843406)the National Science and Technology Resources Investigation Program of China(No.2019FY101400)
文摘The study aimed to explore the cathodic protection of the defect areas of 75 wt.%zinc-rich coatings(ZRCs)under immersion and atmospheric thin liquid film conditions using a wire beam electrode(WBE).Besides,electrochemical impedance spectroscopy,scanning electron microscopy,and surface morphology analysis were used.Under both experimental conditions,high ZRCs content polarised the entire electrode to the protective potential range,thereby reversing the polarity of the defect area steel substrate to cathodic to prevent corrosion.The higher concentration of dissolved oxygen in the surface liquid film and coating activated the zinc powder faster and provided a higher cathodic protection current for the defect area under the atmospheric liquid film condition.Therefore,WBE corrosion potential shifted more negative under the atmospheric liquid film condition,thereby conveying longer-lasting cathodic protection and reducing the corrosion rate of the defect area steel substrate.Compared with the traditional sheet electrode,WBE can provide the current distribution and change information of cathodic protection at the local defects on the ZRCs surface,thereby providing a reliable test and a method for evaluating heterogeneous corrosion and cathodic protection.
