碱性溶液中阴极极化对模拟铸铁文物局部腐蚀闭塞区化学和电化学状态的影响

采用模拟闭塞电池恒电流法研究在碱性溶液中阴极极化对模拟铸铁文物局部腐蚀闭塞区内溶液化学和电化学状态的影响.结果表明：对试样通入阴极电流后,闭塞区内溶液的pH值随着通电时间的延长及阴极电流密度的增大而升高;氯离子向闭塞区外迁移,迁移率和迁移速率随时间的延长和电流密度的增大而增高.由于Cl^-的迁出及外部OH-的迁入,闭塞区内的腐蚀受到抑制.通阴极电流能加速闭塞区内Cl^-的迁出,比铸铁文物通常采用的碱性溶液浸泡脱氯法更为有效,是一种快速的电化学脱氯方法.

EFFECT OF CATHODIC POLARIZATION ON CHEMICAL AND ELECTROCHEMICAL STATES INSIDE OCCLUDED CELLS OF LOCALIZED CORROSION OF CAST IRON IN ALKALINE SOLUTION

A simulated galvanostatic occluded cell was used to investigate the effect of cathodic polarization on chemical and electrochemical states inside occluded cell(OC) of localized corrosion for cast iron in alkaline solution.It has been found that as the cathodic current passes through the cell,the pH value of the OC solution rises with prolonging of time and rising of current density;the rate of Cl~-migrating out from the OC also rises with prolonging of time and rising of current density.Because of Cl~-migrating out from OC and OH~-immigrating into OC,the localized corrosion was retarded.Passing cathodic polarization in alkaline solution can make Cl~-migrating more quickly,it is more efficiency than the cast iron dipping in alkaline solution(no cathodic polarization).