碳化对模拟混凝土孔溶液中HRB335钢腐蚀行为的影响

INFLUENCE OF CARBONATION ON THE CORROSION PERFORMANCE OF STEEL HRB335 IN SIMULATED CONCRETE PORE SOLUTION

应用电化学阻抗谱、循环伏安与动电位极化等方法研究了碳化后模拟混凝土孔溶液pH值的变化对钢筋腐蚀电化学行为的影响.结果表明,随着pH值的下降钢筋表面钝化膜的稳定性与耐蚀性不同程度地降低.当模拟液pH值为12.5与11.5时,钝化膜的稳定性处于因pH值降低导致的钝化膜溶解与表面沉积物CaCO_3或含钙氧化物CaFe_2O_4等耐蚀效应的动态平衡过程.当pH值继续下降(pH=10.5,10.0)时,钝化膜逐渐失稳破坏,均匀的活化腐蚀出现.

Electrochemical impedance spectroscopy, cyclic voltammetry and potentiodynamic polarization were used to investigate the effect of the decrease in pH values of simulated concrete pore （SCP） solutions due to carbonation on the corrosion of steel HRB335. The results indicated that the stability and corrosion inhibition of passive film on the steel surface decrease with decreasing pH value of SCP solutions. In SCP solutions with pH values of 12.5 and 11.5, the stability of passive film is in a competitive balance, the competition results from the dissolution of passive film due to the decreasing pH and the protective effect of calcium-iron containing protective layer CaFe2O4 or deposit CaCO3 formed on the steel surface. When the pH value decreased unceasingly （pH=10.5, 10.0）, the stability of passive film decreased gradually, and the active uniform corrosion occurred on the steel surface.