采用模拟闭塞电池法和模拟闭塞区溶液法，测定了0Cr18Ni9 奥氏体不锈钢(304 SS)在0.5 mol·L-1 NaCl(pH=7)以及A3钢在0.01 mol·L-1 NaCl(pH=12)两种体系，孔蚀的不同阶段孔内外间电流的换向电位ET.结果表明，E T值随闭塞区溶液组成的变化而变化，但存在一个范围.将304不锈钢的ET值与用 孔蚀滞后环法在不同扫描速度，不同回扫电流时所测得的孔蚀保护电位EP值作比较， 发现EP值范围处于ET值范围之内.ET值可以为孔蚀阴极保护电位参数的 确定提供依据.
Two methodssimulated occluded cell and simulated occluded solutionhave been developed to determine the protection potential aga inst pitting of A3 steel and 0Cr18Ni9 stainless steel.They are based on the theo ry that the pitting protection potential(EP) is actually the transition po tential of the direction of current between the occluded cell and the external s urface(ET).The ET of 304 SS in 0.5 mol·L-1 NaCl solution is in the range of 220 mV to 440 mV(SCE), the ET of A3 steel in 0.01 mol ·L-1 NaCl solution(pH=12) is in the range of 390～670 mV, the lowest of which can be considered as cathode protection potential(EP).The E P of 304 SS determined with “cyclic” potentiodynamic polarization method is included in the ET with above methods.As for electrochemical protection ag ainst pitting, if the potential of the external surface is controlled below the EP,the activepassive transition will occur inside the occluded cell, so the pitting will be stifled.
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