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利用Kelvin探针参比电极技术和电化学阻抗方法研究了不锈钢在不同厚度NaCl薄液膜下的腐蚀行为.结果表明:在0.35%NaCl液膜厚度7~90μm范围内,随着液层厚度的增大,不锈钢在薄液膜下腐蚀的氧扩散控制特征越显著,而且氧还原反应极限电流逐渐降低;3.5%NaCl薄液膜下阻抗测得的溶液电阻随着液膜增厚而首先迅速降低然后趋于平稳;在液层较厚时(425~120μm)随着液层厚度的减小,腐蚀速度受氧扩散控制逐渐增大;液层厚度减薄至40~120μm区间,由于阳极反应受抑制和阴极反应加速的共同影响腐蚀速度会出现极小值;液层厚度非常薄(20μm以下)时由于电流分布不均匀抑制了氧还原,腐蚀速度很低.
The corrosion behavior of stainless steel under different thicknesses of thin film of NaCl was investigated by Kelvin probe reference electrode technique and electrochemical impedance spectroscopy. The results show that with the thickness of liquid layer of 0.35% NaCl in the range of 7 ~ 90μm, The more obvious the oxygen diffusion control characteristic of the corrosion of stainless steel under the thin liquid membrane, and the reduction current of oxygen reduction reaction gradually decreases; the resistance of the solution measured under the 3.5% NaCl thin liquid membrane first decreases rapidly with the thickening of the liquid membrane And then tends to be stable. When the thickness of the liquid layer is thick (425-120μm), the corrosion rate gradually increases with the diffusion of oxygen as the thickness of the liquid layer decreases. The thickness of the liquid layer is reduced to 40-120μm. Since the anode reaction is affected The combined effect of suppression and acceleration of the cathode reaction has a minimal value of corrosion rate. When the thickness of the liquid layer is very thin (less than 20 μm), the oxygen reduction is suppressed due to the uneven current distribution, and the etching rate is very low.