NaNO2对20SiMn低合金钢在3％NaCl溶液中空蚀损伤的缓蚀作用

利用磁致伸缩空蚀实验机研究了20SiMn低合金钢在3%NaCl和3%NaCl＋NaNO2溶液中的空蚀行为.测量了静态和空蚀条件下的腐蚀电位变化、电化学阻抗谱和极化曲线.结果表明：NaNO2通过抑制腐蚀与空蚀间的交互作用，对20SiMn低合金钢在3%NaCl溶液中的空蚀损伤有良好的抑制作用，浓度为1%的NaNO2的缓蚀效率达到802%.添加NaNO2对20SiMn低合金钢在3%NaCl溶液中的电化学行为有显著影响.在3%NaCl溶液中，自腐蚀电位、线性极化电阻都随空蚀进行而逐渐负移和减小.与此相反，添加NaNO2后，20SiMn的自腐蚀电位、线性极化电阻都随空蚀的进行而逐渐正移和增大.3%NaCl+1%NaNO2溶液中的电化学阻抗谱特征与空蚀表面形貌的变化有较好的对应关系.

INHIBITION OF NaNO2 ON CAVITATION CORROSION OF 20SiMn LOW ALLOY STEEL IN 3%NaCl SOLUTION

The cavitation corrosion behavior of 20SiMn low alloy steel in 3% NaCl solution with or without sodium nitrite was investigated by using a magnetostrictive-induced cavitation facility.The polarization curves and electrochemical impedance spectroscopy (EIS) under quiescent and cavitating conditions were measured.The results showed that cavitation damage of 20SiMn low alloy steel could be inhibited by NaNO 2 through suppression of the synergism between corrosion and cavitation.With a given concentration of 1% NaNO 2,its inhibition efficiency under cavitating conditions was 80.2%.The addition of NaNO 2 strongly affected the electrochemical corrosion behavior of 20SiMn low alloy steel in 3% NaCl solution.The free corrosion potential and polarization resistance decreased with cavitation time in 3% NaCl solution.Conversely,with the addition of NaNO 2,the free corrosion potential and polarization resistance increase with cavitation time.The characteristic of EIS was in accordance with the morphologies of cavitated surface of 20SiMn low alloy steel in 3%NaCl+1%NaNO 2.