苯并三唑对退役核设施用钢1Cr18Ni9Ti在化学清洗中的缓蚀行为

Corrosion Inhibition Behavior of Benzotriazole for 1Cr18Ni9Ti as Nuclear Decommissioning Steel in Chemical Cleaning Agent

目前,国内外对退役核设施破坏性清洗的缓蚀机理研究少有报道。通过失重法、金相及电子扫描探针观测,电化学阻抗图谱测试,研究了清洗剂HK-1(10%HNO3+0.5%KMnO4)中加入苯并三唑对核退役用材1Cr18Ni9Ti不锈钢在清洗去除放射性元素时的腐蚀行为。结果表明:在HK-1中,随着苯并三唑浓度的提高,1Cr18Ni9Ti不锈钢的容抗弧增大,电极耐蚀性能增强,并且发生了阻抗谱中的"退化"现象;随苯并三唑浓度升高、清洗腐蚀速度下降,缓蚀效率上升,苯并三唑浓度为0.20%时,腐蚀失重低于0.07g/(m2.h),缓蚀效率大于90%,苯并三唑浓度为0.50%时,缓蚀效率高达98.78%;苯并三唑在金属表面形成一层吸附膜,降低了金属表面的粗糙度,有效地抑制了其晶间腐蚀,但吸附膜稳定性较差,易发生脱附。

The corrosion inhibition behavior of benzotriazole (C6H5N3) for 1Cr18Ni9Ti stainless steel used in decommissioned nuclear facilities was investigated based on weight loss test as well as observation with metallographic microscope and scanning electron probe plus measurement of electrochemical impedance spectrum. The corrosion inhibition effect of C6H5N3 was examined in relation to the removal of radioactive elements in the stainless steel by rinsing with detergent HK-1 consisting of 10% HNO3 and 0.5% KMnO4. Results show that the capacitance arc of the stainless steel in HK-1 increases with increasing concentration of C6H5N3, accompanied by increase of corrosion resistance of the electrode and occurrence of degradation phenomenon on the electrochemical impedance spectrum. Besides, with increasing concentration of C6H5N3, the corrosion rate of the steel subjected to cleaning in HK-1 decreased, and the corrosion inhibition efficiency rose. When the concentration of C6H5N3 was 0.20%, corrosion-induced weight loss of the stainless steel was below 0.07 g/(m2·h), and the corrosion inhibition efficiency was above 90%. At an increased C6H5N3 concentration of 0.50%, the corrosion inhibition efficiency was above 98.78%. Benzotriazole was able to form adsorption film on the surface of the stainless steel, resulting in decreased surface roughness and effectively retarding intergranular corrosion. However, the adsorbed film of benzotriazole had poor stability and was liable to desorption.