几种缓蚀剂对膨润土中16MnR钢的缓蚀作用

Inhibition Effect of Several Inhibitors on 16MnR Steel in Bentonite

在放射性废物地质处置中,膨润土是首选的回填材料。膨润土膨胀、收缩过程中产生的应力会破坏废物容器的防腐蚀涂层;考虑到回填材料和地下水中含有的氯离子,可侵入到钢与膨润土界面,使钢去钝化而发生局部腐蚀。在结合工程实际的基础上,取现场地下水和柯尔碱膨润土对16MnR钢试片进行挂片腐蚀试验,分别添加六种常用的缓蚀剂,通过扫描电镜分析挂片表面腐蚀形貌,并用静态失重法计算腐蚀速率和缓蚀效率。试验结果显示,在0.5%的质量比添加条件下,缓蚀性能由高到低依次为亚硝酸钠、重铬酸钾、硅酸钠、钨酸钠、磷酸钠和钼酸钠,说明采用添加缓蚀剂改善16MnR钢废物容器腐蚀环境的方法是可行的。

Bentonite is a preferred backfill material in disposal of high level waste（HLW）.The stress producted in expansion and contraction process of bentonite will destroy the anticorrosion coating of waste container.Meanwhile,Cl-contained in the backfill material and groundwater can invade the steel/bentonite interface,resulting in depassivation and localized corrosion of steel.Corrosion coupon testing based on engineering practice was performed.16MnR steel specimens were immersed into the mixture of field groundwater and cole alkali bentonite,in which six commonly used inhibitors were added.After testing,SEM was used to analyze the surface corrosion morphology,and the corrosion rate and inhibition efficiency were calculated with static weight loss test.The results show that,the descending order of inhibition effect in 0.5% mass concentration was as follows： NaNO2,K2Cr2O7,K2CrO4,Na4SiO4,Na2WO4,Na3PO4,MoNa2O4.It is concluded that adding inhibitors to improve the corrosive environment of 16MnR steel waste containers is feasible.