Inhibition Effect of Several Inhibitors on 16MnR Steel in Bentonite

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.