The corrosion inhibition effect of phytic acid on 20SiMn steel in saturated Ca(OH) 2 solution with 1 mol L −1 NaCl

A wise strategy to hinder the degradation of the steel rebar in concrete is finding a corrosion inhibitor to resist pitting corrosion at passive state as well as the general dissolution at active dissolution state. In this paper, the corrosion inhibition effect of phytic acid (IP6) on 20SiMn steel was investigated in the simulated concrete solution with chlorides, Sat.Ca(OH)2+1 mol/L NaCl(pH=12.9), by electrochemical methods and surface analysis techniques. The results show that IP6 could prolong the incubation time of 20SiMn steel from passive to pitting corrosion and enhance the charge-transfer resistance to a certain extent with the inhibition efficiency of around 30~50%. This is ascribed to the preferential adsorption of IP6 over chloride ion on the passive film through PO4 functional groups, which lead to the formation of a compact chelation film.