Novel Perimidine Derivatives as Corrosion Inhibitors of HRB400 Steel in Simulated Concrete Pore Solution

1H-Perimidine (PMD) and 1H-perimidine-2-thiol (SPMD) were developed as inhibitors for reinforcing steel in a simulated concrete pore (SCP) solution. Electrochemical measurements, contact angle experiments, scanning electron microscopy (SEM) and quantum chemical calculations were used to investigate the corrosion performance and adsorption mechanisms. The experimental results showed that owing to the structure of SPMD containing a 2-position sulfhydryl group, SPMD is superior to PMD as a corrosion inhibitor for HRB400 reinforced steel in the SCP solution, and its corrosion efficiency can reach more than 80%. Moreover, the introduction of nitrogen and sulfur atoms into the inhibitor not only can coordinate with Fe atoms to form strong bonds but also is useful for preventing charge transfer in the metal corrosion process. More importantly, the perimidine derivatives can spontaneously adsorb on iron, and the adsorption process obeys the Langmuir isotherm. The research results show that the perimidine derivatives can improve the durability of concrete structures.