Influence of iron microstructure on corrosion inhibitor performance in acidic media
Journal of Physical Chemistry C
State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016, China; Shenyang National Laboratory for Materials Sciences, Institute of Metal Research, International Centre for
Electrochemical measurements employing ac and dc techniques as well as atomic force microscopy were used to study the electrochemical corrosion behavior of ingot iron with two different microstructures: conventional polycrystalline ingot iron (CPU) and bulk nanocrystalline ingot iron (BNII) fabricated from CPU by severe rolling, without and with inhibitors. The corrosive media was 0.1 M H2SO4 solution, while thiourea (TU) was employed as inhibitor, with a concentration of 5.0 mM, as well as a 1:1 combination of TU and KI. Impedance and polarization results show that BNII was more susceptible to corrosion in the uninhibited acid. The presence of TU improved the corrosion resistance of both specimens comparably, while KI reduced the inhibition efficiency of TU. Infrared spectrophotometry revealed that the interfacial species for CPU and BNII in the presence of TU were quite identical and markedly different from that in TU + KI. Molecular dynamics (MD) simulations were performed to illustrate the adsorption process of TU at a molecular level, and the theoretical predictions showed good agreement with the electrochemical results. © 2009 American Chemical Society.
Acidic media; Adsorption process; Bulk nanocrystalline ingot irons; Concentration of; Corrosive media; Electrochemical corrosion behavior; Electrochemical measurements; Infrared spectrophotometry; Inhibition efficiency; Inhibitor performance; Molecular dynamics simulations; Molecular levels; Polycrystalline ingots; Theoretical prediction; Adsorption; Atomic force microscopy; Corrosion resistance; Dynamics; Electrochemical corrosion; Ingots; Microstructure; Molecular dynamics; Thioureas; Urea; Corrosion inhibitors