十二烷基硫醇在Fe表面自组装成膜及对其的腐蚀保护

SAMS OF DODECYL MERCAPTAN AND ITS CORROSION PROTECTION ON IRON SURFACE

应用自组装技术在Fe电极表面制备正、叔十二烷基硫醇自组装膜,用反射傅立叶红外光谱(FT-IR)、电化学阻抗谱(EIS)和Tafel极化曲线对正、叔十二烷基硫醇自组装膜进行表征,结果表明,正、叔十二烷基硫醇都能在Fe表面形成自组装膜;设计了自组装膜的等效电路,并对EIS数据进行拟合;EIS拟合结果和Tafel极化曲线均表明,正、叔十二烷基硫醇自组装膜对Fe电极在0.5 mol/L NaCl溶液中均具有较好的缓蚀作用,并且前者的缓蚀作用强于后者。

Self-assembled monolayers（SAMs）of n-and t-dodecyl mercaptan were prepared on iron surface by self-assembly methods.From the results of FT-IR,it can be found that both the n-and t-dodecyl mercaptan can self-assemble on the surface of iron.Then the electrochemical impedance spectroscopy（EIS）and the Tafel polarization curves were performed to characterize the anticorrosion capability of the SAMs in 0.5 mol/L NaCl solution.The general equivalent circuits for the n-and i-dodecyl mercaptan SAMs were established.Based on the results of the EIS,proper equivalent circuit was chosen to fit the Nyquist impedance plots.The inhibition efficiency（IE）of the SAMs on iron corrosion have been calculated according to the fitted results and the Tafel polarization curves.When the iron electrode self-assembled in the n-and t-dodecyl mercaptan for 3h,the IE of the SAMs can reach about 89%and 80%respectively.Comparing with the SAMs of the t-dodecyl mercaptan, the SAMs of n-dodecyl mercaptan have more effective corrosion inhibition for iron as indicated by the high charge-transfer resistance shown in EIS and the positive corrosion potential in the Tafel polarization curves.It is quite possible that the steric hindrance of t-dodecyl mercaptan is bigger than that of n-dodecyl mercaptan. Therefore,it is easy to understand that the quality of the n-dodecyl mercaptan SAMs is better than that of the t-dodecyl mercaptan.