A Study On The Dechlorination Of Iron Artifacts And The Investigation Of New Inhibiting Decholrination Solutions

The changing rule of chemical and electrochemical states inside occluded cell (OC) on the localized corrosion for cast iron in alkaline solution during the electrochemical and immersion desalination process has been investigated in this paper, as well as the influence of the current and potential value on the desalination result of cast iron in the frequently-used calkaline solutions. In addition, a new inhibiting dechlorination solution has been developed for the archeological iron, which provided experiment data for the application of dechlorination technique on the archeological iron.A simulated occluded cell were used to study the effect of dechlorination on chemical and electrochemical states inside occluded cell (OC) on the localized corrosion for cast iron in alkaline solution. It has been found that the OC passed the anodic polarization (1mA/cm~2) in 3.5% NaCl solution for 48 hours can simulate the state of hole and crack of localized corrosion for cast iron in seawater. The dechlorination results increased with the increasing of the treatment time, the increasing of the current density and the negative movement of potential value as well, when such OC was passed through the galavanstatic and potentiastatic cathodic polarization or immersed in alkaline solution of 2.5% NaOH.The optimul values of the currents and potentials were obtained forsimulated cast iron dechlorided by different currents and potentials in the traditional alkaline solutions. The ingredients of the rust before and after treatments were analyzed by using the X-Ray Diffraction (XRD), X-Ray Photoelectron Spectra (XPS), and the surface morphology of the corrosion products before and after treatments were also studied by a Scanning Electron Microscope (SEM). The changing on the phase, ingredients and the morphology of the corrosion products were discussed during electrochemistry dechlorination treatment processes. The results showed that the extraction ratio of chloride ion increased with increasing of the current density. The optimum current density(0.5^0.75mA/cm ) was determined in our experiment. In addition, the extraction ratio of chloride ions also increased with the increasing of potential values, the potential values between -1.15—-1.175 was determined. The phase transformation occurred on the corrosion products during the dechloriation process—fromthe y -FeOOH phase into the Fe3C>4 phase which is more compact.Dechlorination effects of chemical and electrochemical techniqueson cast iron in ethylenediamine-containing akaline solutions and abluent-containing akaline solutions have been studied in this paper. Surface composition of the treated rust sample has been analyzed by infrared (IR) spectrum and ultraviolet (UV) spectrum. The dechlorination mechanisms is discussed in detail. In addition, the electrochemical behavior of the cast iron after dechlorination has been examined by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results showed that the dechlorination effects of chemical and electrochemical techniques on cast iron in this alkaline solutions are more effective than the traditional methods. The efficiency of the electrochemical dechlorination techniques is about one times higher than the traditional ways, meantime the anti-corrosion performance of the...