Esra Kus

A Comparison of the Corrosion Behavior of Nanocrystalline and Conventional Al 5083 Samples

Abstract Pitting scan (PS) and electrochemical impedance spectroscopy (EIS) techniques were used to evaluate the corrosion behavior of nanocrystalline (NC) samples and conventional Al 5083 (UNS A95083) in three solutions with different chloride concentrations. The PS obtained in 0.5 N sodium chloride (NaCl) and in 0.5 M sodium sulfate (Na2SO4) + 0.1 N NaCl indicated that pitting should occur in these solutions. These results were confirmed by EIS data that were recorded for up to 25 days. For exposure to 0.5 M Na2SO4 + 0.05 N NaCl the pitting (Epit) and protection (Eprot) potentials determined after exposure for 2 h suggested that pitting would not occur in this solution. However, the initial impedance spectra were indicative of pitting. Tests carried out after exposure for 2 days and 3 days showed passive behavior, but starting with exposure for 5 days, pitting was again indicated for all three samples. PS performed at the end of the EIS tests suggested that this result was due to the increase in corrosi...

Evaluation of Nontoxic Polymer Coatings with Potential Biofoul Release Properties Using EIS

The corrosion resistance of steel panels coated with pentasiloxanes has been evaluated by electrochemical impedance spectroscopy (EIS) during exposure to 0.5 N NaCl. Two fluorinated and a nonfluorinated pentasiloxane havebeen prepared to develop nontoxic polymer coatings with improved biofoul release properties. Depending on the terminal epoxy group type, two different crosslinking/cure chemistries were utilized. The first type of cross-linking reaction involved room-temperature UV cure with a photoacid catalyst and the second cross-linking reaction was phenol-catalyzed thermal cross-linking with a, ω-diaminoalkanes [NH 2 -(CH 2 ) n -NH 2 ]. The EIS data suggest that the nonfluorinated pentasiloxane provided better corrosion protection than the two fluorinated pentasiloxanes and that room-temperature UV cure with a photoacid catalyst provides better corrosion protection than phenol-catalyzed thermal cross-linking.