Electrochemical anticorrosion behaviors of the electroless deposited Ni-P and Ni-P-PTFE coatings in sterilized and unsterilized seawater

The Ni-P and Ni-P-PTFE coatings were deposited on mild carbon steel surface via electroless deposition process. The as-deposited coatings were characterized through XRD, SEM, and EDS. The electrochemical anticorrosion behaviors of the coatings in natural seawater were investigated by measurements of potentiodynamic polarization curves, open circuit potential, and electrochemical impedance spectra. The results showed that by immersion in natural seawater for 3-7 days the Ni-P and Ni-P-PTFE coatings could provide maximum protection for the substrate. With regard to the PTFE incorporation, the coating with large amount of PTFE possessed a porous microstructure and hence poor electrochemical anticorrosion performance. Concerning the effect of the ocean microorganisms noticeable variations on electrochemical parameters have been observed though reliable consequence was yet to draw via cultivation and breeding of the ocean microorganisms in subsequent work. (C) 2010 Elsevier B.V. All rights reserved.