Thin film of zirconia (ZrO 2 ) was prepared onto mechanically polished and electrochemically prepared surfaces of 316L stainless steel by direct and pulse current. Electrodeposition process was performed at ambient temperature. Current density used was 1.7 mA.cm -2 . After that, the electrodeposits were annealed at 400 °C for 2h. X-ray diffraction patterns obtained indicated that the ZrO 2 coatings were nanocrystaline with a tetragonal crystallographic structure. Grain size of the coatings determined by Sherier equation were 19 and 9 nanometer for direct and pulse current, respectively. Scanning electron microscopy investigation showed that the surface preparation have no significant effect on the morphology of coatings. However, the nature of current (i.e. Ac or Dc) has a significant effect on electrodeposition process. The coatings produced by direct current showed a heterogeneous structure having a “crack mud” appearance. Conversely, pulse current produced a more uniform and dense coating with a smaller grain size. EDS results indicated that in all conditions, ZrO 2 coatings cover the entire surface. Cross sections of the coatings deposited by pulse current showed a uniform mean thickness of 1.5 µm on all specimens. In order to evaluate the corrosion performance of coatings, Tafel and cyclic polarization tests were performed in 3.5% NaCl solution. Results obtained revealed that surface preparation has a significant effect on corrosion behavior. Coatings produced by pulse current had higher corrosion resistance acting as a barrier coating due to its uniform and dense morphology. Pulse coatings provided a passive behavior observed on the Tafel polarization plots. The ZrO 2 coatings produced on electrochemically prepared surfaces showed a very small passive region on the anodic Tafel polarization curves. This is believed to be due to the effect of surface preparation. EIS data obtained from ZrO 2 coatings showed that pulse coatings can behave as a physical barrier for corrosion. It was observed that the pulse coatings produced on mechanical polished substrate could prevent the pitting corrosion. Pulse coatings have a good adhesion to substrate. Key Word Zirconia; nanostructure; electrodeposition; stainless steel; corrosion resistance
