查看文章

This paper objective was to evaluate the degradation characteristics of polytetrafluoroethylene (PTFE) coatings on stainless steel orthodontic wires with memory shape while immersed in tuna fish derived products. EIS was the major investigative technique, since it has the potential to discover new information on the processes occurring, while not interfering significantly with the mechanism operating. The spectra of uncoated and coated orthodontics stainless steel wires were recorded, and the data were analyzed in order to evaluate the equivalent circuit (EC) parameters and subsequently the degradation characteristics of each material. The corresponding corrosion morphologies after polarization test was also observed using scanning electron microscopy (SEM). Comparison of the electrochemical behaviour, in the condition of exposure to aggressive media, for stainless steel orthodontic wires with memory shape, coated with a PTFE porous layer versus the uncoated alloy sample was done. The coatings stainless steel orthodontic wires samples exhibited more positive zero current potential, higher breakdown potential, and lower anodic current densities than the uncoated ones. Impedance spectra were interpreted in terms of a duplex film, with corrosion resistance arising mainly due to the thin inner layer as the outer layer being more porous was less sealed. Pseudo-capacitive behaviour and high corrosion resistance were registered for the coated stainless steel alloy, in the medium to low frequency ranges. This paper results are valuable for estimation of coated and uncoated stainless steel orthodontic wires corrosion resistance and for …