IN-VITRO ELECTROCHEMICAL INVESTIGATIONS OF ADVANCED STAINLESS-STEELS FOR APPLICATIONS AS ORTHOPEDIC IMPLANTS

Potentiodynamic anodic polarization experiments on advanced stainless steels (SS), such as nitrogen-bearing type 316L and 317L SS, were carr ied out in Hank's solution (8 g NaCl, 0.14 g CaCl2, 0.4 g KCl, 0.35 g NaHCO3, 1 g glucose, 0.1 g NaH2PO4, 0.1 g MgCl2, 0.06 g Na2HPO4 . 2H(2 )O, 0.06 g MgSO4, 7H(2)O/1000 mt) in order to assess the pitting and c revice corrosion resistance, The results showed a significant improvem ent in the pitting and crevice corrosion resistance than the commonly used type 316L stainless steel implant material, The corrosion resista nce was higher in austenitic stainless steels containing higher amount s of nitrogen, The pit-protection potential for nitrogen-bearing stain less steels was more noble than the corrosion potential indicating the higher repassivation tendency of actively growing pits in these alloy s, The accelerated leaching study conducted for the above alloys showe d very little tendency for leaching of metal ions, such as iron, chrom ium, and nickel, at different impressed potentials, This may be due to the enrichment of nitrogen and molybdenum at the passive film and met al interface, which could have impeded the releasing of metal ions thr ough passive film.