Electrochemical behaviour of advanced stainless steel implant material in saline physiological solution with calcium and phosphate ions and serum protein

The effect of serum protein, calcium and phosphate ions on the corrosion re sistance behaviour of advanced stainless steel, such as nitrogen bearing ty pe 316L SS was studied by potentiodynamic polarization experiments. The cri tical parameters associated with passive film breakdown and repassivation w ere determined. The pitting and the pit- protection potentials of nitrogen bearing stainless steel showed a noble shift compared to the commonly used 316L stainless steel implant material. An investigation was carried out to study the extent of metal ions leached out from the implant material by conducting accelerated leaching studies. T he metal ions of interest namely, iron. chromium and nickel were determined . The leaching of metal ions was significantly reduced in the case of nitro gen bearing stainless steel, which can be attributed to the enrichment of n itrogen at the passive film that could have impeded the release of metal io ns through the passive film. inhibitory effect was observed with calcium an d phosphate ions. The presence of serum enhanced the rate of corrosion and plays a major role in surface degradation of implant material.