In vitro vs in vivo corrosion analyses of two alloys

The in vitro and in vivo corrosion characteristics of two alloys, cast Co-Cr-Mo (ASTM F75) and wrought Ni-Cr-Mo, were evaluated using electro-chemical corrosion analysis. Two in vitro electrolytic solutions were utilized, an isotonic saline solution consisting of 0.9 w/o NaCl in distilled water and an isotonic saline solution with 10 v/o sterile calf serum. The in vivo environment was created by implanting cylindrically shaped specimens of each alloy into the back muscles of New Zealand white rabbits. Cyclic anodic and cathodic polarization curves were generated for the three test conditions and subsequently were compared. Anodic curves conducted using the isotonic saline and isotonic saline plus serum electrolyte solutions were very similar to the anodic curves generated for the implanted alloy specimens for both alloys. The corrosion rates predicted from the in vitro and in vivo cathodic polarization curves were not statistically different for the three test conditions. Overall, the corrosion data generated using the in vitro environmental conditions adequately predicted the in vivo corrosion behavior of the cast Co-Cr-Mo and wrought Ni-Cr-Mo alloys.