Investigation of Nitinol Resistance to Fretting and Crevice Corrosion
The results have shown that Nitinol rods locked in titanium pedicle screws demonstrate inferior resistance to fretting and crevice corrosion compared with traditional Ti6Al4V or CoCr rods. Untypical corrosion damage including erosions combined with the build-up of titanium oxide as a corrosion product on surface of Nitinol rods in areas where it was in contact with titanium pedicle screw was observed after fretting and immersion tests. This damage was similar to that found previously on few explanted rods. It was revealed that the pedicle screw design affects the amount of corrosion damage observed after the tests dramatically. It was also found that the creation of defectless oxide layer on the surface of Ti6Al4V screws by low voltage microacr oxidation may prevent the development of corrosion damage on Nitinol rods.