Titanium and
cobalt alloys, as well as some
stainless steels, are among the most frequently used materials in orthopaedic surgery. In industrialized countries,
stainless steel devices are used only for temporary implants due to their lower corrosion resistance in physiologic media when compared to other
alloys. However, due to economical reasons, the use of
stainless steel alloys for permanent implants is very common in developing countries. The implantation of
foreign bodies is sometimes necessary in the modern medical practice. However, the complex interactions between the host and the can implant weaken the local immune system, increasing the risk of
infections. Therefore, it is necessary to further study these materials as well as the characteristics of the superficial film formed in physiologic media in
infection conditions in order to control their potential toxicity due to the release of metallic
ions in the human body. This work presents a study of the superficial composition and the corrosion resistance of AISI 316L
stainless steel and the influence of its main alloying elements when they are exposed to an acidic
solution that simulates the change of pH that occurs when an
infection develops. Aerated simulated body fluid (SBF) was employed as working
solution at 37 degrees C. The pH was adjusted to 7.25 and 4 in order to reproduce normal body and disease state respectively. Corrosion resistance was measured by means of electrochemical impedance spectroscopy (EIS) and anodic polarization curves.