Effects of proteins in corrosion of stainless steels used in traumatology

The corrosion behavior of stainless steels, AISI 304, AISI 316 and a steel that matches the requirements of the ASTM Standard F-138 of possible use in traumatology, was studied in the presence of proteins similar to those contained in the human skeletal muscle. The investigation was carried out using potentiodynamics polarization measurements and cyclic voltammetry, using an electrolyte similar to cellular fluid, which contains the same composition as the skeletal muscle, in proteins and salts. To evaluate the effect of the proteins, the tests were performed without and with the addition of proteins to the cellular fluid at 37 ° C. The electrochemical tests revealed that the proteins have a negative effect on pitting corrosion, according to the quality of the steel used to carry out the test, the most resistant being the AISI 316L and the F-138. Scanning electron microscopy (SEM), carried out after the cyclic voltammetry in cellular fluid in the presence of proteins, revealed the presence of a mixed layer, which is formed by oxides and proteins stuck to the surface of the metal. This layer looks to be a more unstable passive layer than the corresponding one without proteins. The Tafel plot revealed that the corrosion mechanism was a diffusional process controlled by proteins. The results were similar to those obtained in marine environments.