Evaluation of the corrosion resistance of ear piercing studs in a culture medium by electrochemical impedance spectroscopy

Abstract

In this investigation, electrochemical impedance spectroscopy (EIS) was used to compare the corrosion resistance presented by two gold-coated commercial studs used for ear piercing, and produced using nickel containing substrate alloys, with that exhibited by a laboratory-made titanium stud in a cell culture medium. The aim was to evaluate Ti as a potential material for the manufacture of ear piercing studs. Scanning electron microscopy examination of the coating defects on the two commercial studs, both before and after their exposure to the culture medium, have shown the establishment of a corrosion process. Instrumental neutron activation analysis results of the culture medium after 10 days of contact with the commercial studs have shown the presence of nickel among the alloying elements leached out from the surfaces of the studs in spite of the high corrosion resistance exhibited by one of them. EIS has been demonstrated to be a sensitive technique, not only to rank the corrosion resistance of the studs, but also to detect some features of the corrosion process, like pore blocking and oxide layer structure. From the results it was concluded that Ti is a candidate material for ear piercing studs due not only to its high corrosion resistance, but also to its non-cytotoxicity and the absence of nickel in the stud composition.