Electrochemical behavior of diamond-like carbon films for biomedical applications

Diamond-like carbon (DLC) films have several advantages in biomedical applications such as high hardness, chemical inertness, low friction and electrical insulation. Furthermore, DLC-coated STS 316L films have been reported to have a good biocompatibility. In addition, corrosion resistance is the first consideration for the biomaterials to be used in the body. DLC films have been deposited onto substrates of STS 316L using rf plasma-assisted chemical vapor deposition (PACVD) with benzene (C6H6) or a mixture of C6H6 and silane (SiH4) as process gas. Three kinds of DLC films were prepared as a function of bias voltage and Si incorporation. Corrosion behavior of DLC films was investigated by electrochemical techniques (potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS)) and surface analytical techniques (atomic force microscopy (AFM) and scanning electron microscopy (SEM)). The electrolyte used in this test was a 0.89% NaCl of pH 7.4 at temperature of 37 °C. Electrochemical measurements showed that DLC films with higher bias voltage and Si incorporation could improve corrosion resistance in the simulated body fluid environment.