Characterization and degradation comparison of DLC film on different magnesium alloys

Recently, magnesium (Mg) alloys have been attracted as biodegradable implants. However, high degradation rate in human body limits its application. Modifying material surfaces with a coating layer is an effective means to control degradation, and biocompatibility. In this study, thin diamond-like carbon (DLC) films were synthesized on different magnesium alloy substrates by radio frequency plasma assisted chemical vapor deposition (RFPACVD). The morphology, composition and structure of the coating layers were investigated with scanning electron microscopy (SEM) with an energy dispersive spectroscopy (EDS), micro-raman spectra (RAMAN), and Atomic force microscopy (AFM). Static contact angle measurement and nanoindentation test were also used to analyze surface properties. The degradation behavior of naked and coated Mg alloy were evaluated in stimulated body fluid (SBF), and DLC layers on different Mg alloy substrates significantly decreased the degradation rate of substrate, which is useful for the biological applications especially in bone tissue and cardiovascular stent.