Electrochemical performance of TiCN coatings with low carbon concentration in simulated body fluid

TiCN coatings with low carbon concentrations (0.99 at.%-2.46 at.%) were deposited on Si(100) wafers via co-sputtering titanium and graphite targets by using unbalanced magnetron sputtering. The influence of carbon content on the microstructure and electrochemical properties of TiCN coatings in simulated body fluid was analyzed. The results revealed that the amorphous carbon (a-C) was absent from TiCN coatings (0.99 at.% or 2.05 at.% carbon), which exhibited favorable corrosion resistances in SBF. But the presence of a-C in TiCN coating (2.46 at.% carbon) lowered its hardness, and subsequently deteriorated its corrosion resistance in SBF. In particular, the TiCN coating with 2.05 at.% carbon presented the higher charge transfer resistance (Rct) as compared with the TiCN coating (0.99 at.% carbon) owing to more a-CNx and higher electrical resistivity.