Deposition of TiN films on Co–Cr for improving mechanical properties and biocompatibility using reactive DC sputtering

This study reports the deposition of TiN films on Co–Cr substrates to improve the substrates’ mechanical properties and biological properties. In particular, the argon to nitrogen (Ar:N 2 ) gas flow ratio was adjusted to control the microstructure of the TiN films. A Ti interlayer was also used to enhance the adhesion strength between the Co–Cr substrate and TiN films. A series of TiN films, which are denoted as TiN-(Ar/N 2 )1:1, Ti/TiN-(Ar/N 2 )1:1, and Ti/TiN-(Ar:N 2 )1:3, were deposited by reactive DC sputtering. All the deposited TiN films showed a dense, columnar structure with a preferential orientation of the (200) plane. These TiN films increased the mechanical properties of Co–Cr, such as the critical load during scratch testing, hardness, elastic modulus and plastic resistance. In addition, the biological properties of the Co–Cr substrates, i.e. initial attachment, proliferation, and cellular differentiation of the MC3T3-E1 cells, were improved considerably by deposition of the TiN films. These results suggest that TiN films would effectively enhance both the mechanical properties and biocompatibility of biomedical Co–Cr alloys.