Surface modification of NiTi alloys using nitrogen doped diamond-like carbon coating fabricated by plasma immersion ion implantation and deposition

Nitrogen doped diamond-like carbon (N-DLC) coating was prepared on NiTi alloys using plasma immersion ion implantation and deposition (PIIID). The Raman spectrum confirms the coating processes the structure of diamond-like carbon. The XPS results reveal the nitrogen is doped into the diamond-like carbon, and CAN bonds are formed in the coating. The scratch test displays that the DLC coating has good adhesion strength with the substrate. Anodic polarization has been carried out to examine the electrochemical corrosion behavior of the coated and uncoated samples. The result indicates that the corrosion resistance of the NiTi alloys is improved by the coating.