Improvement of thermal stability, adhesion strength and corrosion performance of diamond-like carbon films with titanium doping

Ti-doped diamond-like carbon (Ti-doped DLC) films were deposited on 304 stainless steel through a pulsed filtered cathodic vacuum arc deposition with an individual cathodic arc source. Structural dependent thermal stability, mechanical properties, adhesion, and corrosion performance were thoroughly investigated as a function of the Ti content. Only 0.8 at.% Ti content in the DLC films offers the relatively high hardness (28.8 GPa), high corrosion resistance, enhanced adhesion strength as well as improved thermal stability compared to the undoped DLC films. The reduction in the internal stress and the sp(3) content associated with a slight decrease in the mechanical properties is from Ti doping. Higher thermal stability is due to the TiC phase in the Ti-doped DLC structure. Enhancement of the adhesion strength is owing to the relief of the internal stress and the occurrence of the strong atomic intermixing bond at a Ti-doped DLC/Ti intermediate layer interface. Interestingly, the formation of the TiO2 film on the Ti-doped DLC surface due to a small amount of Ti doping significantly exhibited a better corrosion performance. Ti-doped DLC films, therefore, are a promising coating for tribological applications.