Tribological properties of plasma source ion implanted DLC film on 2024 aluminum alloy

Based on plasma source ion implantation with nitrogen, 2024 aluminum alloy (LY12) was further implanted with titanium plus nitrogen, or with titanium plus nitrogen and titanium, to generate the intermediate layers of different compositions and thickness, followed by implantation with carbon to generate DLC films on the intermediate layers. The composition depth distributions of the modified layers were characterized using X-ray photoelectron spectroscopy. The nano-hardness and the friction and wear behavior of the DLC films were examined, while the effect of the intermediate layer composition and structure on the tribological properties of the DLC films against steel was discussed. Results showed that the carbon-implanted layer was composed of DCL films whose properties were closely related to the composition and structure of the intermediate layers. The DLC films on various intermediate layers showed much higher nanohardness and better wear resistance than the ones without the intermediate layer. Moreover, the implanted carbon reacted chemically with the elements in the intermediate layer, which contributed to increasing the interfacial bonding strength between various gradient layers. Thus the DLC films with optimized tribological behavior could be prepared by properly screening the intermediate layer which affected the appearances, thickness and structures of the carbon-implanted modified layers. In this sense, the DLC film on the intermediate layer after the implantation with titanium, nitrogen and titanium showed the best wear resistance.