Structure, mechanical and tribological behaviors of Ti/GLC multilayer films deposited by DC magnetron sputtering

The Ti/GLC multilayer films (MFs) with GLC monolayer thickness (M-GLC) of 1.2-26.8 nm were deposited on Si and alloy substrates by magnetron sputtering. Microstructure features of the Ti/GLC MFs were investigated by the Transmission Electron Microscopy (TEM), the X-ray Diffraction (XRD), and the Raman spectrum. Results indicated that the M-GLC could tailor the microstructure of the GLC-MFs. Simultaneously, the Ti/GLC-MFs exhibited interface reaction due to the mutually growth-promoting effect at small M-GLC, and the fringes of the high resolution TEM image proved the formation of TiC nanocrystalline at the layer interface of Ti/GLC. Based on the content of the sp(2)-C dramatically increased, the Ti/GLC-MFs with M-GLC of 1.2 nm were considered to transform into nanocomposite structure films. And then, Nano-Indentation Testing showed that the hardness of GLC-MFs varied from 12.5 to 24.7 GPa, with the highest hardness obtained at an M-GLC of 1.2 nm. Finally, the tribological properties of the Ti/GLC-MFs were investigated using a Ball-On-Disk Tribometer under humid air. And the test result was found that the MFs with an M-GLC of 1.2 nm also exhibited the lowest friction coefficient of 0.06 and the highest wear resistance.