Tribological behavior of diamond-like carbon coatings with patterned structure deposited by the filtered cathodic vacuum arc

Patterned diamond-like carbon (DLC) coatings were deposited on a Si (100) substrate using the filtered cathodic vacuum arc technique. The effects of the patterning and of the coating thickness on tribological behavior of DLC coating were investigated using a ball-on-disk tribometer under dry and oil-lubrication conditions. The results suggest that 1 mm2 patterned structures delimited by 100-μm grooves can enhance the tribological properties. The coefficients of friction of the tested patterned films were 0.123 and 0.067 under dry and oil lubrication conditions, respectively, 10% and 21% lower than the coefficients of friction of the continuous DLC films with the same thickness. Raman spectroscopy measurements showed graphitized wear particles for both the continuous and patterned DLC films, but the debris of patterned DLC films having a greater degree of graphitization under dry sliding. The grooves of the patterned coatings could serve as a lubricant reservoir and trap the wear debris, which was beneficial for the tribological properties. The effect of the thickness of the patterned DLC films on their tribology behavior was also investigated. The 0.4-μm-thick patterned samples exhibited the lowest coefficients of friction of 0.105 and 0.058 under dry and oil lubrication conditions, respectively, while the 0.8-μm-thick patterned samples showed the lowest specific wear rate. In addition, the coefficients of friction of the patterned samples increased with an increase in the film thickness under oil lubrication conditions.