Restructured graphene sheets embedded carbon film by oxygen plasma etching and its tribological properties

Abstract

An oxygen plasma etching technique was introduced for improving the tribological properties of the graphene sheets embedded carbon (GSEC) film in electron cyclotron resonance plasma processing system. The nanostructural changing in the film caused by oxygen plasma etching was examined by transmission electron microscope, Raman spectroscopy and X-ray photoelectron spectroscopy, showing that the 3nm thick top surface layer was restructured with smaller graphene nanocrystallite size as well as higher sp3 bond fraction. The surface roughness, mechanical behavior and tribological properties of the original GSEC and oxygen plasma treated GSEC films were compared. The results indicated that after the oxygen plasma treatment, the average roughness decreased from 20.8±1.1nm to 1.9±0.1nm, the hardness increased from 2.3±0.1GPa to 2.9±0.1GPa, the nanoscratch depth decreased from 64.5±5.4nm to 9.9±0.9nm, and the wear life increased from 930±390 cycles to more than 15,000 frictional cycles. The origin of the improved tribological behavior was ascribed to the 3nm thick graphene nanocrystallite film. This finding can be expected for wide applications in nanoscale surface engineering.