Tribological behaviors of oxygen-doped carbon coatings deposited by ion-irradiation-assisted growth

Abstract

Oxygen-doped carbon coatings were deposited by ion-irradiation-assisted growth using an electron cyclotron resonance plasma processing system, and the effects of the O 2 content on the coating's structure and tribological behavior were studied. During the coating deposition, O + , O 2 + , and Ar + ions in the oxygen plasma were attracted to irradiate the growing coating surface , realizing oxygen plasma during-etching. X-ray photoelectron spectroscopy characterization showed that the O 2 addition incorporated some oxygen atoms into the carbon coating, and the sp 3 / sp 2 ratio of the entire coating increased. Such structural changes made the carbon coating present higher nanoscratch resistance and longer wear life that increased from 990 cycles to more than 5000 cycles. Finally, the reason why the oxygen doping can induce the sp 3 / sp 2 ratio to increase was suggested to be ion-irradiation-induced chemical recombination energy release, which could only occur when the O 2 introduction reduced the atom displacement threshold energy. • Oxygen-doped carbon coatings were deposited by ion-irradiation-assisted growth. • Plasma during-etching was realized by attracting O + , O 2 + , and Ar + ions to irradiate the growing coating. • After doping, the wear life increased due to the increase in sp 3 / sp 2 of the entire coating. • The increase in sp 3 / sp 2 was caused by ion-irradiation-induced chemical recombination energy release.