Deposition of diamond-like carbon films using hollow cathode plasma source

Diamond-like carbon (DLC) films are deposited on AISI 304 stainless steel substrates using hollow cathode chemical vapor deposition (CVD). The substrate bias voltage is varied from 0 to -200 V to investigate its effect on the structural and mechanical properties of the films. Raman spectra show the formation of the G (graphite) peak and D (disorder) peak in the films. X-ray photoelectron spectroscopy (XPS) data also confirm the existence of C=C (sp²) and C-C (sp³) bonds. Our experiments show that the sample bias has a critical influence on the thickness and hardness of the deposited films. The largest thickness (1700 nm) and the highest hardness (HV1099) are achieved at a bias voltage of -50 V. All the films show low friction coefficients and the sample treated at -200 V exhibits the lowest friction coefficient. The enhancement mechanism is also described.