Microstructural effect of diamond-like carbon thin film on micro-tribological properties

Abstract

This paper describes the microstructural effect of Diamond-Like Carbon (DLC) thin film on micro-tribological properties. DLC thin films with density of 1.9-2.4 g/cm3ted on Silicon (111) surface by Plasma-Enhanced CVD method of the hot cathode PIG discharge type. The effect of deposition conditions on the microstructure of DLC thin film was evaluated by Raman spectroscopy. Increasing the bias voltage and the discharge current shifted the peak of the G-band shift toward high frequency and enlarged iD)i(g)ratio. Pin-on-PIate friction experiments were carried out using a diamond pin in high vacuum. The friction coefficients of DLC thin films indicated constant values during the friction. The friction coefficients increased with shifting G-band toward low frequency in the range above 1 540 cm1 but those did not vary with increasing i)i(g) The friction coefficients were directly proportional to density of the film. Molecular orbital calculations revealed that the adhesion energy on the sp3 bonding atom cluster was higher than that on the sp2 bonding atom cluster.