Microstructural Effect of Diamond-Like Carbon Thin Film on Micro-Tribological Properties

摘要

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/cm~3 were deposited 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 spectros- copy. Increasing the bias voltage and the discharge current shifted the peak of the G-band shift toward high frequency and enlarged I(D)/I(G) ratio. Pin-on-Plate 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 1540 cm~(-1), but those did not vary with increasing I(D)/I(G). The friction coefficients were directly proportional to density of the film. Molecular orbital calculations revealed that the adhesion energy on the sp~3 bonding atom cluster was higher than that on the sp~2 bonding atom cluster.